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pre reading -

1. 단어 학습(scanning 후)

2. schema activation 실시

reading -

1. jigsaw reading 활용 학습자 중심 읽기 수업 진행

2. comprehension check up 문제 풀기

3. 읽고 summary 적기

post-reading -

1. post reading 활동으로 이런 케이스 말고 도시에서 지구 온난화를 친환경적으로 예방하려 노력하는 경우 찾아보기

2. 도시에서 지구 온난화를 예방하려는 방법들에 대해

조원들과 공유해보고 발표해보기

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Article 5.

Speaking 활동: 채식 브이로그 ~~

학습 목표:관계대명사와 분사구문을 활용하여 채식을 요리하고 먹는 자신의 일상을 설명할 수 있다.

<개요>

대상: 고1

기간: 1주

결과물: 3분 분량의 영어 브이로그 영상

언어 요소: 관계 대명사, 분사구문 포함된 영어 스크립트 작성

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<내용적 단점과 보완>

1. 자기 성찰 및 심화 학습 기회 부족: 'Today's note about climate crisis' 활동이 단순한 지식 요약으로 남을 수도 있을 것 같음.

"기후 위기 해결을 위해 개인적으로 어떤 노력을 할 수 있을까?", "이 학습을 통해 나의 가치관에 어떤 변화가 생겼는가?" 등의 질문을 제시하고 실생활에서 실천할 수 있는 작은 행동으로 연계되도록 독려하면 좋을 것 같음.

2. 설득적 글쓰기의 근거: 기후 변화 해결책을 3가지 제시하고 설득적인 글을 작성하는데 "should/shouldn't" 표현을 활용하는 것에 초점을 맞춰져 있어 실제적이고 구체적인 해결 방안 제시가 어려워 보임.

학생들이 다양한 전문가 또는 기관에서 제시하는 기후 변화 해결책 사례를 조사하고 분석하는 시간을 가진 후 개인/사회적 측면에서 나눠서 제시하기

3. 영상의 난이도: What Causes Climate Change Animation을 보고 답해야 하는 문제들의 개수와 답의 난이도가 다소 부담이 있음.

퀴즈 형태를 간소화 하거나 영상을 보고 바로 문제 풀 수 있는 도구(?) 사용하기

<교육적 단점과 보완>

1. AI 활용과 관련된 사전 교육: Chat GPT를 활용하여 학생들의 인지적 부담을 줄일 수 있지만 AI가 제공하는 정보를 무차별적으로 수용할 수도 있음

AI가 생성하는 정보의 특성과 비판적으로 정보를 검증하는 방법에 대한 사전 교육을 제공

2. 평가 척도의 모호함: 자기평가나 동료평가의 척도가 구체적이지 않아서 유의미한 reflection이 어려워 보임.

건설적인 피드백이 가능하도록 내용, 언어 형식 측면에서 나눠서 제시하도록 안내하기

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Pre

도심 속 roof garden의 효과에 관한 뉴스 영상

While

글을 읽고 내용 요약, 효과 확인

우리 학교 지붕(또는 유휴공간) garden 디자인하기

Post

가장 좋은 아이디어에 투표

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pre-reading : 그리스, 옥상정원 등의 사례들의 공통점 살펴보고 이렇게 건물을 건축하는 이유에 대해 짝과논의해보기, vocabulary

post reading 후 project : 내가 리모델링/설계하고 싶은 건물 선정해서 어떻게 옥상을 디자인(color, design 등)할 것인지에 대해서 글쓰고 건물 3d프로그램 활용해서 디자인해보기(기술교과와 융합)

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1. 배경지식 쌓기

(1) 아마존 관련 영상 시청

(2) 어휘 학습

2. 읽기 활동

3. 아마존이 없어진다면? 브레인스토밍

4. 글감 찾아서 그룹끼리 글 작성

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Climate Action Plan 제안서 쓰기

1. 목표 : 기후위기에 대응하는 실질적인 방안 구상

2. 활동 방법: 폭염으로 인한 피해를 줄이기 위한 정책 또는 캠페인 아이디어를 영어로 작성

3. 형식 :

서론: 폭염의 위험 설명

본론: 해결 방안 2~3가지 제시

결론: 우리가 할 수 있는 일 요약

(영어 작문 과제 및 발표로 연계 가능)

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Amazon Forest Dieback

아마존과 관련된 간단한 영상 시청으로 동기 부여하기

내용과 관련된 어휘를 그림 또는 이미지로 학습하기

아마존 숲 가뭄으로 인해 일어나고 있는 현상 사례 조사하기

문제 해결을 위한 실천 방안 토의해서 포스터 만들기

모둠 발표 및 동료평가하기

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Pre reading 관련 영상 시청 및 기사 관련 단어 학습

Reading main idea 찾기

Postreading 인과 관계를 나타내는 어휘 표현 highlighting 기법 활용해서 요약문 만들기

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1. 기사 분석 및 토론 – Critical Reading

핵심 내용 정리: 학생들에게 기사를 읽고 주요 주장, 소송 경과, 판결 의미를 요약하도록 함

어휘 및 표현 학습: 법적 용어(standing, constitutional rights, injunctive relief, public trust doctrine 등)를 정리하고, 의미와 사용 예문 만들기.

깊이 있는 질문:

“청소년이 법원에 소송을 제기할 수 있는 자격은 왜 중요할까?”

“대법원이 이 사건을 거부한 결정이 가지는 의의는?”

"개발과 환경보호, 무엇을 우선해야할까?"

2. 역할극 (Role-play Debate)

배역 설정: 학생들을 ‘원고 측 청소년들’, ‘정부 측 변호사’, ‘판사’, ‘환경운동가’로 나누어 역할극.

주제:

원고 측은 “정부가 화석연료 정책을 통해 우리 권리를 침해하고 있다”고 주장.

정부 측은 “환경보호를 명목으로 개발을 멈출 수 없다”라고 반박.

토론 진행:

Opening statements

교차 질문 및 rebuttal

판사 혹은 전체 학생들이 최종 판결—토론 후에는 실제 판결과 비교해보는 시간을 가지면 효과적입니다.

3. 작문 과제 – Opinion Essay

주제 예시: “Should youth have the legal right to sue their government over climate change?”

논리 전개: 찬성/반대 입장 정리, 기사 근거 활용, 개인 의견 포함.

표현 연습: “In my view…”, “However…”, “Therefore…” 같은 논리적 문장 구조 사용.

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조원: 김도윤, 양은정, 최새봄

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조원: 김도윤, 양은정, 최새봄

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article 8번 활용

post-reading: writing 수업

본문 읽은 후, 환경에 긍정적인 활동이라고 생각햇으나, 실제로는 효과적이지 않거나 오히려 climate crisis를 악화하는 사례 조사하고 글쓰기 (+ 발표하기?)

사례 조사 주제 예시

바이오연료: 식량 작물을 연료로 사용하여 식량 부족과 삼림 벌채 야기

전기차 배터리: 리튬 채굴로 인한 환경 파괴

재활용 플라스틱: 실제 재활용률이 낮고 마이크로플라스틱 문제 발생

풍력발전: 조류 사망과 소음 공해 문제

일회용 대신 면 가방: 면 재배의 물 사용량과 화학 농약 문제

3단계: 글쓰기 구조

Introduction: 환경에 좋다고 생각했던 이유

Body: 실제 부작용이나 비효율성 근거

Conclusion: 진정한 환경 보호를 위한 대안 제시

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내용: Pre-reading의 2번 활동에서, 단순히 동물 이름을 나열하는 것이 아니라 멸종 위기의 동물을 적게 하면 내용 연관이 높아질 것 같다.

교육: 스피치 압축을 학생들이 어려워할 것 같아서, 이에 관한 가이드라인이나 지도가 좀 있었으면 좋겠다. 왜 압축 활동이 있는지 목적도 알려주면 좋겠다.

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기사 주제- 기후변화로 인해 목숨을 잃는 사람이 늘어가고 있다!

활동 1: 기후변화가 우리나라에 미치고 있는 영향을 조사해서, 현재완료 have pp를 사용하여 글쓰기.

활동 2: 이러한 문제에 대응하기 위해 우리가 할 수 있는 일을 should 를 사용하여 작성하기.

활동 1+2 합쳐서 에세이 쓰기

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조원: 정숙미, 장정은

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조원: 정숙미, 장정은

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1.pre listening 학습지: 단어를 좀더 궁금하게 제시하면 좋겠음. 영어 단어 빈칸 만들기, 단어 뜻 초성 퀴즈 형태로 변형 시키기-> 학생들의 궁금증과 흥미를 더 자극 시킴.

2. listening의 Questions에서 모두 주관식으로 답을 써야 한다면, 단계별로 3문제 정도는 핵심 어휘에 빈칸으로 두고, 2문제 정도느 구(phrase) 표현 넣기, 나머지는 통으로 빈칸(sentences)으로 둬서 단계적 문장쓰기가 가능하게 하면 좋겠다. mixed level 수업에서는 이게 좋을 것 같다.

3. causes와 effects 부분에서 첫 칸은 예시를 먼저 써주면 좋겠다. 그래야 학생들이 답안을 작성할 때 참고가 될 것 같다.

4. today’s note about climate crisis에서 구체적 질문을 제시해주면 학생들이 답을 쓰기가 훨씬 쉬울 것 같다. 예) 오늘 수업에서 내가 기후 위기를 위해 실천ㅎ해야 할 것 실천하지 말아야 할 것을 should shouldn’t를 넣어 작성하기.

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Pre-reading: 여러가지 지붕 사진을 보고 가장 친환경적일 것 같은 지붕 추측하기

Reading: 기사 읽기 및 comprehension check

Post-reading: 기사 내용을 반영하여 '나만의 친환경 지붕 만들기' 조별활동 진행

친환경 지붕 그리기

자신의 디자인을 런던에 판매한다고 가정하고 홍보 소개글 작성하기

이후 조별 투표를 통한 동료평가

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글감: Article 9 (Amazon)

Pre-reading

브레인스토밍-질문 제시(ex. 아마존 숲은 지구 환경에 어떤 역할을 할까요?)

어휘 사전 학습-단어와 뜻 연결 활동

While-reading

내용 확인 - T/F

주요사건, 원인과 결과에 따른 순서 배열

Post-reading

조별 의견 및 생각 정리

'Why is the Amazon forest important for Earth?'

'What actions should humans take to protect it?'

다음 차시 예고

아마존 숲의 사례와 비슷한 한국의 숲의 사례를 찾아보고 의견 나누기.

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Chatgpt를 사용하기 전에 기후난민에

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Chatgpt를 사용하기 전에 기후난민에 대하여 학생들이 생각하고 고민을 나눈 후 생각을 정리해 보는 활동이 있으면 좋을 것 같습니다.

읽기자료에 기후난민이 된 후의 상황들을 보여주는 내용이 추가되면 학생들의 이해를 도울 수 있을 것 같습니다.

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추가 사례를 조사해 발표할

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추가 사례를 조사해 발표할 때 활동지 상으로는 where과 why만 있어서 어떤 내용을 발표하면 좋은지 더 자세하게 명시되어 있으면 좋을 것 같습니다.

동료평가의 평가 기준이 조금 더 명확하면 좋을 것 같습니다.

교사평가에서 평가 영역 중 언어의 적절성에 대한 하위 항목으로 주제와의 관련성이 언급되어 어색한 것 같습니다.

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1. 내용적 단점

동료평가지, 자기평가지를 추가하여 자기성찰하는 과정이 추가되었으면 좋겠음.

2. 교육적 단점

단점 찾을수 없음.

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내용: 4번에서 원인/결과만 찾는데 그러한 결과가 생기게 되는 과정도 간략하게 적을 수 있게끔하면 지금의 기후변화의 심각성 및 이해도를 고양시킬 수 있을 것

교육: 글쓰기 단계에서 내용/형식 면에서 피드백 주는 게 없어 과정 중심 글쓰기가 되지 못하고, 동료 평가가 바로 점수에 직결되는 것이 성적에 예민한 고등학생들게 부담으로 다가올 수 있음.

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본문 내용이 기후변화에 따른 멸종 위기로 인한 생물다양성 저해에 관련된 내용으로 파악되었습니다.

따라서 읽기전 활동 2번이 단순 생물 brainstorming이 아닌 멸종 위기 동물을 찾으면 좋을 것 같습니다.

평가기준에서 '생물다양성의 관련성'이 좀 더 구체적적이면 좋을 것 같습니다.

예를들어 '생물다양성을 저해 시키는 원인/요소가 제시되었는가' 와 같은 의견을 제시해봅니다.

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정유민, 문소진, 공선경

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정유민, 문소진, 공선경

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1.동물에 관한 이야기인데, ‘난민’이라는 표현 써도 괜찮은지?

2.선행조직자 - <보기>에 다양한 animals & plants 표현들 제공하고, 이 중에서 endangered animals & plants를 선택하도록 하는 활동을 하면, 학생들의 부담도 줄이고 학생들의 읽기 주제와 좀 더 관련된 활동을 할 수 있을 듯

3.자기평가 체크리스트 - 참여도에 관한 내용이 대다수 → 핵심 표현을 활용했다 등 학습 내용과 직접 연관이 되는 내용이 있으면 좋을 듯

4. speaking평가 시 발화 속도만 체크 - 비언어적 요소, 유창성, pause와 같은 요소도 평가했으면

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조원: 김도윤, 양은정, 최새봄

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조원: 김도윤, 양은정, 최새봄

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단점 및 보완

말하기 언어기능을 활용할 활동의 부재

target form, 고등학교 수준 적합성 ↓

listening의 comprehension checking 활동이 서술형이라 다소 어렵고, 시간이 오래걸릴 듯합니다! 객관식으로 변경하는건 어떨까요? 혹은 갯수 조정

pre-listening 단어 활동이 조금더 유의미했으면 좋겠습니다! (quiz 형태?!)

자기평가 및 동료평가 시, 평가기준의 모호성

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1. 내용적 단점

1차시 post-reading 활동 중 기후난민을 찾는 활동이 reading의 주제와 연결성이 떨어짐.

2. 교육적 단점

협동학습 요소가 포함된다면 좋을 듯 합니다. (공동체 역량)

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말하기 성취기준에서는 '중심내용을 말할 

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말하기 성취기준에서는 '중심내용을 말할 수 있다'가 핵심인 것 같은데, post-reading에서의 3-2-1 speech activity에서는 '유창성'에 중점을 둔 것 같습니다. 말하기 영역에 있어서 어떤 부분을 목표로 두고 구성된 활동인지가 헷갈리는 것 같습니다.

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1. 내용적 단점:

- 다양한 멸종위기종을 탐구하며 사례 찾기는 좋았지만 멸종위기종을 지키기 위한 노력도 몇가지 탐구하는 활동이 있었으면 좋았을 듯.

2. 교육적 단점:

- pair & group 활동이 좀 더 풍부한 내용과 구체적으로 제시되면 좋았을 듯(개인 사례 찾기 중심이 아닌).

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1. 내용적 단점 - 말하기 활동에서 scaffolding이 더 제공되어야 수준이 낮은 학생들도 참여하는데 부담이 없을 것 같습니다.

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1. 내용적 단점

영상을 보고 답 해야하는 문제의 난이도가 높음

교사평가표 - 쓰기 활동 완성도 부분-> 주관이 개입 될 여지가 있음.

자기평가 체크리스트 - '열심히 탐구했다', '열심히 배웠다' -> 추상적, 주관적, 무조건 높은 점수 줄 가능성 있음.

2. 내용적 보완

객관식으로 변경하여 난이도 조절

정량적인 단어를 추가하여 객관성 확보 (ex. 기후 변화의 해결 방법을 3가지 이상 제시하였다.)

술어를 구체화 (ex. 기후 변화에 관련된 영단어의 의미를 5가지 이상 쓸 수 있다.)

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-동료 평가할 때 Rate 만 제공하는 것보다는 어떤 점을 고려해야 할 지 구체적인 Criteria를 제시해주면 좋겠습니다.

-내용이 어려우니 사전 배경 지식을 쌓을 수 있는 짧은 영상 혹은 수업이 필요할 것 같습니다.

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post-reading으로 앞에서 조사한 6가지 멸종위기종 소개하기 말하기 활동을 하는데 조사한 것을 단순히 보고 말하는 것처럼 느껴져서, 또 말하는 시간을 측정하는 것이 유의미한 학습인지...궁금합니다.

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Article 10 — Youth Climate Litigation Faces Setback but Movement Grows

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Article 10 — Youth Climate Litigation Faces Setback but Movement Grows

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On 24 March 2025 the U.S. Supreme Court declined to hear Juliana v. United States, ending a decade-long effort by 21 young plaintiffs to force federal decarbonisation. While the dismissal closes that docket, lawyers note that Juliana spawned a wave of rights-based climate suits; victories in Montana’s state court and Hawaii’s transport-decarbonisation settlement show the strategy’s evolving reach. Media retrospectives and YouTube explainers chart how the Juliana teens reframed climate change as a constitutional issue of life and liberty, galvanising global youth activism from Europe’s ecocide campaigns to Colombia’s Amazon-protection ruling. Legal scholars now explore narrower “public-trust” claims that may survive higher-court scrutiny, keeping judicial pressure on lagging legislatures.

(https://www.reuters.com/legal/us-supreme-court-will-not-hear-novel-youth-led-climate-change-case-2025-03-24/)

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Article 9 — Amazon Dieback Risk Rises Even at Temporary 1.5 °C Overshoot

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Article 9 — Amazon Dieback Risk Rises Even at Temporary 1.5 °C Overshoot

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A May 2025 Carbon Brief analysis of new Earth-system modelling warns that merely passing 1.5 °C—even briefly—significantly raises the probability of large-scale Amazon dieback. Compound stresses from drought, heat and deforestation create “critical zones” where up to 47 % of the forest could tip toward savannah-like ecosystems by 2050, amplifying regional drying and releasing gigatonnes of carbon. Earlier research suggested a 20–25 % deforestation threshold; the new work underscores that climate forcing interacts with land-use, lowering the margin of safety. The Guardian’s coverage highlights calls for an immediate moratorium on frontier clearing and a global pact to finance forest restoration before feedback loops spin out of control.

(https://www.carbonbrief.org/significant-risk-of-amazon-forest-dieback-if-global-warming-overshoots-1-5c/)

(https://www.theguardian.com/environment/2024/feb/14/amazon-rainforest-could-reach-tipping-point-by-2050-scientists-warn)

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‘Significant’ risk of Amazon forest dieback if global warming overshoots 1.5C - Carbon Brief

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Even passing 1.5C of global warming temporarily would trigger a “significant” risk of Amazon forest “dieback”, says a new study.

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Article 8 — Cool Roofs Emerge as Cities’ Cheapest Heat-Shield

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Article 8 — Cool Roofs Emerge as Cities’ Cheapest Heat-Shield

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UCL modelling of London’s two hottest 2018 days finds that painting or membrane-coating roofs white would cut average outdoor temperatures by 1.2 °C—and up to 2 °C in dense districts—outperforming green roofs, street-level vegetation and solar installations. City-wide adoption could also slash indoor heat stress, lowering mortality during heatwaves without the rebound warming linked to air-conditioner exhausts. As heat-health alerts become routine, municipalities from Los Angeles to Ahmedabad are rolling out cool-roof mandates coupled with subsidies for low-income housing, making passive albedo management a frontline adaptation tool alongside shade trees and reflective pavements.

(https://www.ucl.ac.uk/news/2024/jul/cool-roofs-are-best-beating-cities-heat)

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Cool roofs are best at beating cities’ heat

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Painting roofs white or covering them with a reflective coating would be more effective at cooling cities like London than vegetation-covered “green roofs,” street-level vegetation or solar panels, finds a new study led by UCL researchers.

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Article 7 — Mangroves Deliver an $855 Billion Coastal-Defence Dividend

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Article 7 — Mangroves Deliver an $855 Billion Coastal-Defence Dividend

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A December 2024 UCSC–World Bank study tallies mangroves’ flood-protection value at a staggering USD 855 billion—calculated over 100 years of avoided storm damage. Using high-resolution hydrodynamic models across 121 countries, researchers show that even modest forest belts trim surge heights by 15–30 %, shielding 700,000 km of coastline. From Vietnam’s Mekong Delta to Florida’s Keys, every lost hectare raises local flood-risk premiums, while restoration outperforms seawalls on cost-benefit terms. Policymakers increasingly classify mangroves as capital assets, opening doors to “blue bonds” and insurance-backed conservation where premiums fall if canopy cover is maintained.(https://news.ucsc.edu/2024/12/mangroves-coastal-resilience/)

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Mangroves have been shown to provide $855 billion in flood protection services worldwide, according to a new study from the Center for Coastal Climate Resilience at UC Santa Cruz. The research, conducted by project co-lead, Pelayo Menendez and center director, Michael W. Beck, is featured in the World Bank's 2024 edition of The Changing Wealth of Nations .

, titled Building Coastal Resilience with Mangroves: The Contribution of Natural Flood Defenses to the Changing Wealth of Nations, highlights the essential role mangroves play in protecting coastal communities from floods, storm surges, and erosion, offering significant benefits to both people and national economies. As climate change accelerates the frequency and severity of storms, the need for effective coastal defenses has become increasingly urgent. Traditionally, governments have turned to hard infrastructure like seawalls and levees to guard against floods. However, the center's study reveals that natural ecosystems-particularly mangroves-can be equally, if not more, effective as coastal defenses, while providing additional environmental benefits.

Mangroves were first included as coastal protection assets by the World Bank in the 2021 edition of The Changing Wealth of Nations . This new research expands upon that earlier work by incorporating updated global data from 2020, offering a clearer picture of mangroves' protective value over time. Using advanced flood risk models, Menendez and Beck analyzed mangrove forests in 121 countries, covering 700,000 kilometers of subtropical coastlines.

The study finds that the value of mangroves for flood-risk reduction is rising dramatically, in large part because of increasing populations, wealth and storms on coastlines around the world. From 1996 to 2010, the value of mangroves for flood-risk reduction increased by $130 billion, and from 2010 to 2020, mangrove long-term benefits rose by an additional $502 billion. Despite some declines in mangrove cover-driven by factors such as shrimp farming and coastal development-their value as flood buffers grew as more people and infrastructure came to rely on their protection.

" The results are clear: Mangroves play a critical role in reducing flood risks and should be viewed as valuable natural assets," Menendez said. " They offer cost-effective protection to coastal communities and support national wealth by preserving lives, livelihoods, and infrastructure."

The research goes beyond the environmental importance of mangroves, underscoring their economic value as natural capital assets. The $855 billion figure represents the present value of mangroves' flood protection services, i.e., the benefits of this natural infrastructure over the next 100 years. The countries benefiting most from these services every year include China, Vietnam, Australia, the United States, and India.

The study also shows that while mangrove loss continued from 2010 to 2020, the rate of decline slowed significantly to just 0.66 percent. In that same period, the protective benefits provided by mangroves grew even faster than the overall flood risk. This marks a turning point, with mangroves protecting 61 percent more people and safeguarding 109 percent more capital assets from floods in 2020 compared to a decade earlier.

Countries like Vietnam, Bangladesh, India, China, and Cameroon benefited most from these gains, with mangroves protecting hundreds of thousands of people each year. On the other hand, countries such as Malaysia, Myanmar, and Taiwan saw a decline in mangrove benefits, highlighting the need for increased conservation efforts in these regions.

The findings come at a critical time as countries around the world search for sustainable solutions to rising climate risks. Mangroves offer a natural, cost-effective solution to flood protection, making them an essential component of any climate-adaptation strategy.

As governments and policymakers look to the future, the study provides a compelling case for investing in the conservation and restoration of mangroves. "Protecting and restoring mangroves isn ' t just good for the environment-it ' s a smart economic choice," Beck said. "These ecosystems provide invaluable services that help build resilience against the growing threats of climate change."

The Center for Coastal Climate Resilience has also released these results and data as part of the Coastal Resilience Explorer decision-support tool.

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Mangroves save $855 billion in flood protection globally, new study shows

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Mangroves have been shown to provide $855 billion in flood protection services worldwide, according to a new study from the Center for Coastal Climate Resilience at UC Santa Cruz. The research is featured in the World Bank's 2024 edition of The Changing Wealth of Nations.

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Article 6 — Climate Displacement Hits a Record 83 Million People

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Article 6 — Climate Displacement Hits a Record 83 Million People

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IDMC’s Global Report on Internal Displacement 2025 counts 83.4 million people living uprooted within their own borders—double the figure a decade ago. Weather-related hazards dominated new movements: cyclones in the Bay of Bengal, Sahel droughts pushing pastoralists toward fragile cities, and record Amazon fires. Unlike cross-border refugees, internally displaced persons (IDPs) lack robust legal protection, leaving them in protracted limbo that drains local budgets and erodes social cohesion. The report urges pairing early-warning systems with anticipatory cash transfers so that at-risk families can relocate before disaster strikes, reducing both humanitarian costs and trauma.

(https://www.internal-displacement.org/publications/2025-global-report-on-internal-displacement-grid/?utm_source=chatgpt.com)

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IDMC - Internal Displacement Monitoring Centre

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2025 Global Report on Internal Displacement (GRID)

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Our mission is to provide high-quality data, analysis and expertise on internal displacement with the aim of informing policy and operational decisions that can reduce the risk of future displacement and improve the lives of internally displaced people (IDP) worldwide.

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Article 5 — Methane: The Fast-Track Lever for Near-Term Cooling

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Article 5 — Methane: The Fast-Track Lever for Near-Term Cooling

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Methane drives roughly 30 % of post-industrial warming, and the IEA’s Global Methane Tracker 2025 shows energy-sector leaks, venting and flaring still spew 120 Mt CH₄ yearly—equivalent to all EU CO₂ emissions. Yet the report stresses that existing technologies could cut three-quarters of those emissions by 2030 at net costs near zero because captured gas holds commercial value. The update adds abandoned-well inventories and an interactive map of 159 nations that have joined the Global Methane Pledge, spotlighting laggards whose oil-and-gas infrastructure lacks leak-detection norms. With UNEA negotiations on a standalone methane treaty gaining momentum, 2025 may prove pivotal for translating pledges into binding regulation and satellite-verified compliance.

(https://www.iea.org/reports/global-methane-tracker-2025)

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Article 4 — COP29 Sets Historic—but Costly—Climate-Finance Goal

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Article 4 — COP29 Sets Historic—but Costly—Climate-Finance Goal

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At COP29 in Baku, negotiators hammered out the New Collective Quantified Goal: developed countries will mobilise USD 300 billion annually for developing-nation mitigation and adaptation by 2035, with an aspirational pathway to USD 1.3 trillion from public and private sources. The agreement reframes climate finance from symbolic target to “insurance policy for humanity,” in the words of UNFCCC chief Simon Stiell, yet caveats remain: the pledge is voluntary, front-loaded grant components are undefined, and implementation hinges on reforming multilateral banks. Still, the deal signals that adaptation—long overshadowed by mitigation—is finally priced into global capital flows, potentially unlocking large-scale coastal defences, drought-resilient agriculture and early-warning systems.

(https://unfccc.int/news/cop29-un-climate-conference-agrees-to-triple-finance-to-developing-countries-protecting-lives-and)

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COP29 UN Climate Conference Agrees to Triple Finance to Developing Countries, Protecting Lives and Livelihoods

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UN Climate Change News, 24 November 2024 – The UN Climate Change Conference (COP29) closed today with a new finance goal to help countries to protect their people and economies against climate disasters, and share in the vast benefits of the clean energy boom. With a central focus on climate finance, COP29 brought together nearly 200 countries in Baku, Azerbaijan, and reached a breakthrough agreement that will: Triple finance to developing countries, from the previous goal of USD 100 billion annually, to USD 300 billion annually by 2035. Secure efforts of all actors to work together to scale up finance to developing countries, from public and private sources, to the amount of USD 1.3 trillion per year by 2035. Known formally as the New Collective Quantified Goal on Climate Finance (NCQG), it was agreed after two weeks of intensive negotiations and several years of preparatory work, in a process that requires all nations to unanimously agree on every word of the agreement. “This new finance goal is an insurance policy for humanity, amid worsening climate impacts hitting every country,” said Simon Stiell, Executive Secretary of UN Climate Change. “But like any insurance policy – it only works – if premiums are paid in full, and on time. Promises must be kept, to protect billions of lives.” “It will keep the clean energy boom growing, helping all countries to share in its huge benefits: more jobs, stronger growth, cheaper and cleaner energy for all.” The International Energy Agency expects global clean energy investment to exceed USD 2 trillion for the first time in 2024. The new finance goal at COP29 builds on significant strides forward on global climate action at COP27, which agreed an historic Loss and Damage Fund, and COP28, which delivered a global agreement to transition away from all fossil fuels in energy systems swiftly and fairly, triple renewable energy and boost climate resilience. COP29 also reached agreement on carbon markets – which several previous COPs had not been able to achieve. These agreements will help countries deliver their climate plans more quickly and cheaply, and make faster progress in halving global emissions this decade, as required by science. Important agreements were also reached on transparent climate reporting and adaptation as summarized below. Stiell also acknowledged that the agreement reached in Baku did not meet all Parties’ expectations, and substantially more work is still needed next year on several crucial issues. “No country got everything they wanted, and we leave Baku with a mountain of work to do,” said Stiell. “The many other issues we need to progress may not be headlines but they are lifelines for billions of people. So this is no time for victory laps, we need to set our sights and redouble our efforts on the road to Belem.” The finance agreement at COP29 comes as stronger national climate plans (Nationally Determined Contributions, or NDCs) become due from all countries next year. These new climate plans must cover all greenhouse gases and all sectors, to keep the 1.5°C warming limit within reach. COP29 saw two G20 countries – the UK and Brazil – signal clearly that they plan to ramp up climate action in their NDCs 3.0, because they are entirely in the interests of their economies and peoples. “We still have a very long road ahead, but here in Baku we took another important step forward,” said Stiell. “The UN Paris Agreement is humanity’s life-raft; there is nothing else. So here in Baku and all of the countries represented in this room we’re taking that journey forward together.” A brief summary of other key achievements at COP29 follows below. Article 6 of the Paris Agreement A notable achievement during the past two weeks was the progress made on carbon markets. After nearly a decade of work, countries have agreed on the final building blocks that set out how carbon markets will operate under the Paris Agreement, making country-to-country trading and a carbon crediting mechanism fully operational. On country-to-country trading (Article 6.2), the decision out of COP29 provides clarity on how countries will authorize the trade of carbon credits and how registries tracking this will operate. And there is now reassurance that environmental integrity will be ensured up front through technical reviews in a transparent process. On day one of COP29, countries agreed standards for a centralized carbon market under the UN (Article 6.4 mechanism). This is good news for developing countries, who will benefit from new flows of finance. And it is particularly good news for least developed countries, who will get the capacity-building support they need to get a foothold in the market. This mechanism, known as the Paris Agreement Crediting Mechanism, is underpinned by mandatory checks for projects against strong environmental and human rights protections, including safeguards that ensure a project can’t go ahead without explicit, informed agreement from Indigenous Peoples. It also allows anyone affected by a project to appeal a decision or file a complaint. Under the text agreed on Article 6.4, there is a clear mandate for the UN carbon market to align with science. It tasks the Body getting this market up and running to consider the best available science across all work going forward. The work on carbon markets doesn’t stop in Baku. The Supervisory Body setting up the new carbon crediting mechanism has been handed a long 2025 to-do list by Parties and will continue to be accountable to them. Transparency Transparent climate reporting made big strides forward in Baku, building a stronger evidence base to strengthen climate policies over time, and helping to identify financing needs and opportunities. To date, 13 Parties have now submitted their first Biennial Transparency Reports (BTR) – due from all Parties by the end of the year. Andorra, Azerbaijan, the European Union, Germany, Guyana, Japan, Kazakhstan, Maldives, Netherlands, Panama, Singapore, Spain, and Türkiye have led the way on transparent climate reporting, and set an example for others to follow. The list of received BTRs is continuously being updated here. In addition, all transparency negotiating items concluded successfully at COP29, with Parties expressing their appreciation for the timely completion of the Enhanced Transparency Framework (ETF) reporting tools, the technical trainings, the support provided to developing countries for reporting under the ETF that took place in 2024, and the successful launch of the review process. A total of 42 events were organized under #Together4Transparency, a UNFCCC collaborative initiative that promotes climate transparency with Parties and non-Party stakeholders. These events emphasized the vital role of transparency in preparing NDCs and net-zero pathways, as well as in recognizing climate action from non-Party stakeholders. Events included high-level sessions, mandated events and training sessions to prepare countries for their BTRs, as well as to equip technical experts for the upcoming review process. The critical role of REDD+ was recognized through a £3 million pledge by the UK International Forest Unit to support UN Climate Change’s work over four years. This funding will bolster REDD+ activities in many countries, enabling the secretariat to create dedicated spaces for REDD+ experts to engage in technical dialogue. These efforts are expected to enhance the transparency and implementation of REDD+, in line with the Global Stocktake objective to halt and reverse deforestation and forest degradation by 2030. Adaptation COP29 was an important moment for adaptation, with the delivery of several key outcomes. The COP decision on matters relating to the least developed countries (LDCs) contains a provision for the establishment of a support programme for the implementation of National Adaptation Plans (NAPs) for the LDCs. Parties extensively discussed the second five-year assessment of progress to formulate and implement NAPs, and will continue that in June 2025. A High-Level Dialogue on National Adaptation Plans convened ministers from least developed countries and small island developing States, financial experts and international donors to address the growing urgency of climate adaptation. Their discussions focused on innovative financing, technical support, and accelerated action to meet the 2025 submission deadline for NAPs. The event concluded with a strong call to action to expedite NAPs and translate plans into tangible outcomes. The outcome on the global goal on adaptation sets a clear path forward on the road to COP30 for the indicators work programme, providing a process for experts to continue their technical work before passing the baton to Parties. COP29 also launched the Baku Adaptation Road Map and Baku high-level dialogue on adaptation to enhance the implementation of the UAE Framework. Finally, the outcome raises ambition by agreeing to continue unpacking transformational adaptation moving forward. COP29 took a decisive step forward to elevate the voices of Indigenous Peoples and local communities in climate action, adopting the Baku Workplan and renewing the mandate of the Facilitative Working Group (FWG) of the Local Communities and Indigenous Peoples Platform (LCIPP). The adopted decision acknowledges the progress made by the FWG in fostering collaboration among Parties, Indigenous Peoples and local communities, and underscores the leadership of Indigenous Peoples and local communities in addressing the climate crisis. Gender and climate change Countries agreed a decision on gender and climate change, extending the enhanced Lima Work Programme on Gender and Climate Change for another 10 years, reaffirming the importance of gender equality and advancing gender mainstreaming throughout the convention. They also agreed to develop a new gender action plan for adoption at COP30, which will set the direction for concrete implementation. Civil society participation, children and youth World leaders at COP29 were joined by civil society, subnationals, business, Indigenous Peoples, youth, philanthropy, and international organizations. More than 55,000 people attended COP29 to share ideas, solutions, and build partnerships and coalitions. The decisions taken at COP29 also reemphasize the critical importance of empowering all stakeholders to engage in climate action; in particular under Action for Climate Empowerment (ACE). Parties recalled the importance of integrating ACE elements into national climate change policies, plans, strategies and action, and noted the secretariat’s compendium of good practices for integrating ACE elements into NDCs. COP29 marked a significant milestone as dedicated spaces were created to ensure the meaningful participation of children within the Youth-led Climate Forum for the first time. Four children, including the youngest at just 10 years old, took on roles as moderators and speakers, engaging directly with Parties and observer organizations. Their participation highlighted the importance of inclusivity and intergenerational collaboration in driving climate action. In parallel with the formal negotiations, the Global Climate Action space at COP29 provided a platform for governments, businesses and civil society to collaborate and showcase their real-world climate solutions. An overview and summary of these can be found here. The High-Level Champions, under the Marrakech Partnership for Global Climate Action, launched their 2024 Yearbook of Global Climate Action at COP29, showing that climate action by non-Party stakeholders, including businesses, investors, sub-national actors and civil society, is driving progress towards the goals of the Paris Agreement, and that their engagement is more crucial than ever. More information Read a transcript of UN Climate Change Executive Secretary Simon Stiell’s closing speech at COP29 here (also available in Arabic, French, Portuguese, Russian and Spanish). Read the COP29 decision texts here. Find UN Climate Change tracked climate action announcements made at COP29 here. For media enquiries, please contact press@unfccc.int

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Article 3 — Solar and Wind Move Centre-Stage in Global Power Mix

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Article 3 — Solar and Wind Move Centre-Stage in Global Power Mix

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The IEA’s Renewables 2024 outlook projects annual clean-power additions jumping from 666 GW in 2024 to almost 935 GW by 2030. Solar PV and wind will account for 95 % of that growth, their costs now lower than both fossil and non-fossil alternatives across most regions. While hydropower still grows 20-30 GW a year, and bioenergy around 12 GW, the headline is displacement: in 2024 solar–wind generation is set to surpass coal on the global grid for the first time, marking a structural pivot in electricity markets. Governments’ pledge at COP28 to triple global renewable capacity by 2030 looks technically feasible—if permitting and grid-integration bottlenecks are cleared.

(https://www.iea.org/reports/renewables-2024/electricity)

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Article 2 — 2025’s Extreme Weather: Attribution Science Finds Climate Fingerprints Everywhere

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Article 2 — 2025’s Extreme Weather: Attribution Science Finds Climate Fingerprints Everywhere

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World Weather Attribution’s rapid analyses show that events once dubbed “acts of God” now bear human fingerprints. June heat across England, Iceland and Greenland, May’s New South Wales floods, and April’s Mississippi Valley storms were all made at least two to five times more likely—and in some cases markedly more intense—by anthropogenic warming. In the UK, a Guardian analysis projects the current June heat will cause nearly 600 excess deaths, mainly among older urban residents, underscoring how small temperature shifts translate into large health tolls. Such real-time attribution is helping local authorities connect preparedness plans—cooling centres, flare-up medical staffing—to specific climate drivers instead of statistical averages, making adaptation more targeted.

(https://www.theguardian.com/environment/2025/jun/21/heatwave-expected-deaths-england-and-wales-analysis?utm_source=chatgpt.com)

(https://www.worldweatherattribution.org/2025/)

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Almost 600 people are expected to die early in the heatwave roasting England and Wales, a rapid analysis has found.

The surge in deaths would not be occurring without human-caused global heating, the scientists said, with temperatures boosted by 2C-4C by the pollution from fossil fuels.

Premature deaths will occur across the two countries but the highest mortality rates are expected in London and the West Midlands. Most of the deaths - 85% - will be people over 65 years old, who are more vulnerable to the extreme heat. People in inner-city homes are also at high risk.

More than 10,000 people died before their time in summer heatwaves between 2020 and 2024, according to the UK Health Security Agency (UKHSA). The government's preparations to protect people from the escalating impacts of the climate crisis were condemned as " inadequate, piecemeal and disjointed " by official advisers in April.

The 32C heat that will be endured by people in the south-east of England on Saturday will have been made 100 times more likely by the climate crisis, scientists said on Friday.

"Heatwaves are silent killers - people who lose their lives in them typically have pre-existing health conditions and rarely have heat listed as a contributing cause of death," said Dr Garyfallos Konstantinoudis, at Imperial College London, who is part of the team that estimated the number of deaths.

"This real-time analysis reveals the hidden toll of heatwaves and we want it to help raise the alarm," he said. "Heatwaves are an under-appreciated threat in the UK and they're becoming more dangerous with climate change."

Prof Antonio Gasparrini, at the London School of Hygiene & Tropical Medicine (LSHTM) and also part of the analysis team, said: "Increases of just a degree or two can be the difference between life and death.

"When temperatures push past the limits populations are acclimatised to, excess deaths can increase very rapidly. Every fraction of a degree of warming will cause more hospital admissions and heat deaths, putting more strain on the NHS."

The analysis used decades of UK data to determine the relationship between temperatures and heat deaths in more than 34,000 areas across England and Wales.

The researchers combined this with high-resolution weather forecasts to estimate that there will be about 570 deaths between Thursday and Sunday, with 129 in London. The number could be an underestimate, they said, as people were less prepared for heatwaves in early summer.

Dr Malcolm Mistry, at LSHTM, said: "Exposure to temperatures in the high 20s or low 30s may not seem dangerous, but they can be fatal, particularly for people aged over 65, infants, pregnant people, and those with pre-existing health conditions."

The UKHSA sounded the alarm on Thursday with an amber heat-health alert, also warning of "a rise in deaths" and "significant impacts" to health and social care services. The alert is expected to remain in force until 9am on Monday.

Dr Lorna Powell, an NHS urgent care doctor in east London, said: "We are seeing cases of heat-related illnesses rising.

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"Heat exhaustion can quickly trigger more serious illnesses, as dehydration sets in and the cardiovascular system becomes overwhelmed.

"We must stop burning coal, oil and gas if we are to stabilise our climate and prevent scores of preventable health issues, hospital visits and deaths."

The UKHSA recommends people keep out of the sun between 11am and 3pm on the hottest days, drink plenty of water, and look out for older people. A recent study estimated that 80% of UK homes overheat in the summer.

The hot sun has also led to a warning of high ozone air pollution in London on Saturday, with people with lung problems advised to limit exercise.

The climate crisis drove the annual global temperature in 2024 to a new record and carbon dioxide emissions from coal, oil and gas are still rising. That means heatwaves will get ever more intense and frequent.

A recent report by the UK climate change committee estimated that heat-related deaths could rise to more than 10,000 a year by 2050 if global temperatures rise to 2C above preindustrial levels.

Globally, extreme heat is more deadly than floods, earthquakes and hurricanes combined, taking about 500,000 lives a year, according to a report by the insurer Swiss Re.

"Extreme heat events are more dangerous than natural catastrophes in terms of human lives lost, yet the true cost is only starting to come to light," said Nina Arquint, a corporate solutions chief executive at Swiss Re.

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Current heatwave 'likely to kill almost 600 people in England and Wales'

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Surge in deaths would not be occurring without human-caused global heating, scientists say as analysis published

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Article 1 — Record Atlantic Marine Heatwaves Are Re-shaping Ocean Climate

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Article 1 — Record Atlantic Marine Heatwaves Are Re-shaping Ocean Climate

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The North Atlantic’s extraordinary 2023 marine heatwave, dissected in a June 2025 Nature study, smashed temperature records across almost the entire basin. Researchers traced the spike not to deep-ocean heat transport but to an unusually shallow surface-mixed layer combined with weak winds that limited vertical mixing. With only a few metres of water to warm, modest atmospheric anomalies translated into sea-surface temperatures 1–3 °C above normal, fuelling European land heat and flooding and stressing marine ecosystems from plankton to cod. The authors warn that mixed layers have shoaled for decades; under continued greenhouse forcing, extreme Atlantic heatwaves will “worsen in frequency and intensity,” compounding coastal storm rainfall and accelerating global mean-temperature records.

(https://www.nature.com/articles/s41586-025-08903-5)

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Abstract

North Atlantic Ocean circulation and temperature patterns profoundly influence global and regional climate across all timescales, from synoptic1 to seasonal2,3,4, decadal5, multidecadal6,7 and beyond8,9. During 2023, an extreme and near-basin-scale marine heatwave developed during Northern Hemisphere summer, peaking in July. The warming spread across virtually all regions of the North Atlantic, including the subpolar ocean, where a cooling trend over the past 50-100 years has been linked to a slowdown in the meridional overturning circulation10,11. Yet the mechanisms that led to this exceptional surface ocean warming remain unclear. Here we use observationally constrained atmospheric reanalyses alongside ocean observations and model simulations to show that air-sea heat fluxes acting on an extremely shallow surface mixed layer, rather than anomalous ocean heat transport, were responsible for this extreme ocean warming event. The dominant driver is shown to be anomalously weak winds leading to strongly shoaling (shallowing) mixed layers, resulting in a rapid temperature increase in a shallow surface layer of the North Atlantic. Furthermore, solar radiation anomalies made regional-scale warming contributions in locations that approximately correspond to some of the region's main shipping lanes, suggesting that reduced sulfate emissions could also have played a localized role. With a trend towards shallower mixed layers observed over recent decades, and projections that this will continue into the future, the severity of North Atlantic marine heatwaves is set to worsen.

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Marine heatwaves are characterized by sustained periods of abnormally warm ocean temperatures in a given region12,13, with the potential for severe damage to marine ecosystems14 and reliant human systems15. Marine heatwaves can also influence atmospheric conditions, including altering weather patterns and affecting land-based heatwaves in adjacent regions16,17. The 2023 summertime marine heatwave in the North Atlantic was associated with extreme heatwaves over large areas of Europe, particularly during July, and was so large in magnitude that it was a substantial contributor to record global mean temperatures that developed that year (ref. 18). There were also severe storms and flooding rains across parts of Europe during June-September, probably exacerbated by enhanced evaporation and higher atmospheric moisture content upstream over the hotter-than-average North Atlantic19. Year-long precipitation anomalies for 2023 reveal many regions across Europe and the United Kingdom with total rainfall in the top 10-20% compared with 1991-2020 (ref. 18). Given the potential for North Atlantic marine heatwaves to cause substantial ecosystem damage and bring about severe heatwaves and flooding rains over parts of Europe and other regions, it is important to understand the drivers of the extraordinary 2023 event.

The 2023 North Atlantic marine heatwave

An analysis of daily mean North Atlantic sea surface temperature (SST) anomalies during 2023 relative to previous years over the satellite measurement era is presented in Fig. 1a. During the Northern Hemisphere summer of 2023, the North Atlantic upper ocean developed exceptionally strong warming, with SST spiking well above previous record temperatures during June and July and remaining well above record levels for the remainder of the year. This temperature evolution is reproduced by the ocean models we later analyse in this study (Fig. 1a). A breakdown of the total 2023 North Atlantic warming into separate western and eastern contributions reveals considerable geographic variations in surface heating (dashed red lines in Fig. 1b), with rapid anomalous warming observed in the eastern North Atlantic during June, followed by a surge in western North Atlantic temperature anomalies during July.

a, Observed daily mean SST anomalies (°C) averaged between the equator and 60° N, with years indicated by colour shaded lines, from dark blues (earliest years) to pale blues (most recent years) and 2023 indicated in bold red. Observed estimates of SST are taken from ERA5. Simulated SST anomalies during 2023 are shown for the model runs forced by ERA5 and JRA55 in black and grey curves, respectively. b, Decomposition of total North Atlantic SST anomalies into eastern and western components. The thin red dotted and dashed lines indicate daily averaged SST anomalies for 2023 averaged separately east and west of 40° W, respectively. c- f, Observed estimates of monthly average SST anomalies during May-August 2023, relative to monthly means calculated over the period 1981-2010.

The geographic distribution of anomalous ocean warming during May-August 2023 (Fig. 1c-f) shows that, although initial modest warming west of Europe and North Africa occurred in May, even greater rates of anomalous warming occurred during June, covering much of the eastern North Atlantic with record warm temperatures, at more than 2 °C above average relative to 1981-2010. During July, some of this northeast Atlantic warming abated, whereas-at the same time-the northwestern region flared up with exceptionally warm SST anomalies, extending from the North American coast around Nova Scotia and into the Labrador Sea. Further warming of the oceans adjacent to Greenland and in Hudson Bay occurred during August.

An examination of the atmospheric circulation and surface wind speed anomalies (Fig. 2) reveals a coincidence between regions of anomalously weak winds and the regions of anomalous North Atlantic surface warming during June and July described above. The anomalously weak winds during June 2023 were largely associated with a weakening of the climatological high-pressure system over the North Atlantic (Extended Data Fig. 1). This weakening of the prevailing anticyclonic circulation is consistent with previously identified teleconnections from a developing El Niño-Southern Oscillation and warmer waters in the tropical eastern Pacific, which act to reduce the northeast trade winds in the Atlantic20,21. Further climate or synoptic-scale anomalies probably also played a role, given that the exceptional wind reduction peaked only in June (Extended Data Fig. 2a). During July 2023, weakened winds then became more pronounced in the northwest Atlantic (Fig. 2c and Extended Data Fig. 2b), coinciding with that region's surge in SST anomalies (compare Fig. 1e with Fig. 1d), whereas to the east, the weakened wind field contracted. At the same time, an anomalous air flow from the north led to a region of SST cooling west of the British Isles. During August, virtually all of the regions that remained anomalously warm coincided with weaker than average winds (Fig. 2d). Relative to the satellite era since 1979, the area-averaged wind speed over the eastern North Atlantic was the lowest ever recorded for June during 2023 and, for the western North Atlantic, the joint lowest ever recorded for July during 2023 (Extended Data Fig. 2), coinciding with the largest surges in SST anomalies seen in Fig. 1b.

a- d, Wind speed anomalies (m s −1) are shaded and calculated relative to the 1981-2010 mean. Wind vector anomaly scale is shown in panel a, 5 m s −1. Observed estimates of wind speed and wind vectors are taken from ERA5. The +1 °C and −1 °C SST anomaly contours from Fig. 1 are overlaid in red and blue, respectively. To avoid ambiguity, the regions of anomalous warm SST are indicated by the small red tick marks added to the inner side of the +1 °C anomaly contour.

Reduced winds over the ocean affect air-sea heat fluxes in several ways. First, both latent and sensible ocean heat loss typically decrease, as these exchanges of heat scale with the square of surface wind speed22. Reduced ocean evaporation can, in turn, contribute to reduced low-level and mid-level cloudiness, which was indeed the case over regions of low wind speed during June and July 2023 (Extended Data Fig. 3). Furthermore, weakened winds over the ocean may lead to reduced surface albedo as a result of reduced sea-spray aerosols and reduced white-capping from breaking waves23,24, which allows more incoming solar radiation to enter the ocean. In combination with clearer skies, low wind speeds are thus conducive to an increase in the net surface heat flux entering the ocean. Once the surface layer of the ocean has warmed, this tends to reduce atmospheric boundary layer stability and increase mixing of dry air at low levels, reducing the low-level relative humidity and leading to fewer low-level clouds. In summer, this leads to an amplifying feedback with further surface ocean warming.

The observed net surface heat flux anomalies during summer 2023 as well as the anomalies in the two dominant components-incoming shortwave radiation and outgoing latent heat fluxes-are shown in Extended Data Fig. 4. This breakdown into constituent terms reveals that the regions of anomalous net ocean heat gain are primarily associated with above-average incoming solar radiation (Extended Data Fig. 4, middle column), with an extra contribution from more localized regions of lower-than-average latent heat loss (Extended Data Fig. 4, right column). Variations resulting from outgoing longwave and sensible heat fluxes are much smaller, with anomalies generally less than about 10 W m −2 for most regions (figure not shown). Overall, the regions of greatest warming during June in the eastern North Atlantic and July in the western North Atlantic correspond to regions of anomalous surface ocean heat gain (Extended Data Fig. 4). By contrast, there is anomalous ocean heat loss across much of the eastern North Atlantic during July (Extended Data Fig. 4g), which has been linked to a warming of the atmosphere adjacent to western Europe that contributed to the hot temperatures and heatwaves seen across the region during July19. These enhanced evaporative fluxes might also have contributed to the anomalous rainfall that occurred over Europe during July19.

As well as the air-sea heat exchange processes described above, the weakened northeasterly trade winds extended over the Sahara Desert, particularly during June 2023 (Fig. 2b). Weakened northeast trades have previously been linked to a reduction in dust transport westward into the Atlantic Ocean25. Such a reduction in Saharan dust transport has been associated with warm SST anomalies because dust acts to scatter incoming solar radiation before it reaches the ocean surface26. Another factor proposed to account for the increase in incoming solar radiation in 2023 is reduced sulfate aerosol emissions along the main shipping lanes following the International Maritime Organization 2020 agreement27,28. However, recent work has suggested that this signal may be difficult to detect on a basin scale given the large interannual variability in Earth's energy imbalance and the short observational record since these changes came into effect29. Although this topic remains an area of continued research, we will later show that, in terms of the record-breaking basin-wide warming of the surface North Atlantic, the relative contribution of solar radiation anomalies was less than the impact of shoaling mixed layers.

During summer, the surface layer of the ocean becomes well stratified, with warm surface waters overlying colder deep waters. Mixed layer depth (MLD) during this season is thus largely set by the strength of surface winds, which act to mix and overturn surface waters within the wind-driven turbulent mixed layer. It is little surprise then that the regions of record-low wind speeds during summer 2023 largely coincided with unusually shallow mixed layers (Figs. 2 and 3; other ocean reanalysis products are compared in Extended Data Fig. 10). In particular, during June 2023, anomalously shallow MLDs extended from the tropical North Atlantic north to regions west of Europe, with basin averaged MLD anomalies reaching around three standard deviations shallower than average (Fig. 3e; that is, a 3 σ event, with a likelihood of occurrence of only 0.13% assuming that the MLD anomalies are normally distributed about the mean). Shallow mixed layers can then be seen over the northwest Atlantic during July 2023, coinciding with a region of weaker-than-average winds (Fig. 2c). Part of this region may have also experienced further mixed layer shoaling owing to meltwater input from the nearby Greenland ice sheet (Extended Data Fig. 5), with 2023 being the third highest melt season since passive microwave records began 45 years ago30. Melt was particularly high in the southwest of Greenland, with added freshwater entering the Labrador Sea during summer 2023 (ref. 30). This region of added meltwater coincided with strong freshening and warming, illustrating that the impact of meltwater on the ocean is not primarily through its temperature but through the dynamical effects of its low salinity and, therefore, low density (and shallow mixed layers). An analysis of the ERA5-forced model-simulated MLD anomalies reveals an overall consistent pattern of record MLD shoaling across the North Atlantic during the summer months of 2023 (Extended Data Fig. 6).

a- d, MLD anomalies (shaded) are normalized by one standard deviation (SD) for each month and location and calculated relative to the 1981-2010 mean. The MLD is calculated using a density threshold criterion of 0.125 kg m −3, relative to surface density, using temperature and salinity data from the IAPv3 climatology ( Methods). The ±1 °C SST anomaly contours from Fig. 2 are overlaid in red and blue, respectively. e, Time series of North Atlantic area-averaged MLD anomalies (equator to 60° N), with years indicated by colour shaded lines, from dark blues (earliest years) to pale blues (most recent years) and 2023 indicated in bold red. The thin red dotted and dashed lines indicate monthly averaged MLD anomalies for 2023, averaged separately east and west of 40° W, respectively.

A monthly analysis of observed MLD in the IAPv3 dataset over the past four decades (Fig. 3e) shows a progressive shoaling of mixed layers during summer, with the 2023 MLD anomalies substantially shallower than that expected from the long-term trends alone (Extended Data Fig. 7a). This can also be seen when examining basin-averaged upper ocean temperature stratification and annual mean temperature profiles observed since 1980 (Extended Data Figs. 7b and 8). The IAPv3 shoaling trend averaged over June-August is −0.58 m per decade during 1980-2023, with average North Atlantic MLD in the summer of 2023 (20.6 m) more than 7 m shallower than the peak summer MLD value of 27.9 m observed in the early 1990s (Extended Data Fig. 7a) and around 20% shallower than the climatological summer mean during 1980-2000 (25.1 m). This corresponds to a marked shoaling of the summer mixed layer, reducing the thermal inertia of the surface ocean. Averaged over the North Atlantic, ocean mixed layers were around four standard deviations shallower than average during July 2023 (a 4 σ event, with a likelihood of occurrence of just 0.003% assuming normally distributed MLD anomalies). During a season of net ocean heat gain, these shallow mixed layers readily warm because less incoming energy is needed to heat a thin surface layer. This triggers an amplifying feedback in which the original ocean warming and stratification, left undisturbed by weak surface winds, leads to further warming and higher levels of stratification (and even shallower mixed layers). A very rapid warming set in as a consequence during June and July 2023.

Surface temperature budget

To quantify the relative importance of the various driving factors, we next examine a temperature budget of the surface mixed layer during the peak warming months using an ocean model simulation forced by atmospheric reanalysis fields. Two model simulations were evaluated ( Methods), with both capturing the main features of North Atlantic anomalous warming during summer 2023 (Fig. 1a). Here we analyse the ocean model forced by ERA5 atmospheric reanalysis fields; similar results are obtained from the JRA55-forced simulation (figures not shown). Observational estimates of the mixed layer temperature (MLT) budget can also be reconstructed, including all components of the surface air-sea heat flux terms, but data are unavailable to resolve the ocean advection and mixing terms, and larger uncertainty exists owing to the sparse measurement record ( Methods). Nonetheless, both the observationally derived estimate and the two model simulations show overall agreement in the results obtained from the MLT budget calculations described below.

Figure 4a shows an analysis of the ERA5-forced model-simulated total North Atlantic surface warming during May-August 2023, decomposed into anomalies in the MLT tendencies (°C per month), alongside other budget terms relative to the 1981-2010 climatological mean. Note that, because the budget is formulated as a MLT budget, anomalies in each term (for example, the warming due to air-sea heat fluxes) can result from anomalies in the MLD alone or in combination with anomalies in the heat source terms themselves. The geographic distribution of the MLT tendency term is also plotted for June-July 2023 in Fig. 4 (lower panels), separated into anomalies in warming due to net air-sea heat fluxes and anomalies in warming due to the combined effects of ocean circulation and mixing. The corresponding observationally based MLT budget derived from ERA5 air-sea heat fluxes combined with Argo float data and other hydrographic measurements is included in Fig. 5a.

a, Anomalous surface warming over the North Atlantic (equator to 60° N) during May-August decomposed into each surface heat flux term (and the net surface heat flux), the net vertical mixing and entrainment terms and the advection plus other minor terms. The total anomalous MLT tendency (red bars) is primarily a balance between net surface heat flux anomalies (orange bars) and cooling anomalies at the base of the mixed layer due to vertical mixing and entrainment (green bars). The shortwave radiation anomalies are decomposed into anomalies due to MLD variations alone (MLD′), anomalies due to surface heat flux variations alone ( Q SW′) and anomalies due to the radiative flux through the base of the mixed layer ( Q SW,H′). b- g, June and July anomalous mixed layer warming ( b, e) versus that due to anomalies in net surface heat fluxes ( c, f) and total ocean advection, mixing and entrainment ( d, g). Units are °C per month throughout. The net surface heat flux anomalies are calculated for the mixed layer, subtracting out shortwave radiation penetration at the base of the mixed layer ( Methods). The model simulation shown here is that forced by the ERA5 atmospheric reanalysis fields. Similar results are obtained from the JRA55-forced ocean model simulation. Note that this analysis calculates the MLT budget terms centred on each month, while the warming discernible in Fig. 1c-f is from one month to the next (that is, between monthly averages, centred at the start of each month). Also note that this analysis does not include the effects of interannual variability in shipping emissions. See Methods and Extended Data Fig. 11 for further details.

a, Observed anomalous surface warming over the North Atlantic (equator to 60° N) during May-August, decomposed into each surface heat flux term, with the residual terms including unresolved mixing, entrainment, advection plus uncertainty in the reanalysis estimates. Anomalies are calculated relative to the 1981-2010 climatological mean. The budget terms are calculated using ERA5 air-sea heat fluxes combined with MLD and temperature derived from the IAPv3 climatology ( Methods). The shortwave radiation anomalies are decomposed into anomalies due to MLD variations alone (MLD′), anomalies due to surface heat flux variations alone ( Q SW′) and anomalies due to the radiative flux through the base of the mixed layer ( Q SW,H′). The analysis presented here does not include the effects of interannual variability in shipping emissions. See Methods and Extended Data Fig. 11 for further details. b, The schematic shows the progression of North Atlantic surface warming during May, June, July and August. Dashed white line indicates the MLD. Shallow mixed layers in May 2023 are part of a long-term trend towards shallower springtime stratification in the North Atlantic. Rapid warming and shoaling of mixed layers in the northeast Atlantic during June was driven by anomalous weak winds and clear skies, leading to much shallower than average mixed layers. That tendency continued during July in the northwest Atlantic. During August, atmospheric winds returned to normal or above-average strength in some regions, leading to anomalous ocean heat loss and atmospheric warming in those areas, as well as anomalous mixing and detrainment of surface layer heat across the base of the mixed layer.

The model and observed MLT budgets both reveal that the record surface ocean warming was because of a combination of anomalously shallow mixed layers, clear skies and high incoming shortwave radiation (Figs. 4 and 5a). However, a breakdown of the relative roles of anomalous surface heat fluxes versus anomalous shallow MLDs (bars shown in the Q SW term; Figs. 4a and 5a) reveals that the exceptionally shallow mixed layers played the dominant role in the basin-wide warming, such that the marine heatwave would have been almost as severe had air-sea heat fluxes been no different to the climatological summer mean. By contrast, solar radiation anomalies had a more localized impact. A regional analysis reveals that the main areas where above-average incoming solar radiation played the dominant role (Extended Data Fig. 9) coincided with reduced low-level to mid-level cloud cover (Extended Data Figs. 3 and 4). Some of these regions also coincide with locations of the main shipping lanes in which reduced sulfate emissions have been linked to clearer skies and higher incoming solar radiation31,32,33,34. Part of the reduction in low-level cloud cover could thus be linked to indirect effects from reduced shipping emissions35. Overall, our regional temperature budget analysis demonstrates that, although the basin-wide surface warming was driven primarily by shoaling mixed layers, reduced shipping emissions could have played a localized role in the 2023 North Atlantic marine heatwave. Uncertainty remains nonetheless in quantifying the direct and indirect radiative impacts of reduced shipping emissions32,35, with other factors also potentially contributing to these shortwave radiation anomalies, such as reduced cloud cover due to variations in weather and climate modes, proximity to the solar maximum (reached in 2024), surface albedo effects, and atmospheric water vapour35.

The regions that cannot be explained by the air-sea heat flux terms include the Gulf Stream and its extension, where enhanced northward advection of warm tropical surface waters dominates (Fig. 4). Elsewhere, in the regions indicated by blue shading in the model ocean circulation and mixing terms (Fig. 4d,g), the anomalous surface heating exceeds the amount of energy required to account for the surface layer warming. In these regions, there is enhanced vertical heat loss across the base of the summer mixed layer, owing to both shortwave penetration effects as well as anomalous vertical entrainment and mixing (Fig. 4a). This results in substantial heating of the water column below the mixed layer, as can also be seen in the observed temperature-depth anomaly profiles (Extended Data Fig. 8, lower panels). Overall agreement can be seen in the observational MLT budget terms, with shoaling mixed layers the dominant factor contributing to the record-breaking basin-wide marine heatwave, alongside a regional contribution from anomalous incoming shortwave radiation (Fig. 5a and Extended Data Fig. 9).

Mechanisms driving the extreme heating

A schematic outlining the progression of surface mixed layer warming over the Northern Hemisphere summer in the Atlantic Ocean is shown in Fig. 5b. During June in the east and then subsequently July in the west, record weak winds over the surface of the ocean led to the shallowest ever recorded MLDs in those regions. Coupled with clearer-than-average skies, lower cloud albedo27 and net heat gain across the air-sea interface, this led to an amplifying feedback that produced very shallow and very warm mixed layers across much of the North Atlantic Ocean. Although the progression of surface warming played out separately over the eastern North Atlantic during June and then in the northwestern North Atlantic during July, the same overall mechanism seems to have controlled both bursts of surface warming; namely, surface heating driven by anomalously weak winds, clear skies and shallow mixed layers. Reduced sulfate aerosol emissions along the main Atlantic shipping lanes27,28,31,32 has also been proposed as a driver of the record-breaking 2023 warming. By recalculating the North Atlantic temperature budget anomalies assuming (1) climatological air-sea heat fluxes and (2) climatological MLDs (Figs. 4a and 5a), we have demonstrated that, at a basin scale, shallow mixed layers resulting from anomalous weak winds were the dominant driver of the record basin-wide North Atlantic warming. We also find evidence that reduced shipping emissions could have played a localized role, with anomalous clear skies contributing enhanced warming anomalies along a band of latitudes coinciding with the region's main shipping lanes (Extended Data Fig. 9). Given that ERA5 does not include interannual variability in shipping emissions, we further tested these results by recalculating the MLT budget with an additional +1 W m −2 anomaly in incoming solar radiation applied everywhere over the North Atlantic ( Methods). This shortwave radiation anomaly is approximately double the basin-average estimate for the impact of reduced shipping emissions over the North Atlantic in ref. 31, which is at the high end of available estimates. In all analyses shown, both model and observations, our results remain robust to this addition of 1 W m −2 solar radiation, with minimal changes to the results shown (see, for example, Extended Data Fig. 11).

An analysis of the past few decades of ocean and atmosphere measurements reveals no notable trend in surface wind speed over the North Atlantic Ocean, but there is a marked trend towards shallower MLDs across all seasons (Fig. 3e and, for summer, Extended Data Figs. 7a, 8a), as well as a notable trend towards increased incoming solar radiation in summer (Extended Data Fig. 7c). In the absence of surface wind trends, the mixed layer shoaling trend must be driven by a combination of stronger summer heating and surface freshwater input, both of which act to enhance the stratification of the upper ocean. This is analysed in Extended Data Fig. 8b,c, which shows the 1981-2023 multidecadal trends in North Atlantic SST and sea surface salinity. Also shown in Extended Data Fig. 8d-f are trends in summertime sea surface density, alongside the estimated density trend owing to surface temperature and salinity effects alone. This analysis reveals that the shoaling North Atlantic mixed layer trend over the past four decades is primarily driven by surface ocean warming, with a smaller contribution from surface freshening in the tropics and subpolar latitudes. The multidecadal surface ocean warming is primarily because of long-term anthropogenic warming, with a possible further contribution from a trend in incoming solar radiation (estimated to be +0.58 W m −2 per decade from ERA5 data; Extended Data Fig. 7c), which is consistent with reduced shipping emissions and variations in the solar cycle, as noted in previous work35. Overall, warming and freshening has led to much shallower MLDs in the past decade compared with the late twentieth century. A trend towards shallower mixed layers preconditions the Atlantic for an increase in the likelihood of severe summertime marine heatwaves of the type observed in 2023. Similar preconditioning of severe marine heatwaves has also been noted for the North Pacific Ocean36,37.

Summary and conclusions

To summarize, the anomalous warming of the surface mixed layer in the North Atlantic Ocean during summer 2023 was unprecedented in both spatial scale and magnitude over the observational record, forming a near-basin-wide anomaly that has persisted over much of the basin until today. We identify the dominant drivers of this extreme North Atlantic marine heatwave to be low wind speeds and anomalously shallow mixed layers, alongside a regional contribution from anomalous clear skies and increased surface ocean heat flux. Moreover, our study highlights the importance of a shoaling mixed layer in the development of extreme summertime marine heatwaves, because during seasons of climatological warming, a shallow mixed layer can lead to rapid surface warming without the need for anomalous radiation or turbulent heat fluxes into the ocean.

The record shallow mixed layers seen in 2023 seem to have been bolstered by a long-term mixed layer shoaling trend observed in the North Atlantic, one that is projected to continue into the future. The likelihood of similar events occurring is thus expected to increase in the coming years and beyond. With the prevailing atmospheric circulation moving oceanic air masses towards Europe and other regions, alongside the proximity of the summertime heating to Greenland and the source waters for the Atlantic meridional overturning circulation, this has potential major implications for future climate at regional to global scales.

Methods

Observational and reanalysis data

The atmospheric and air-sea flux fields analysed in this study are taken from the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis Version 5 (ERA5)38, using daily mean fields derived from hourly data and monthly averaged fields from 1981 to 2023 over a 1/4° horizontal resolution grid. Variables analysed from ERA5 include surface wind speed (m s −1) and surface wind vectors, surface air-sea heat fluxes (W m −2), mean sea-level pressure (hPa) and cloud cover fraction. SST (°C) is also taken from ERA5. The net air-sea heat flux is the sum of incoming shortwave radiation less outgoing latent, sensible and longwave radiative heat fluxes.

The surface net shortwave (solar) radiation corresponds to the amount of solar radiation that reaches the surface of the Earth (both direct and diffuse) minus the amount reflected by the Earth's surface (which is governed by the albedo). In the ERA5 reanalysis, only climatological aerosol effects and aerosol changes due to large volcanic eruptions are incorporated into the estimate of the net surface shortwave (solar) radiation. In particular, the incoming solar radiation is partly reflected back to space because of both clouds as well as particles in the atmosphere (aerosols), but without interannual variability in aerosol effects aside from volcanic eruptions. The remainder is incident on the Earth's surface, for which some of it is reflected owing to surface albedo effects. ERA5 assimilates cloud liquid water from a variety of satellites, as detailed in the ERA5 online documentation, formulating cloud fraction and cloud albedo as surface and single-level parameters of the reanalysis. To test the sensitivity of our results to aerosol effects from reduced shipping emissions, we further analysed the observed and modelled MLT budgets by adding 1 W m −2 to the solar radiation terms for all months in 2023, and also to just the summer months May-August when solar radiation effects are at their maximum. The added heat flux of +1 W m −2 is approximately double the basin-average estimate for the impact of reduced shipping emissions over the North Atlantic of 0.56 W m −2 in ref. 31, which is at the high end of available estimates. In all cases our results remain robust to this addition of 1 W m −2 solar radiation, with negligible changes to the results shown (Extended Data Fig. 11).

Subsurface ocean temperature and MLDs are obtained from an observation-based dataset; the Institute of Atmospheric Physics (IAP) hydrographic data39,40,41 version 3 available from 1981 to 2023 with 1° horizontal resolution (hereafter referred to as 'IAP data'). The main latitude band of interest spans the North Atlantic from the equator to 60° N, which mostly avoids regions of low data coverage, such as the high-latitude regions, particularly ice-covered areas. Sparse coverage by Argo floats is, however, a problem in marginal seas, although the gridded IAP climatology merges both Argo and other historical hydrographic observations, including XBTs. Nonetheless, reliable reconstruction of interior ocean temperature and MLD is only available at monthly mean resolution. The Gibbs SeaWater (GSW) Oceanographic Toolbox42 from the TEOS-10 software43 is applied to convert the IAP in situ temperature to conservative temperature44. Static stability of the water column on timescales of months is achieved by applying vertical stabilization software45. The surface-referenced potential temperature, θ, and potential density, ρ, are then calculated using functions from the GSW Oceanographic Toolbox.

Ocean MLD is calculated as the depth at which the monthly averaged potential density in the water column first exceeds the density at 10-m depth by 0.125 kg m −3, following previous work46. The MLD anomalies and the related MLT budget analyses were repeated using a density threshold of 0.03 kg m −3 and the results presented here are robust to this choice. MLD anomalies were also re-evaluated using a reference depth of 5 m instead of 10 m and robust patterns were obtained. The separate contributions of T and S to the surface density trends were also calculated (Extended Data Fig. 8). This was done by combining the monthly climatological salinity field (averaged during 1981-2010) with the time-varying temperature fields to derive the temperature contribution. When estimating the salinity effects on density trends, the opposite was done, namely, using the climatological mean temperature fields alongside the time-varying salinity fields.

The robustness of the estimated 2023 anomalies in MLD derived from IAPv3 data was evaluated by examining the corresponding MLD anomalies in the IAPv4, ORAS5 and ensemble mean of EN4.2.2 datasets (EN4-ESM). Overall consistent patterns of record shallow MLD anomalies were obtained during 2023 in all four datasets (Extended Data Fig. 10). However, there are variations in the long-term multidecadal trends in MLD and upper ocean temperature gradients estimated by the different products (Extended Data Fig. 10), consistent with previous findings for the North Pacific36. The differences in long-term trends are in part the result of data sparsity before the Argo period, although variations can also be seen in the more recent record. Note also that the EN reanalysis is less reliable for long-term trend estimates47, as missing values relax to climatology in the absence of any observations. Nonetheless, in all ocean reanalyses considered, 2023 sees a sudden anomalous shoaling of the mixed layer compared with previous years.

Ocean model simulations

Two ocean model simulations forced by different observation-based atmospheric reanalysis fields, namely, ERA5 and JRA55-do, were integrated to evaluate the driving mechanisms of the North Atlantic peak warming during 2023. The two model simulations both capture the temporal evolution of the onset of surface layer warming over the North Atlantic during 2023, particularly the ERA5-forced simulation (Fig. 1a). The model configurations are taken from the Australian Community Climate and Earth System Simulator Ocean Model Version 2 (ACCESS-OM2) with the configurations run at a nominal 0.25° horizontal resolution with 50 vertical levels (surface grid cell thickness of 2.3 m). ACCESS-OM2 is a global ocean-sea-ice model driven by a prescribed atmosphere; the version used here has been described previously48, with improvements described by follow-up work49. The ocean model component is the Modular Ocean Model (MOM) version 5.1 (ref. 50), coupled to the Los Alamos sea ice model version 5.1.2 (ref. 51). Vertical mixing in the boundary layer is parameterized using the K profile parameterization (KPP52). Further model details can be found in previously published work48,49.

The forcing of the two ocean model simulations is as follows. In the main run analysed here, referred to as the ERA5 simulation, the model is forced by ERA5 atmospheric reanalysis fields38. In the second simulation, referred to as the JRA55 run, the Japanese 55-year Reanalysis (JRA55-do) dataset for forcing ocean-sea-ice models is used. In the JRA55 run, after spinning up over six cycles forced by the 1958-2018 JRA55-do v1.4 fields (following the OMIP-5 spinup protocol53), the sixth cycle is extended using JRA55-do v1.5.0 for 2019 and the delayed-mode JRA55-do v1.5.0.1 to the end of 2023 (ref. 54). The ERA5 run is initialized at the end of 1957 and then run over 1958-2023 using ERA5 atmospheric forcing, with runoff taken from JRA55-do (as for the JRA55 run). Both model runs were initialized using World Ocean Atlas 2013 v2 temperature and salinity fields55,56.

The model data analysed here include SST and surface heat fluxes from both the ERA5 and JRA55 simulations and, for the ERA5 run, all variables required to reconstruct a surface MLT budget (detailed below) both during 2023 and also during all years of the model simulation from 1981 onwards, to construct the baseline 1981-2010 climatological mean MLT budget from which we evaluate the 2023 anomaly fields. The North Atlantic SST evolution of the two model runs is, overall, consistent with observations (Fig. 1a), as is the pattern of MLD shoaling across the North Atlantic during 2023 (Extended Data Fig. 6). The magnitude of air-sea surface heat flux anomalies during 2023 is also consistent with observations, as revealed in the breakdown of the anomalous net surface heat flux contributions to the MLT budget during May-August (compare Figs. 4a and 5a). The geographic pattern of net surface-heat-flux-driven MLT warming also compares well between both model runs and observations.

Surface layer temperature budget

A budget for the upper ocean MLT can be written as

$$\frac{\partial {\theta }_{{\rm{h}}}}{\partial t}=\frac{{Q}_{{\rm{net}}}-{Q}_{{\rm{h}}}}{{\rho }_{0}{c}_{{\rm{p}}}h}+{\rm{advection}}+{\rm{entrainment}}+{\rm{mixing}}$$

in which θ h is the MLT, t is time, Q net is the net surface air-sea heat flux (W m −2), Q h is the heat flux corresponding to shortwave radiation penetration across the base of the mixed layer (also in W m −2), ρ ₀ is seawater density (taken to be 1,027 kg m −3), c p = 3,992 J K −1 kg −1 is the heat capacity of seawater, h is the MLD (m), advection represents net heating owing to three-dimensional ocean advection, entrainment represents the heat flux associated with mixed layer shoaling or deepening and the mixing term includes the net heat flux owing to parameterized subgrid-scale processes such as vertical mixing and eddy-induced mixing. The entrainment term can be written as:

$$-\frac{1}{h}\frac{\partial h}{\partial t}({\theta }_{{\rm{h}}}-{\theta }_{{\rm{ent}}}),$$

representing entrainment associated with mixed layer shoaling or deepening, with θ ent the temperature of detrained/entrained water and θ h the MLT.

The shortwave penetration across the base of the mixed layer ( Q h) in the model is computed online and output as a heat budget diagnostic by MOM5, in which shortwave radiation is distributed into the ocean interior as a function of depth57, modulated by the seasonal climatological chlorophyll distribution58. The penetration of shortwave radiation across the base of the mixed layer for the observationally based estimate is taken as Q h =  Q SW. F( z), in which Q SW is the shortwave radiation across the air-sea interface from the ERA5 reanalysis and F( z) is the exponential decay function59,

$$F(z)=R{{\rm{e}}}^{-\frac{z}{{h}_{1}}}+(1-R){{\rm{e}}}^{-\frac{z}{{h}_{2}}}$$

where z is depth (positive downwards), R = 0.58, h ₁ = 0.35 m and h ₂  = 23 m.

The two ocean model simulations give, overall, robust results in terms of the magnitude of the anomalous surface heat flux contributions to the MLT tendency terms (figure not shown), including the breakdown into shortwave, longwave, sensible and latent heat flux terms. The focus of our more detailed MLT budget analysis is the ERA5 run, which was integrated with all required terms saved to quantify monthly variations in the MLT balance, including three-dimensional ocean advection and mixing, as described below. The temperature budget of the ERA5 model can also be compared with estimates using the observationally based ERA5 reanalysis combined with IAP estimates of surface ocean temperature and mixed layer fields. However, insufficient observational data are available to constrain the other surface MLT budget terms, such as ocean advection and mixing, as well as vertical entrainment. We can nonetheless compare the surface air-sea heat flux contributions across the model and observed reanalysis fields.

All terms in the model MLT budget, including all components of ocean advection, mixing and entrainment, can be diagnosed by integrating the fully closed cell-by-cell model heat budget50,60,61 over the surface mixed layer (defined here using the same definition as the observed MLD, described above) and dividing by the surface MLD. Here this integration is performed using monthly averaged heat budget diagnostics and the monthly averaged MLD. The entrainment term, the only term not explicitly included in the three-dimensional model heat budget, is computed by residual as the difference between the tendency of the MLT (computed by taking the difference of snapshots of the temperature and the MLD at the beginning and end of each month) and the total mixed layer heat content tendency (that is, the sum of all point-by-point heat budget processes, divided by ρ ₀ c p h). Such a calculation produces a closed budget but neglects correlations between submonthly variations in the MLD and cell-by-cell model heat budget terms. However, a comparison performed in 2023 between these monthly averaged budget terms and similar terms obtained using daily averages (only available for 2023) showed only small differences (order less than 5%; figure not shown).

The MLT budget analysis for observations (Fig. 5) is derived by comparing the estimated mixed layer heat storage rate to the heating and cooling driven by surface heat fluxes alone (less shortwave penetration at the base of the mixed layer), with the residual implicitly including all ocean advection, entrainment and mixing terms, as well as any errors owing to incomplete data coverage in space and time, uncertainty in estimating MLDs and temperatures and uncertainty in the ERA5 net air-sea heat fluxes (both in 2023 and in the baseline period 1981-2010). As for the model simulations, the observational budget also neglects submonthly correlations between the surface heat flux and MLD variations, although analysis of the model budget at daily and monthly timescales suggests that this term is small. The MLT tendency, ∂ θ h/∂ t, is calculated from monthly observations as a centred second-order difference of monthly mean MLT. With only monthly MLD values available from observations, this results in substantial smoothing of the MLT warming signal compared with the daily resolved model MLT budget.

The pattern of residual terms seen in the observed calculation reveals features that include unresolved temperature changes due to ocean circulation effects both laterally, such as in the Gulf Stream, and also vertically, because of entrainment and vertical mixing at the base of the mixed layer. By contrast, the MLT budget of the model explicitly resolves the contributions from ocean circulation and mixing, and so all terms can be shown.

The shortwave radiation anomalies in the MLT budget are further diagnosed by recalculating these anomalies during 2023 but separately considering the effects on MLT of 2023 anomalies in MLD, surface incoming shortwave radiation and radiation through the base of the mixed layer. This calculation simply recomputes the 2023 MLT budget holding all other variables at their climatological mean, then separately including the 2023 anomalies in MLD (MLD′), surface shortwave heat flux ( Q SW′) and anomalies owing to the radiative flux across the base of the mixed layer ( Q SW,H′). The resulting values are shown from the ERA5-forced model run and observations in Figs. 4a and 5a and Extended Data Fig. 9, respectively. This decomposition indicates the sign and magnitude of the shortwave radiation component of the MLT budget anomalies assuming that only one of these three factors (MLD′, Q SW′ and Q SW,H′) varied with its 2023 values. For example, the MLD′ values indicate the size of the 2023 shortwave radiation term assuming that the incoming shortwave radiation, and the radiation through the base of the mixed layer, followed the climatological mean. The Q SW′ term conversely takes MLD and Q SW,H to follow the climatological mean, with Q SW varying with its 2023 values. Last, Q SW,H′ assumes that Q SW and MLD follow the climatological mean, with only the radiative flux through the base of the mixed layer evolving with its 2023 values. This approach is a simple way to evaluate what factors were the most important in generating the summertime warming in the North Atlantic during 2023, although the contributions are not additive to unity by definition.

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Acknowledgements

M.H.E., Z.L., M.F.H. and A.S.G. are supported by the Australian Research Council (ARC) Centre for Excellence in Antarctic Science (ARC grant SR200100008) and A.E.K. by ARC grant LP200100406. A.S.G. is supported by an ARC Future Fellowship (FT220100475). We thank the European Centre for Medium-Range Weather Forecasts (ECMWF) for making the ERA5 reanalysis data freely available online. The availability of ERA5 data at the National Computational Infrastructure has been made possible through ARC LIEF grant LE200100040. We thank the Consortium for Ocean-Sea Ice Modelling in Australia (COSIMA; http://www.cosima.org.au) for making the ACCESS-OM2 suite of models available at https://github.com/COSIMA/access-om2. Model runs were undertaken with the assistance of resources from the National Computational Infrastructure (NCI), which is supported by the Australian Government. The gridded Institute of Atmospheric Physics temperature and salinity data were obtained from http://www.ocean.iap.ac.cn/. The subsurface temperature and salinity fields from Argo floats were collected and made freely available by the international Argo Program and the national programmes that contribute to it ( http://www.argo.ucsd.edu, https://www.ocean-ops.org/board?t=argo). The Argo Program is part of the Global Ocean Observing System.

Funding

Open access funding provided through UNSW Library.

Author information

Authors and Affiliations

1. Centre for Marine Science and Innovation (CMSI) and ARC Australian Centre for Excellence in Antarctic Science, University of New South Wales, Sydney, New South Wales, Australia

Matthew H. England, Zhi Li & Maurice F. Huguenin

2. Research School of Earth Sciences and ARC Centre of Excellence for Climate Extremes, Australian National University, Canberra, Australian Capital Territory, Australia

Andrew E. Kiss

3. Climate Change Research Centre (CCRC) and ARC Australian Centre for Excellence in Antarctic Science, University of New South Wales, Sydney, New South Wales, Australia

Alex Sen Gupta

4. Australian Bureau of Meteorology, Sydney, New South Wales, Australia

Ryan M. Holmes

5. Potsdam Institute for Climate Impact Research, Potsdam, Germany

Stefan Rahmstorf

Contributions

M.H.E. and S.R. conceived the study. R.M.H. and A.E.K. ran the numerical ocean model experiments. M.F.H. and R.M.H. processed the model-simulated heat budget terms. Z.L. processed and analysed all of the observational analyses and heat budget calculations and produced all of the diagrams, except for the schematic in Fig. 5. M.H.E. led the design of the analyses and figures and wrote the first draft of the paper. All authors contributed to refinement of the paper and interpretation of the results.

Corresponding author

Correspondence to Matthew H. England.

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Nature thanks Marlos Goes and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

a- d, The mean sea-level pressure (hPa) is shown as contours and anomalies are shaded and calculated relative to the 1981-2010 mean. Mean and anomalous sea-level pressure fields are calculated from hourly ERA5 data.

Values are calculated between the equator and 60° N, with years indicated by colour shaded lines, from dark blues (earliest years) to pale blues (most recent years) and 2023 indicated in bold red. Units are m s −1. Area averages are calculated separately east and west of 40° W. a, Eastern North Atlantic. b, Western North Atlantic. Wind speeds shown are calculated from hourly ERA5 data.

a- d, Cloud cover anomalies are shaded and calculated as a fraction (values ranging from 0 to 1) relative to the 1981-2010 mean. Low-medium cloud cover corresponds to the total cloud cover from the surface up to a height of approximately 450 hPa. The +1 °C and −1 °C SST anomaly contours from Fig. 2 are overlaid in red and blue, respectively. To avoid any ambiguity, the regions of anomalous warming are indicated by the small red tick marks added around the +1 °C anomaly contour. Cloud cover anomalies are calculated from hourly ERA5 data.

a- l, Shown are the monthly anomalies in the incoming air-sea net surface heat flux Q net (left column), the incoming shortwave radiation (middle column) and the latent heat flux (right column). Heat flux anomalies (W m −2) are shaded and calculated relative to the 1981-2010 mean. Positive (red) values indicate anomalous heat flux into the ocean, negative values are anomalous ocean heating of the atmosphere. The +1 °C and −1 °C SST anomaly contours from Fig. 2 are overlaid in red and blue, respectively. To avoid ambiguity, the regions of anomalous warming are indicated by the small red tick marks added around the +1 °C anomaly contour. All surface heat flux anomalies are calculated from hourly ERA5 data.

a- d, Salinity anomalies (shaded) are calculated relative to the 1981-2010 mean using monthly IAPv3 data ( Methods). e, Time series of North Atlantic area-averaged salinity anomalies (equator to 60° N), with years indicated by colour shaded lines, from dark blues (earliest years) to pale blues (most recent years) and 2023 indicated in bold red.

The model data are taken from the run forced by ERA5 atmospheric variables. a- d, MLD anomalies (shaded) normalized by one standard deviation (SD) for each month and location, and shown as the number of standard deviations from the 1981-2010 mean. The MLD is calculated using a density threshold criterion of 0.125 kg m −3, relative to surface density. e, Time series of North Atlantic area-averaged model MLD anomalies (equator to 60° N), with years indicated by colour shaded lines, from dark blues (earliest years) to pale blues (most recent years) and 2023 indicated in bold red. For comparison, the 2023 MLD anomalies in the JRA55-forced model run are also included in panel e.

Time series of summertime North Atlantic basin-averaged MLD (m) ( a), upper ocean temperature stratification (°C m −1) ( b), and incoming solar radiation anomalies (W m −2) ( c). The ocean time series ( a, b) are derived from IAPv3 and the solar radiation anomalies ( c) from ERA5 ( Methods). The upper ocean temperature stratification is calculated between the surface and 50-m depth. All basin-averaged trend lines shown are significant at the 95% confidence level. In panel a, the shoaling trend in MLD averaged over June-August is −0.58 m per decade during 1980-2023. In panels a and b, trend lines are shown excluding and including the period 2020-2022 (after the International Maritime Organization 2020 agreement27,28). Time series in panels a and b are shown for the whole North Atlantic as well as separated into the western and eastern sectors (separated at 40° W).

Trends are calculated over the period 1981-2023 for the summer June-August season. a- c, June-August trends in MLD, SST and sea surface salinity (SSS). Units are m, °C and g kg −1 per year, respectively. MLD is calculated as the depth at which the monthly averaged potential density in the water column first exceeds the density at 10-m depth by 0.125 kg m −3. d- f, Trends in June-August surface density and the estimated density trend due to surface temperature and salinity effects alone. Units are kg m −3 per year. g- j, Anomalies in temperature profiles averaged over the North Atlantic (equator to 60° N) during May-August 1981-2023, calculated relative to the 1981-2010 climatological mean, with years indicated by colour shaded lines, from dark blues (earliest years) to pale blues (most recent years) and 2023 indicated in bold red. Data for SST are taken from ERA5, whereas surface salinity, density, MLD and subsurface T- S data are taken from IAPv3 ( Methods).

The analysis is shown for the peak warming months of June 2023 ( a) and July 2023 ( b), based on observations and reanalysis data. Values are based on the difference between the MLT budget contributions from (1) the net shortwave radiation term ( Q SW) estimated by holding the MLD value at its climatological mean (with Q SW varying) and (2) the mixed layer shoaling term estimated by holding incoming shortwave radiation at its climatological mean (with MLD varying). In this way, red shading denotes areas in which the solar radiation effect dominates the MLT anomalies and blue shading denotes regions in which MLD shoaling dominates the MLT anomalies. The budget terms are calculated using ERA5 air-sea heat fluxes combined with MLD and MLT derived from IAPv3 ( Methods). The analysis presented here does not include the effects of interannual variability in shipping emissions. See Methods and Extended Data Fig. 11 for further details estimating shipping emission effects.

a, Time series of summertime (June-August) basin-averaged North Atlantic MLD (m) anomalies during 1980-2023. b, Same as a but showing basin-averaged d T/d z (°C m −1). c- f, Summertime anomalies in MLD (m) estimated during 2023 from the IAPv3, IAPv4, ORAS5 and EN4-ESM reanalysis products. Linear trends are indicated by the dashed lines in panels a and b.

(a) MLT budget as per Fig. 5a of the main paper, included here for comparison, using ERA5 estimates for the surface heat flux terms. Note that the ERA5 reanalysis does not include the effects of interannual variability in shipping emissions. (b) Same as panel (a), but showing the MLT budget terms recalculated imposing an additional 1 W m −2 anomaly in the incoming solar radiation term Q SW during 2023, to examine the potential impact of reduced shipping emissions on the observed MLT budget. The additional 1 W m −2 is applied over the whole North Atlantic in 2023. For reference, estimates of the impact of reduced shipping emissions typically vary between 0.1 - 0.3 W m −2, with highest estimates for the basin-averaged North Atlantic corresponding to an increase in Q SW of 0.56 W m −2 during 2023 (ref. 31). In this way, panel (b) can be interpreted as an upper bound on the effects of shipping emission reductions in the MLT budget calculation. The methods and bar chart terms shown match the terms shown in Fig. 5a.

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England, M.H., Li, Z., Huguenin, M.F. et al. Drivers of the extreme North Atlantic marine heatwave during 2023. Nature 642, 636-643 (2025). https://doi.org/10.1038/s41586-025-08903-5
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Drivers of the extreme North Atlantic marine heatwave during 2023 - Nature

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North Atlantic Ocean circulation and temperature patterns profoundly influence global and regional climate across all timescales, from synoptic1 to seasonal2-4, decadal5, multidecadal6,7 and beyond8,9. During 2023, an extreme and near-basin-scale marine heatwave developed during Northern Hemisphere summer, peaking in July.

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기후변화 환경교육 고등학교 영어과 교육자료

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기후변화 환경교육 고등학교 영어과 교육자료

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2023. 기후변화환경교육 고등학교용 영어과 교과연계 학습자료.pdf