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The threat of invasive species - Jennifer Klos

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How much do you know????

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Climate Change: Vital Signs of the Planet

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NASA Global Climate Change and Global Warming: Quizzes

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How much do you know about carbon, ice, energy and more? Take our quizzes to find out.

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On climate change

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What is the Paris Agreement on Climate Change?

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In 2015 the EU and 179 countries spent two weeks in Paris hammering out an agreement to keep global temperature increases below 2C. Two years on, it matters more than ever.

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Climate Change: Vital Signs of the Planet

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The rate of change since the mid-20th century is unprecedented over millennia.

Earth's climate has changed throughout history. Just in the last 800,000 years, there have been eight cycles of ice ages and warmer periods, with the end of the last ice age about 11,700 years ago marking the beginning of the modern climate era - and of human civilization. Most of these climate changes are attributed to very small variations in Earth's orbit that change the amount of solar energy our planet receives.

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.) Find out more about ice cores (external site).

The current warming trend is different because it is clearly the result of human activities since the mid-1800s, and is proceeding at a rate not seen over many recent millennia. It is undeniable that human activities have produced the atmospheric gases that have trapped more of the Sun's energy in the Earth system. This extra energy has warmed the atmosphere, ocean, and land, and widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred.

Do scientists agree on climate change?

Yes, the vast majority of actively publishing climate scientists - 97 percent - agree that humans are causing global warming and climate change.

detailed answer

Earth-orbiting satellites and new technologies have helped scientists see the big picture, collecting many different types of information about our planet and its climate all over the world. These data, collected over many years, reveal the signs and patterns of a changing climate.

Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th century. Many of the science instruments NASA uses to study our climate focus on how these gases affect the movement of infrared radiation through the atmosphere. From the measured impacts of increases in these gases, there is no question that increased greenhouse gas levels warm Earth in response.

"Scientific evidence for warming of the climate system is unequivocal."

- Intergovernmental Panel on Climate Change

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth's climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. Carbon dioxide from human activities is increasing about 250 times faster than it did from natural sources after the last Ice Age.

References

References
Header image shows clouds imitating mountains as the sun sets after midnight as seen from Denali's backcountry Unit 13 on June 14, 2019. Credit: NPS/Emily Mesner

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Climate Change Evidence: How Do We Know?

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Vital Signs of the Planet: Global Climate Change and Global Warming. How do we know it's happening? Here's the evidence.

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Can they survive?

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CLIMATE CHANGE

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Climate Change 101 with Bill Nye | National Geographic

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In 2002, the Nobel-winning scientist Paul Crutzen was at a meeting where the chairman kept using the term "Holocene" to describe the present day. This is, technically, correct: the Holocene began at the end of the last ice age. But Crutzen, who had won his Nobel for his work on the effects of ozone-depleting compounds (and so, in being instrumental in shrinking the holes in the ozone layer, could be said to have saved the planet), blurted out that we should actually be calling the present day the Anthropocene: the epoch influenced by humanity. When word of this proposal reached the Geological Society of London, and specifically its stratigraphy committee - the people who decide such matters - they thought about it for a year, and decided: yes, Anthropocene sounds about right.

We really are that influential - and destructively so. And yet if all civilisation were to end now, then 100m years hence, everything we have built would be compressed, in the geological record, to a layer of sediment "not much thicker than a cigarette paper", as Elizabeth Kolbert puts it.

There is something almost literary about the process of understanding deep history. There is, above all, the business of being able to read correctly what the different layers of rock and sediment tell us about life on Earth. There is the business of being able to read the signs around us of the living record, and to learn to think in the long, rather than short term. It is instructive to discover that we can date the concept of extinction to the year: 1795, when Georges Cuvier examined some recently exhumed mastodon bones and realised that the concept of a divinely ordered animal kingdom was invalid, and that species could be lost for ever. (Kolbert notes that it might not be a coincidence that the notion of extinction arose in revolutionary France.)

And then there is the business of coming up with words to describe these new concepts. Some can be traced to individuals rather than committees. Ninteenth-century English polymath William Whewell, for instance, who has given the language such words as "anode", "cathode", "ion", and, most remarkably, "scientist", came up with "catastrophist" to describe someone who believes that evolution is punctuated and determined by periodic upheavals in the environment. The term may not be used much any more, but, given that the current view of evolutionary pressure is "long periods of boredom punctuated by panic", the idea behind it is not obsolete.

It would seem now, though, that the panic is entirely down to us. There are grounds to believe that the first mass extinction of life on Earth ( the end-Ordovician, to be precise) was caused by newly emergent plant life; and the end-Cretaceous, as I'm sure you all know, was caused by a meteor slamming into what is now the Yucatán peninsula. Kolbert describes this very well and vividly, and also reminds us that every animal larger than a cat was wiped out.

Now, though, we are at the point where we are the meteor. Our impact on life on Earth is not as spectacular, nor as instantaneous; but in geological terms it might as well be. As the planet warms up, and carbon dioxide acidifies the oceans, all bets are off - except the ones hinging on mass extinctions. As one scientist quoted here puts it: "Look around you. Kill half of what you see. Or if you're feeling generous, just kill about a quarter of what you see."

Kolbert's book is not, thankfully, as depressing as you might think. She has a good grip on her subject and uses a light touch when it is most needed. The main thing is that what she says is necessary to know. I wonder how a climate change denier would take this book; the science of climate change is, here, entirely pervasive, entirely beyond doubt, as just about everyone who has properly studied the subject would be able to tell you. Meanwhile, mourn the great auk, the moa, the broad-faced potoroo ... and an uncountable number of other species.

* To order The Sixth Extinction for £7.19 go to bookshop.theguardian.com or call 0330 333 6846.
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The Sixth Extinction by Elizabeth Kolbert review - 'kill half of what you see'

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In 2002, the Nobel-winning scientist Paul Crutzen was at a meeting where the chairman kept using the term "Holocene" to describe the present day. This is, technically, correct: the Holocene began at the end of the last ice age.

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By VP Al Gore

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In “The Sixth Extinction,” Elizabeth Kolbert combines scientific analysis and personal narratives to convey the history of earth’s previous mass extinctions and to consider what may come next.