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What Can Trees Tell Us About Climate Change

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What Can Trees Tell Us About Climate Change

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NASA

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Quite a lot, actually!

But to understand what the trees tell us, we first have to understand the difference between weather and climate.

is a specific event-like a rain storm or hot day-that happens over a short period of time. Weather can be tracked within hours or days. is the average weather conditions in a place over a long period of time (30 years or more).

Scientists at the National Weather Service have been keeping track of weather in the United States since 1891. But trees can keep a much longer record of Earth's climate. In fact, trees can live for hundreds-and sometimes even thousands-of years!

One way that scientists use trees to learn about past climate is by studying a tree's rings. If you've ever seen a tree stump, you probably noticed that the top of the stump had a series of rings. It looks a bit like a bullseye.

These rings can tell us how old the tree is, and what the weather was like during each year of the tree's life. The light-colored rings represent wood that grew in the spring and early summer, while the dark rings represent wood that grew in the late summer and fall. One light ring plus one dark ring equals one year of the tree's life.

Because trees are sensitive to local climate conditions, such as rain and temperature, they give scientists some information about that area's local climate in the past. For example, tree rings usually grow wider in warm, wet years and they are thinner in years when it is cold and dry. If the tree has experienced stressful conditions, such as a drought, the tree might hardly grow at all in those years.

Scientists can compare modern trees with local measurements of temperature and precipitation from the nearest weather station. However, very old trees can offer clues about what the climate was like long before measurements were recorded.

In most places, daily weather records have only been kept for the past 100 to 150 years. So, to learn about the climate hundreds to thousands of years ago, scientists need to use other sources, such as trees, corals, and ice cores (layers of ice drilled out of a glacier).

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What Can Trees Tell Us About Climate Change?

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Tree rings can provide information about past climate!

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Ted-Ed | 2020

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What happens if you cut down all of a city's trees? - Stefan Al

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Who Needs Dirt?: Crash Course Kids #27.1

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Margarita Engle | 2017
Amazon

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Tree planting 'has mind-blowing potential' to tackle climate crisis

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Tree planting 'has mind-blowing potential' to tackle climate crisis

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Damian Carrington | The Guardian | 2019

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Planting billions of trees across the world is one of the biggest and cheapest ways of taking CO2 out of the atmosphere to tackle the climate crisis, according to scientists, who have made the first calculation of how many more trees could be planted without encroaching on crop land or urban areas.

As trees grow, they absorb and store the carbon dioxide emissions that are driving global heating. New research estimates that a worldwide planting programme could remove just under one-third of all the emissions from human activities that remain in the atmosphere today, a figure the scientists describe as "mind-blowing".

The analysis found there are 1.7bn hectares of treeless land on which 1.2tn native tree saplings would naturally grow. That area is about 11% of all land and equivalent to the size of the US and China combined. Tropical areas could have 100% tree cover, while others would be more sparsely covered, meaning that on average about half the area would be under tree canopy.

The scientists specifically excluded all fields used to grow crops and urban areas from their analysis. But they did include grazing land, on which the researchers say a few trees can also benefit sheep and cattle.

"This new quantitative evaluation shows [forest] restoration isn't just one of our climate change solutions, it is overwhelmingly the top one," said Prof Tom Crowther at the Swiss university ETH Zürich, who led the research. "What blows my mind is the scale. I thought restoration would be in the top 10, but it is overwhelmingly more powerful than all of the other climate change solutions proposed."

Crowther emphasised that it remains vital to reverse the current trends of rising greenhouse gas emissions from fossil fuel burning and forest destruction, and bring them down to zero. He said this is needed to stop the climate crisis becoming even worse and because the forest restoration envisaged would take 50-100 years to have its full effect of removing 200bn tonnes of carbon.

But tree planting is "a climate change solution that doesn't require President Trump to immediately start believing in climate change, or scientists to come up with technological solutions to draw carbon dioxide out of the atmosphere", Crowther said. "It is available now, it is the cheapest one possible and every one of us can get involved." Individuals could make a tangible impact by growing trees themselves, donating to forest restoration organisations and avoiding irresponsible companies, he added.

Other scientists agree that carbon will need to be removed from the atmosphere to avoid catastrophic climate impacts and have warned that technological solutions will not work on the vast scale needed.

Jean-François Bastin, also at ETH Zürich, said action was urgently required: "Governments must now factor [tree restoration] into their national strategies."

There are about 3tn trees on the planet and they play a significant role in producing the oxygen we all breathe. But twice as many existed before the start of human civilisation.

Today, 10bn more trees are cut down than are planted every year. This destruction is a significant contributor to the carbon dioxide emissions that are driving the climate crisis. rees draw carbon dioxide back out of the atmosphere as they grow, and planting trees will need to play an important part in ending the climate emergency.

Forests are also a vital and rich habitat for wildlife. Earth is at the start of a sixth mass extinction event of species and the razing of forests and other ecosystems is the biggest contributor to the losses. Tropical rainforests are especially important, hosting 50% of known terrestrial species on only 6% of the world's land. Trees are also important in controlling regional rainfall, as they evaporate water from their leaves.

In urban areas, the shade from trees has been shown to both cool city streets and reduce levels of air pollution. They can also boost people's wellbeing as part of green spaces, with research showing a two-hour "dose" of nature a week significantly improving health.

Thank you for your feedback.

Christiana Figueres, former UN climate chief and founder of the Global Optimism group, said: "Finally we have an authoritative assessment of how much land we can and should cover with trees without impinging on food production or living areas. This is hugely important blueprint for governments and private sector."

René Castro, assistant-director general at the UN Food and Agriculture Organisation, said: "We now have definitive evidence of the potential land area for re-growing forests, where they could exist and how much carbon they could store."

The study, published in the journal Science, determines the potential for tree planting but does not address how a global tree planting programme would be paid for and delivered.

Crowther said: "The most effective projects are doing restoration for 30 US cents a tree. That means we could restore the 1tn trees for $300bn [£240bn], though obviously that means immense efficiency and effectiveness. But it is by far the cheapest solution that has ever been proposed." He said financial incentives to land owners for tree planting are the only way he sees it happening, but he thinks $300bn would be within reach of a coalition of billionaire philanthropists and the public.

Effective tree-planting could take place across the world, Crowther said: "The potential is literally everywhere - the entire globe. In terms of carbon capture, you get by far your biggest bang for your buck in the tropics [where canopy cover is 100%] but every one of us can get involved." The world's six biggest nations, Russia, Canada, China, the US, Brazil and Australia, contain half the potential restoration sites.

Tree planting initiatives already exist, including the Bonn Challenge, backed by 48 nations, aimed at restoring 350m hectares of forest by 2030. But the study shows that many of these countries have committed to restore less than half the area that could support new forests. "This is a new opportunity for those countries to get it right," said Crowther. "Personally, Brazil would be my dream hotspot to get it right - that would be spectacular."

The research is based on the measurement of the tree cover by hundreds of people in 80,000 high-resolution satellite images from Google Earth. Artificial intelligence computing then combined this data with 10 key soil, topography and climate factors to create a global map of where trees could grow.

This showed that about two-thirds of all land - 8.7bn ha - could support forest, and that 5.5bn ha already has trees. Of the 3.2bn ha of treeless land, 1.5bn ha is used for growing food, leaving 1.7bn of potential forest land in areas that were previously degraded or sparsely vegetated.

"This research is excellent," said Joseph Poore, an environmental researcher at the Queen's College, University of Oxford. "It presents an ambitious but essential vision for climate and biodiversity." But he said many of the reforestation areas identified are currently grazed by livestock including, for example, large parts of Ireland.

"Without freeing up the billions of hectares we use to produce meat and milk, this ambition is not realisable," he said. Crowther said his work predicted just two to three trees per field for most pasture: "Restoring trees at [low] density is not mutually exclusive with grazing. In fact many studies suggest sheep and cattle do better if there are a few trees in the field."

Crowther also said the potential to grow trees alongside crops such as coffee, cocoa and berries - called agro-forestry - had not been included in the calculation of tree restoration potential, and neither had hedgerows: "Our estimate of 0.9bn hectares [of canopy cover] is reasonably conservative."

However, some scientists said the estimated amount of carbon that mass tree planting could suck from the air was too high. Prof Simon Lewis, at University College London, said the carbon already in the land before tree planting was not accounted for and that it takes hundreds of years to achieve maximum storage. He pointed to a scenario from the Intergovernmental Panel on Climate Change 1.5C report of 57bn tonnes of carbon sequestered by new forests this century.

Other scientists said avoiding monoculture plantation forests and respecting local and indigenous people were crucial to ensuring reforestation succeeds in cutting carbon and boosting wildlife.

Earlier research by Crowther's team calculated that there are currently about 3tn trees in the world, which is about half the number that existed before the rise of human civilisation. "We still have a net loss of about 10bn trees a year," Crowther said.
Visit the Crowther Lab website for a tool that enables users to look at particular places and identify the areas for restoration and which tree species are native there.

This article was amended on 18 October 2019 to reflect a revision made to the original research paper, and a clarification in a letter by the authors of the study in the journal Science, that responds to criticism of their work. They clarify that one comparison made did not take into account that 55% of the CO2 produced by human activity is absorbed by land and oceans. The text of the first and second paragraph of this article have been edited to reflect this and the paper revision. The article was further amended on 31 August 2021 when text stating that "research estimates that a worldwide planting programme could remove two-thirds of all the emissions from human activities that remain in the atmosphere" was changed to refer to "just under one-third", to reflect a subsequent erratum published by the report's authors.

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Tree planting 'has mind-blowing potential' to tackle climate crisis

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Research shows a trillion trees could be planted to capture huge amount of carbon dioxide

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Trillion Trees is delighted to have been selected as an official Nominator for the prestigious Earthshot Prize. The Prize was developed to search the world and identify solutions to repair our planet. There are five Earthshots, with one winner in each category receiving £1,000,000 to continue and scale their work.

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Can Planting a Trillion Trees Stop Climate Change? Scientists Say it’s a Lot More Complicated

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Can Planting a Trillion Trees Stop Climate Change? Scientists Say it’s a Lot More Complicated

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Bob Berwyn Inside Climate News | 2020

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Compared with cutting fossil fuels, tree planting would play only a small role in combating the climate crisis.

It seems simple. Plant enough trees to soak up all the carbon dioxide released by burning fossil fuels and people can forget about global warming and get on with their lives.

The idea even resonates with President Trump who, in January, said he backs an international " trillion trees" plan "to protect the environment."

Trump's endorsement, at the Davos World Economic Forum, grabbed headlines, coming from a president who has withdrawn from the Paris Agreement, dismantled environmental regulations aimed at reducing emissions and called climate change a "hoax." In the same speech, he attacked young climate activists as "prophets of doom."

Since Davos, the tree planting plan has morphed on Capitol Hill into the so-called Trillion Trees Act, a proposed bill that would set targets for increasing wood growth to capture carbon, part of a growing global focus on nature-based climate solutions to complement greenhouse gas reduction efforts.

Internationally, the WWF, BirdLife International and the Wildlife Conservation Society formed TrillionTrees.org to "protect and restore" forests, while the Davos discussions spurred formation of 1t.org as a global platform to mobilize funds that leans heavily on commercial forest interests. There's even a tree-based cryptocurrency.

How to plant a trillion trees is a wide-open question, however. Forest scientists warn that massive tree planting programs could have unexpected consequences, and that cutting fossil fuel emissions is far more important in fighting global warming. A more useful focus, they say, is to preserve and bolster the forests we already have.

Fossil fuel burning and fires emit about 11 gigatons of carbon per year; forests, fields, grasslands and oceans absorb about 6 gigatons. So every year, about 5 gigatons go into the atmosphere. More trees could reduce the excess carbon dioxide that is warming the planet.

The idea that trees can help limit global warming is enshrined in the 2015 Paris climate agreement, with most countries including forest expansion as part of their plans to reduce emissions. Reports and studies from the Intergovernmental Panel on Climate Change estimate that nature-based solutions, including healthy forests, could provide up to one-third of the emissions reductions required by 2030 to meet the Paris Agreement targets.

A 2019 Swiss study, for example, estimated that globally, there was the potential to protect and regrow trees on about 3.5 million square miles of land (an area a little smaller than the United States). Doing so, the study projected, would increase the global forest cover by 25 percent and capture and store about a quarter of the carbon in the atmosphere when the forests matured.

Those figures are disputed, but the research has increased interest in the trillion trees idea, and the study is one of the supporting documents for the Trillion Trees Act in Congress.

Separate from the U.S. political process, the international Trillion Trees initiative promoted by the conservation coalition wants to protect and regrow one trillion trees around the world by 2050. The main focus is to protect key forests like the Amazon, and to support natural regrowth in logged areas.

Additionally, the 1T.org platform, launched after the Davos conference, with major partners like Salesforce, Microsoft and Deloit, is aiming to accelerate forest restoration and conservation by finding financing, for example, with app-based crowdfunding. That could help pay for high-tech tools like satellite data and artificial intelligence to guide precision forestry and to monitor tree and soil carbon storage.

Forest Politics

In the United States, the trillion trees idea has taken the form of the Trillion Trees Act, a proposed bill that calls on the United States to take a leadership role in planting a trillion trees globally as a "pragmatic step toward addressing global carbon emissions."

The measure was introduced by Rep. Bruce Westerman, an Arkansas Republican, on Feb. 12. At a Feb. 26 congressional hearing, House Resources Committee Chairman, Rep. Raúl Grijalva, (D-Ariz.), said the proposed bill could open the door to bipartisan progress on climate action.

"For too long, my friends on the other side of the aisle denied that this was even a real issue," Grijalva said during the hearing. "They would reject, or even mock, the overwhelming scientific consensus that the planet is warming, humans are responsible, and urgent action needs to be taken."

He added, "I welcome Republicans into what is hopefully a new chapter for their party focused on climate solutions, not climate denial."

President Donald Trump and First Lady Melania Trump participate in a tree planting ceremony with French President Emmanuel Macron and his wife Brigitte Macron on the South Lawn of the White House on April 23, 2018. Credit: Jim Watson/AFP via Getty Images

Democrats simultaneously introduced HR 5435, the American Public Lands and Waters Climate Solution Act of 2019, which would first set a net-zero emissions target and require public lands to be managed to reduce greenhouse gas emissions. Neither bill has advanced out of committee.

Another measure that could encourage tree planting has been floated in the Senate by Colorado Democrat Michael Bennet (D-Colo.), with tax credits for "farmers and ranchers, state and local governments and tribes, to sequester carbon in agriculture, forestry, rangelands and wetlands."

Westerman called trees the "ultimate carbon sequestration device," and said his bill turns science into practical solutions. Support for the measure came from wood industry lobbyist Steve Marshall, who said the bill could support efforts to use more wood for building material as a way to store carbon long-term.

"We have an obligation to conserve our resources and make them available to future generations, and I challenge anyone to find a better climate solution than taking care of our forests."

Just Planting Trees is Not Enough

Climate scientists and many Democrats on the House committee greeted the proposed tree planting legislation skeptically, saying that the only real climate solution is to cut greenhouse gas emissions to zero as soon as possible.

Forests can only be part of a long-term plan to curb global warming after that happens, Yale evolutionary biologist and ecologist Carla Staver testified at the Trillion Trees Act hearing.

"Our primary focus must be reducing our dependence on fossil fuels," she said, adding that any plausible attempt to limit global warming within our lifespan must also include forest protection and reforestation. "However, it is also crystal clear that tree planting alone will not fix our ongoing climate emergency," she said.

In February, a coalition of 95 environmental groups sent a letter to Congress opposing the Trillion Trees Act as the "worst kind of greenwashing and a complete distraction from urgently needed reductions in fossil fuel pollution."

As written now, the proposed law would count biofuel from forests as carbon neutral, a claim that's contested by climate advocates and scientists, who have said the push to burn wood for fuel actually threatens global climate goals. It would also limit public and judicial reviews of forest management and even create incentives for more logging of existing old-growth forests, which are the best existing carbon sinks, said Alexander Rudee, a forest policy analyst with the World Resources Institute.

"Requiring harvests to increase annually will likely cause a net loss of trees, at least in the short-term, since natural regeneration isn't 100 percent effective, and could increase emissions from burning or decomposing harvest residues," Rudee said.

Magical Thinking

One reason the trillion-tree meme caught on may be that the world wants a simple solution to climate change and is ready for a positive message. Everyone can picture the act of placing a seedling in the ground and helping it grow, a nurturing symbol that must be part of our earliest collective memories as a species.

But Colorado State University atmospheric scientist Scott Denning, who studies how carbon moves through the global climate system, said the basic numbers of the trillion trees story don't add up.

"No doubt, if you replaced every area of non-forest with forest, you could sequester a lot of carbon," Denning said. "But very little of the world is available for planting a trillion trees. Most of the land that might be suitable is in use for farms and cities. Most of the places that can support forests, like the Amazon, Congo, Indonesia and Southeast Asia, already have forests."

He added, "You have to fix global warming by stopping burning oil and gas. To think you can just plant trees and keep burning oil and gas doesn't make sense. We have to to get away from magical thinking."

And while trees might help the planet survive in the long run, scientists say, first we have to save them. Global warming is a threat-multiplier for drought, fires and pests that have killed trees across millions of acres in the last 20 years. And forests all over the world are already in the full grip of the climate crisis, said University of Arizona ecohydrologist David Breshears.

The forests around Breshears' lab in Tuscon, near the shrinking southern end of the western North American forest belt, have been one of the mortality hotspots for trees. Planting a trillion trees around the world wouldn't change that, he said.

"We'd like more trees to slow down the warming. But the warming we're trying to slow is killing the trees. There's real concern that we're going to be losing a lot of trees, with more frequent die-offs.

"We need to hold on to the trees that we have," Breshears said.

University of Montana scientist Diana Six says that widespread tree planting, like everything else we do with nature, requires caution.

"People think, what could be bad about planting more trees, but few have the background to understand the ecological issues," she said, adding that any major tree-planting program needs to look closely at many related factors, including water and potential social impacts like the dislocation of communities.

"People think they're going to put these trees in and they'll grow and live happily ever after," Six said. "A lot of places that don't have trees are just too dry-you can't just stick them in the ground and poof, have a new forest. And they don't think about the time frame of trees.

"These trees are going to have to grow well and live a long time and not be prone to disease and insects, to capture a lot of carbon," she said. "This is a multigenerational commitment to take care of these forests. They can't be harvested, and you can't just plant them and walk off."

Future of the Amazon

The rapid forest changes underway might be a sign that it's time to develop plans to save existing forests before trying to engineer the climate with tree plantations, a panel of international scientists said last week during a streamed discussion at this year's virtual European Geosciences Union assembly.

Scientists on the panel said limiting global warming damage and stopping the deforestation of the Amazon Rainforest should be the highest item on the forest agenda, because there are signs that this vital part of the planet's ecosystem is failing.

Observations in rainforests and research in labs can help project what's ahead for warming forests. In the University of Arizona's Biosphere 2 habitat, scientists simulate rainforest conditions, then turn the sprinkler off. Such experiments, together with the onsite measurements, suggest that parts of the Amazon are already emitting more carbon dioxide than they capture.

Increasing drought could push even more of the rainforest over the tipping point, a recent study concluded. In the deforested eastern part of the Amazon, carbon dioxide emissions are already nine times as high as in the relatively undisturbed western part, said Brazilian forest scientist Luciana Vanni Gatti, lead author of the study.

"We think that we know everything about nature, but we don't," she said. "I imagine nature like a domino. We understand the first, second, third, and maybe, some illuminated minds, the fourth. But when we make changes to nature, the dominoes fall, and that can have consequences on a very large scale."

Some scientists say there are areas where forest restoration could help in the long-term effort to curb greenhouse gas heating, including the Atlantic Forest zone of Brazil, which has been stripped of trees over the last 200 to 300 years.

But in the May 8 issue of the journal , University of California, Santa Cruz restoration ecologist Karen Holl wrote that simplistic tree-planting formulations can overshadow other actions that could do more to slow global warming, like quickly reducing deforestation and cutting greenhouse gas emissions.

"The forest carbon bill proposed in Congress is not going to fix global warming, because we can't plant our way out of climate change," she said.

Tree-planting plans have to make sure that projects don't displace food production and living space, and they have to include a long-term commitment to land protection, management and funding, she added.

"People love trees, and there are good reasons they love trees," Holl said. "We're not saying tree-planting is bad. But it's more complicated than it seems."

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Can Planting a Trillion Trees Stop Climate Change? Scientists Say it's a Lot More Complicated - Inside Climate News

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It seems simple. Plant enough trees to soak up all the carbon dioxide released by burning fossil fuels and people can forget about global warming and get on with their lives. The idea even resonates with President Trump who, in January, said he backs an international "trillion trees" plan "to protect the environment."

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Everyone Can Plant a Tree & Help Fight Climate Change

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Everyone Can Plant a Tree & Help Fight Climate Change

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Arbor Day

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Planting trees is a simple thing everyone can do to reduce carbon dioxide, a principal greenhouse gas that contributes to climate change. No matter where you live, you can plant trees...and take a proactive, positive step toward keeping our planet healthy.

Plant trees in your yard and around your home. They'll provide shade to cool your home in summer and windbreaks to reduce cold winds in winter - reducing your energy needs.

Plant trees in your community - in parks, around schools, and in urban areas. Trees help shade buildings and pavement, reducing the heat-island effect and conserving energy.

Plant trees on your farm or rural property. Trees and woody agriculture also protect soil, provide wildlife habitat, shade your home, create windbreaks, and keep streams and rivers clean, while helping to fight climate change.

Plant trees in our national forests. You'll also be helping to restore these beautiful national treasures for future generations to enjoy.

More:

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Everyone Can Plant a Tree - Climate Change at arborday.org

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Planting trees is a simple thing everyone can do to reduce carbon dioxide, a principal greenhouse gas that contributes to climate change. No matter where you live, you can plant trees...and take a proactive, positive step toward keeping our planet healthy. Plant trees in your yard and around your home.

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How Trees Fight Climate Change in Your Community

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How Trees Fight Climate Change in Your Community

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Arbor Day Foundation

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Neighborhood and street trees provide shade for streets and parking areas, add to the value of your property, cool the air, and absorb carbon dioxide.

Neighborhoods with well-shaded streets can be up to 6-10° F cooler than neighborhoods without street trees, reducing the heat-island effect (see illustration below), and reducing energy needs.(U.S. Forest Service Center for Urban Forest Research)

Shaded parking lots keep automobiles cooler, reducing emissions from fuel tanks and engines, and helping reduce the heat-island effect in communities. (U.S. Forest Service)

Is your community a Tree City USA ®? Support Tree City USA where you live.

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Trees Can Help Fight Climate Change in Your Community - Climate Change at arborday.org

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Neighborhoods with well-shaded streets can be up to 6-10° F cooler than neighborhoods without street trees, reducing the heat-island effect (see illustration below), and reducing energy needs.(U.S. Forest Service Center for Urban Forest Research) Shaded parking lots keep automobiles cooler, reducing emissions from fuel tanks and engines, and helping reduce the heat-island effect in communities.

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Kids Encyclopedia Facts

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Deforestation is when forests are destroyed by cutting trees ( logging) and not replanting them. The most common reason is to clear the land to make farms, ranches, and cities. Trees are also cut for firewood and lumber.

Deforestation destroys the habitat of many animals, leading to their death and possible extinction. The loss is more severe in primary forests, which are forests that have yet been untouched by humans. Deforestation also releases sequestered carbon.

Restoring trees in deforested places is called reforesting.

Benefit of forests

Forests are often planted to protect against natural disasters. They also help the water cycle function properly. When forests are lost, very often the soil they protected is also lost. This loss of soil is called erosion.

Trees are also important for carbon sequestration. They are important in keeping the proper balance of oxygen (O ₂) and carbon dioxide (CO ₂) on earth. They take in carbon dioxide that humans exhale (breathe out) and release oxygen that humans inhale (breathe in).

Forests have the following functions:

regulating the water cycle

producing soil

preventing soil erosion

providing habitat for animals

providing most of our oxygen

maintaining the proper oxygen (O₂) and carbon dioxide (CO₂) levels

balancing the atmosphere

regulating the temperature

Global deforestation suddenly increased around 1852. As of 1947, the planet had 5.8 million to 6.2 million sq. mi. (15 million to 16 million km ²) of mature tropical forests (forested landscapes in tropical regions), but by 2015, it was estimated that about half of these had been destroyed. Total land coverage by tropical rainforests decreased from 14% to 6%. Much of this loss happened between 1960 and 1990. Scientists have calculated that at this rate, the extinction of such forests could happen by the mid-21st century.

Causes of deforestation

Land has other uses besides growing trees. The biggest uses of land that was once forested are for farming and ranching. Some land is also used for roads and buildings, especially in urban areas. As the population grows, people need to remove more trees. They also use the wood from the trees as lumber to make buildings and other things, or they burn the trees as firewood.

Environmental effects

Atmospheric

Further information: Deforestation and climate change

Deforestation is ongoing and is shaping climate and geography.

When the trees burn or rot, the small amount of carbon that is not absorbed by the soil can return to the atmosphere in the form of carbon dioxide. Scientists believe that since carbon dioxide is a greenhouse gas, deforestation can cause global warming. They have estimated that tropical deforestation is responsible for about 20% of world greenhouse gas emissions.

Hydrological

The water cycle is also affected by deforestation. Trees play an important part in the proper working of the water cycle.

Their canopies catch precipitation, which is then evaporated back to the atmosphere (canopy interception). Without canopy interception, the air would be drier and less precipitation would fall.

Their litter (plant material on the ground around the tree), stems, and trunks slow down surface runoff. Without these, flash flooding would be more likely.

Their roots create macropores - large pipe-like trails - in the soil that increase infiltration of water. Without these trails, water would not flow through the soil as easily.

They absorb groundwater from the soil and transpire moisture into the atmosphere. Without transpiration, the air would be drier and trees would not get the moisture they need because of the lack of precipitation.

Tropical rainforests produce about 30% of our planet's fresh water.

Deforestation changes normal weather patterns, creating hotter and drier weather. This results in more drought, crop failures, melting of polar ice caps, and coastal flooding.

Undisturbed forests do not have much erosion because of plant litter on the ground. Plant litter protects from surface runoff. Forestry operations also increase erosion because of the roads and mechanical equipment they use.

Deforestation in China's Loess Plateau many years ago led to soil erosion. This erosion caused valleys to open. The increase of soil in the runoff causes the Yellow River to flood and makes it yellow-colored.

Erosion is not always a consequence of deforestation. An example would be the southwestern regions of the United States. The loss of grass due to the presence of trees and other shrubbery leads to more erosion than when trees are removed.

Soils are reinforced by the presence of trees, which secure the soil by binding their roots to soil bedrock. When trees are removed on sloped lands, those lands are more likely to have a landslide.

Biodiversity

Forests support biodiversity, providing a habitat for wildlife. Forests also produce medicinal plants. Tropical rainforests are the most diverse ecosystems on Earth and about 80% of the world's known biodiversity could be found in tropical rainforests. When humans remove or destroy large areas of forest cover, the soil degrades and biodiversity is lessened. Some species of plants and animals can become extinct. Some scientists predict that more than 40% of the animal and plant species in Southeast Asia could be wiped out in the 21st century. Other scientists show data that disagree with this prediction.

Health effects

Public health context

Some scientists believe that deforestation exposes people to zoonotic diseases (diseases that can be passed from an animal to a human). Dieseases that are associated with the forest include malaria, Chagas disease (also known as American trypanosomiasis), African trypanosomiasis ( sleeping sickness), leishmaniasis, the Nipah virus, Avian flu, Swine Flu, Lyme disease, HIV, and Ebola.

General overview

According to the World Economic Forum, 31% of emerging diseases are linked to deforestation. According to the US Centers for Disease Control and Prevention (CDC), 75% of emerging diseases in humans came from animals.

In 2016, the United Nations Environment Programme published the UNEP Frontiers 2016 Report. The report shows the causes of emerging diseases:

The latest appearing diseases and their causes are listed on page 23 of the report:

Economic impact

According to the World Economic Forum, half of the global GDP depends on nature. For every dollar spent on nature restoration, there is a profit of at least 9 dollars.

People in both developed and developing countries use wood for building, wood for fuel, and wood pulp for paper. In developing countries, almost three billion people rely on wood for heating and cooking. The economy does well in the short term when trees are cut to make products, but usually, not enough trees can be planted in their place in time for more to be cut down again when they are needed. This causes the economy in the long term to suffer.

Illegal logging causes billions of dollars of losses to national economies each year. The European Union is one of the largest importers of products made from illegal deforestation.

Many countries have taken steps to control deforestation. They have begun programs that they hope will help with the problem.

Reducing emissions: The United Nations and the World Bank have begun to develop programs to reduce deforestation. Because trees take in carbon dioxide, the more trees we have, the less CO₂ will be emitted into the air. Reducing Emissions from Deforestation and Forest Degradation (REDD) is a program that offers money or other incentives (good consequences as a result of an action) to developing countries if they use different ways to build than using the forest's trees.

Government and private policies: In the government area, laws could be made to protect forests, making it illegal to cut trees down without special permission. Private companies could promise to use the land they own the best way they can and to buy products only from companies that do not use deforestation. The Paris Agreement is an example of this.

Land rights: Another way to conserve forests is to change the right to use the land from the public domain to the indigenous inhabitants.

Farming practices: New ways to farm are being developed to get more use out of a single piece of land rather than having to use many pieces of land for different purposes. For instance, in cyclic agriculture, cattle are grazed on farmland that is resting and rejuvenating. The cattle help the land prepare for future plantings by dropping nutrients (from their feces) into the soil.

Monitoring deforestation: Satellite images can help scientists know where on the earth they need to concentrate their efforts in fighting deforestation.

Forest management: Planning ahead by planting more trees than we think will be necessary for future generations is one way to manage our forests well. Reforestation in areas where trees have been cut is another way to manage our forests well. In the areas where "slash-and-burn" is practiced, switching to "slash-and-char" would make the soil rich and healthy for future trees.

Sustainable practices: Bamboo grows and is ready for use faster than trees. Using bamboo rather than wood for building and making products would reduce the need to cut down trees.

Forest plantations: Some places have forest plantations, which are large plots of land that have trees planted on them in an orderly way. They produce more healthy trees per acre than a natural forest.

Interesting facts about deforestation

More than half the world's tropical forests have been destroyed since the 1960s.

In 2019, the world lost an entire soccer field worth of primary rainforest every six seconds.

Forests release carbon dioxide when they are cleared or burned. About 12 percent of global greenhouse gas emissions come from deforestation.

It is estimated that within 100 years, there will be no rainforests.

20% of the world's oxygen is produced in the Amazon forest.

Almost half of the world's timber and up to 70% of paper is consumed by Europe, the United States, and Japan alone.

Worldwide, more than 1.6 billion people rely on forest products for all or part of their livelihoods.

Related pages

Images for kids

In Spanish: Deforestación para niños

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What Is Deforestation For Kids: Information And Facts

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What Is Deforestation For Kids: Information And Facts

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Active Wild | 2015

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What Is Deforestation For Kids: Information And Facts

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What is deforestation? Information & facts about deforestation for kids. Why are areas of rainforest being lost each year & what is being done to stop it?

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See the Forests challenge in the Earth Day Ecochallenge Event

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Forests are treasure troves of biodiversity: eight out of ten land-based species live in forests, as well as almost 300 million people. Forests offer food, shelter, medicine, ecosystem services, and many of the raw materials that create the products people rely upon in our daily lives.

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How Does Climate Change Impact Plants And Animals?

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How Does Climate Change Impact Plants And Animals?

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Feb 21, 2017 | Peggy Notebaert Nature Museum

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How Does Climate Change Impact Plants And Animals?

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climate change - Podcast - In Defense of Plants

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What do street trees and oceanic islands have in common? It turns out a lot, at least from an ecological perspective. I sit down with Dr. Robert Warren to explore questions like do street trees constitute a functioning forest or a beautiful garden? What role do humans play in the ecology of street trees?

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Can We Plant Enough Trees To Fix Global Warming?

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Can We Plant Enough Trees To Fix Global Warming?

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Can We Plant Enough Trees To Fix Global Warming?

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In general, the carbon dioxide cycle works this way- plants pull CO2 out of the air, people or animals eat those plants, and then breathe CO2 back out. Before the industrial revolution, the amount of CO2 that was pulled out of the air, and the amount returning to it, was balanced.

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Not Cool Ep 20: Deborah Lawrence on deforestation

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Not Cool Ep 20: Deborah Lawrence on deforestation

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This summer, the world watched in near-universal horror as thousands of square miles of rainforest went up in flames. But what exactly makes forests so precious - and deforestation so costly? On the 20th episode of Not Cool, Ariel explores the many ways in which forests impact the global climate - and the profound price we pay when we destroy them. She's joined by Deborah Lawrence, Environmental Science Professor at the University of Virginia whose research focuses on the ecological effects of tropical deforestation. Deborah discusses the causes of this year's Amazon rain forest fires, the varying climate impacts of different types of forests, and the relationship between deforestation, agriculture, and carbon emissions. She also explains why the Amazon is not the lungs of the planet, what makes tropical forests so good at global cooling, and how putting a price on carbon emissions could slow deforestation.

Topics discussed include:

Amazon rain forest fires

Deforestation of the rainforest

Tipping points in deforestation

Climate impacts of forests: local vs. global

Evapotranspiration

Why tropical forests do the most cooling

Non-climate impacts of forests

Global rate of deforestation

Why the amazon is not the lungs of the planet

Impacts of agriculture on forests

Using degraded land for new crops

Connection between forests and other greenhouse gases

Individual actions and policies

References discussed include:

There's plenty of reasons why we want to keep forests. They regulate the hydrological cycle. They tend to minimize flooding; they manage flows in rivers. They are kind of like a sponge, so they take up rainfall or snowfall and then they trickle it out slowly, so that it's available for us or ecosystems or agriculture.
~ Deborah Lawrence

Ariel Conn: Welcome back to Not Cool, a climate podcast. I'm your host, Ariel Conn. Today's interview is one I'd been looking forward to for a while. To be clear: I have loved every minute of every interview I've done for this podcast, but trees hold a very special place in my heart. They can grow so tall, live so long, purify our air, positively impact our climate, improve our moods, they're just generally awe-inspiring, and that doesn't even get into the science of how they grow, thrive and possibly even communicate with each other. The more I learn about trees, the more amazed I become. So, I'm very excited that for episode 20, we're joined by Deborah Lawrence, who will talk about the impact of forests on climate change, along with the impact humans have had on forests.

Deborah is a Professor of Environmental Sciences at the University of Virginia, where her research focuses on the ecological effects of tropical deforestation. She has spent the past twenty-five years doing field-based research in Indonesia, Costa Rica, Mexico and Cameroon. She and her students conduct interdisciplinary research with partners in economics, anthropology, geography and hydrology to understand the drivers and consequences of land use change.

Focusing on tropical forests and climate change, she participated in the international negotiations of the United Nations Framework Convention on Climate Change (UNFCCC), she supported the US delegation to the World Bank Forest Carbon Partnership Facility and Forest Investment Program, and she was part of several inter-agency missions on reducing emissions from deforestation and degradation (REDD+) in Indonesia and Southeast Asia.

Deborah, thank you so much for joining the podcast.

Deborah Lawrence: Glad to be here.

Ariel Conn: Pretty recently in the last month or so in the news, the Amazon rainforest was getting a lot of attention because it was burning - very, very significantly. So before I get into any other questions I have for you, I was wondering if you could just give us an update of what's going on in the Amazon this year. Why were the fires so big? How do they compare to previous years? Why is this so bad?

Deborah Lawrence: Okay. The Amazon burns every year, so it's not really new - but there were more fires this year, and significantly so. I don't think it's twice as many, but I think it's high. So the question is, what does that mean and why is it happening? The reason it happens is because people are trying to cut the forest to either grow crops like soy or to create pastures for cattle. So these are big worldwide commodities. This is a major activity of the Brazilian Amazon for sure.

The question is, why would it spike this year? And I think the answer is not some quirk of climate. It's not because it's a super hot year. It's because the president of Brazil has indicated that he is not going to be enforcing the existing laws that protect the Amazon. So that sounds kind of strong. But he has indicated that he is not really that concerned that the Amazon remain intact. He sees the Amazon as an incredible resource for Brazil, and he is interested in using that resource to advance the economic development of the country. That is a change. Formerly, the leadership has felt that the Amazon was important as a block of forest, and in fact respected the many laws that they had created over the past decade or so to protect it. Some of those laws are really quite progressive. They give rights to indigenous people to manage forests, and they promise that ownership is true and protected by the government.

So the wonderful thing about these laws that they created over the last 10 to 15 years is that they have dramatically reduced deforestation in Brazil. The increase in fires has to be taken in the context of the fact that there had been really an incredible success story in the Amazon over the past decade. Deforestation had come way down. So even though this year there's a lot of fire, it's not as bad as it was 10 or 15 years ago; not nearly as bad. What I think of when I think of the Amazon burning is this is just a harbinger of things to come. It's not suddenly a problem. It's the fact that it looks like it's going in the wrong direction.

Ariel Conn: That's actually really interesting, because I definitely remember for quite a while hearing about how we have to save the rainforest - and there was lots of news about it, lots of coverage, and then that sort of seemed to go away. So it sounds like maybe a lot of these laws had been to address that, and were working.

Deborah Lawrence: I think that's the case. Now, the rainforest doesn't just exist in the Amazon. There are really important forests throughout the tropics, and we still need to save the rainforest. There's still a lot of threats to the rainforest. In southeast Asia they grow oil palm, and they do that by clearing rainforest. In central Africa they are putting in pastures and they're also expanding oil palm, and in the Amazon they're expanding oil palm. So there's still a reason to worry about the rainforest, but things had indeed been getting better.

Ariel Conn: You mentioned some of these other forests. I guess maybe before we get to those - because I want to ask about them as well - why do we care so much about the Amazon, and also just how big is it?

Deborah Lawrence: So the Amazon is 2.1 million square miles.

Deborah Lawrence: Yeah, that's pretty big. It has pieces of French Guiana, Suriname, Guyana, a tiny bit of Venezuela, Colombia, Ecuador, Peru, Bolivia, and Brazil. It touches all those countries.

Ariel Conn: But it's primarily in Brazil.

Deborah Lawrence: Brazil, Peru, and Bolivia, yeah. But mostly Brazil. That's why we talk about Brazil.

Ariel Conn: Okay. So their policies have changed recently, but it sounds like that's very short-term thinking because everything I hear is that the Amazon plays a major role in our climate, and so if we're not taking care of it, not only does it affect the whole world, it's still going to also negatively impact Brazil. Is that true?

Deborah Lawrence: That is true. The way we understand the importance of the Amazon is partly by using models to explore what happens when we take it away. You have to believe that a model can capture the dynamics of this very complex ecosystem and climate system, and they do a pretty good job. And you also look across many models to try to understand what happens if you take out the Amazon.

I think some of the most interesting work has been to look at what happens with the progressive deforestation of the Amazon: 10%, 20%, 30%, 40% gone. And what you see is that across different models with different modeling groups, it looks like there is some kind of tipping point at which you go from a system that it is stressed but still a rainforest to a system where suddenly it's really much hotter and drier. And so even though you haven't deforested the rest of the Amazon, you end up with a different kind of forest because it's stressed out. It's dryer and it has higher mortality, so it goes from something that looks more like a rainforest to something that looks more like a scrubby savanna.

There's the notion that these tipping points can occur because of internal dynamics in the system. We're not talking about climate change. We're just talking about what I call the other climate change: the fact that when you cut the forest down, you affect the climate system right there, and you also affect the climate system elsewhere.

Ariel Conn: I'm going to come back to this idea of tipping points, but first, can you talk about the different impacts different types of forests have? If it's not a rainforest, it's having a different impact. In Colorado, I see lots of forests, but it's obviously a very different type of forest than a rainforest.

Deborah Lawrence: Right.

Ariel Conn: So what's the different impact on the climate?

Deborah Lawrence: Fundamentally, there's two types of ways that forests affect climate. One is through their impact on the carbon cycle, meaning how much carbon do they store in their biomass, in their soils? Because forests take up CO2 through photosynthesis. They're one of the ways that we get rid of the excess CO2 that humans add to the atmosphere - it's through uptake of these forests. So one way to evaluate different types of forest is to say, well, how much carbon does it hold? How much carbon does it draw down every year? And on that metric, tropical forests are phenomenal. They take up so much carbon. There are some rainforests in the northwest of the United States; they also have high carbon. So rainforests everywhere have high carbon concentrations. Almost any other forest you have just doesn't have as much carbon in it. So there's the carbon story and there are some high carbon forests in the northern hemisphere, but taken as a whole, most of the carbon rich forests are in the tropics.

The other way that forests affect climate is through what they do to the balance of energy and water. And there's sort of two things that happen. The sun shines down on a forest, and the forest has to do something with the energy. If it absorbs it, which most forests do because they're quite dark, it has to do something with the energy. It can radiate it back as heat, or it can use that energy to transform water from liquid to vapor. And it does that by sucking water out of the roots, up through the leaves, and then out to the atmosphere. And when it leaves the leaf surface, it's no longer liquid water - it's vapor. And that process cools the atmosphere right above the forest; it also changes the energy balance there so that the dynamics of the atmosphere above the forest change.

So you might've heard about atmospheric rivers. These rivers are basically descriptions of the fact that the atmosphere has these circulation patterns in it, and that one of the ways that that circulation pattern is defined is based on what the plants are doing below that atmosphere. Trees move a lot of water, so even though they absorb a lot of incoming radiation, they take that and they turn it into water vapor. They change the energy form, they change the water cycle, and they actually turn that energy into something else, into latent heat. So it's kind of wonderful that these forests, where there's so much incoming solar radiation at the tropics - they take a lot of that and instead of turning into heat, they turn it into something that cools locally and eventually can cool further away.

Ariel Conn: You were talking earlier about how the forests impact the local climate, and I'm guessing this is what you were referring to?

Deborah Lawrence: Correct.

Ariel Conn: How far does that spread then?

Deborah Lawrence: Well, there's another layer here. All forests tend to be dark, and all forests have the capacity to move a lot of water. It's evapotranspiration. Whether they do that depends partly on where they are on the planet. It turns out that the forests respond to incoming solar radiation differently, and the further north you go - like up past the temperate zone into the boreal forest - those forests tend to absorb radiation and just hold it. Forests in the far north actually warm the planet. In the temperate zone, it's a mixed bag; some forests are more warming and some forests are more cooling. But in the tropics, forests are really cooling.

The interesting thing is that when you put forests into the high north, like the high latitudes, they will actually absorb more heat and warm the local area, and because they mask the snow, they actually change the reflectivity of that whole area. They make a light surface with no trees into a dark surface that blocks out the snow. So what would have been a very reflective place, and very cold, suddenly is much warmer. In the boreal zone, those forests then not only warm locally, but through a lot of feedbacks with the ice and snow and the oceans, they send that warming around the globe.

The corollary is when you take forests away in the boreal zone, boy does it cool the planet down. Because they have so much snow cover, and ice, and those feedbacks that connect changes on the land to changes in the ocean, you get a really strong cooling. So it just shows how powerful those forests are in the far north. And again in the temperate zone, there's a lot of variability in exactly what latitude forests go from being a net cooling to being a net warming. Just depends on the study. So there's still work to be done to understand exactly whether those forests are generally warming or cooling for the planet.

However, ironically, the very local impact of forests is always cooling locally. And this might sound like it doesn't make sense: how can you have local cooling but then global warming? And it's because there is still that cooling effect of evapotranspiration in the summer. So if you think about where is it going to be hot in the future, it's going to be hot everywhere in the growing season. So in the growing season it's a great idea to have a forest nearby, because during the growing season evapotranspiration is high. They're moving a lot of water because they have a higher level of incoming radiation, and they actually can get some cooling. But in the winter, in the spring, those same forests with their same forest cover - they end up warming.

So you can have this effect of, it's good to have the forest in the summer when it's hot because it'll keep you cool, but in the winter and spring when you expect to get a bunch of cooling for the whole planet, you don't get that cooling. You get warming. So for the local planner, they probably want to worry about extreme heat in the summer, so they probably want that forest. And that effect is true for everywhere. It's just that that balance between a local effect and a global effect changes depending on latitude.

Ariel Conn: I want to go back real quick to something you said. Did you say that removing the boreal forests causes global cooling? Did I understand that right?

Deborah Lawrence: That is what the models show, that if you were to just get rid of all of the boreal forests, it would cool the planet a lot.

Ariel Conn: I'm assuming there's a reason we don't want to do that, though?

Deborah Lawrence: Well, there's plenty of reasons why we want to keep forests. They do other things, like they regulate the hydrological cycle. They tend to minimize flooding; they manage flows in rivers. They are kind of like a sponge, so they take up rainfall or snowfall and then they trickle it out slowly so that it's available for us or ecosystems or agriculture.

There's other reasons to keep forests around. I don't think we're going to deforest the boreal zone anytime soon. I would say that if we had to figure out where we should be getting our timber, I would perhaps say that there would be reasons to think about timber extraction in the boreal instead of timber extraction in the tropics, because the tropics give us both the local and regional cooling and they do so much for the planet.

Ariel Conn: Let's come back to the agriculture aspect too. So one of the things that you're saying, if I'm understanding you correctly - in order for us to have better agricultural practices, it's best to have a forest nearby, and yet we're cutting down all the forests precisely for agriculture. Is that correct?

Deborah Lawrence: That is correct. That's why you cut a forest; at least that's traditionally been why. The thing that we've been talking about so much is temperature, and temperature is super important, but the other factor is rainfall. And the idea is that forests regulate water flows as well as flows of energy, and so when you have a forest nearby, and the air passes across that forest, research has shown that it will deliver more rain downwind. So if you have agriculture somewhere, you want to have a giant block of forest upwind. You want to have a supply of moisture.

Forests take that water out of the soil, they pump it up through their leaves and back into the atmosphere. They're like a source for atmospheric moisture that ultimately, as it moves downwind, condenses and becomes rain. I mean, unless you're right next to the ocean and you have a big source of water and moisture coming off the ocean, you really want to have forests nearby so that they can provide moisture to the atmosphere, which then provides moisture to our crops.

Ariel Conn: And so what happens if we don't get this destruction of the Amazon rainforest under control?

Deborah Lawrence: It would be a really sad thing, not only because the agriculture that people were planning on might suffer, but because that rainforest is really quite amazing. It has an incredible diversity of flora and fauna and people, and it would be a shame if we lost it - especially if we lost it because of some tipping point where we thought we were only going to do so much deforestation and we were going to preserve the rest, but because of internal climate and land dynamics somehow we ended up triggering a drying of the Amazon and we ended up losing it not on purpose. That would be pretty awful.

Ariel Conn: Yes. It seems like a good time to get back into tipping points. Can you go into it a little bit more detail about how that works? What is the process there that could push us into a tipping point?

Deborah Lawrence: The person who knows the most about this is Carlos Nobre. He is a Brazilian atmospheric scientist and a brilliant man, and he has worked a lot on this and believes that if we get to the level of, say, 25 to 30% of the Amazon being gone, that we could trigger this warming and drying. So we know that when we clear forest, if you think about it just based on the fact that the trees themselves do all of this evapotranspiration: they have deep roots, they have lots of leaf area, they pull a lot of water out of the soil and put it into the atmosphere. When they are gone, when it's just, say, soy or pasture grasses, they simply don't access the same amount of water. They don't pump the same amount of water into the atmosphere. So during critical times of the year, like during the dry season, there's not as much moisture going into the system.

So it turns out that in Brazil - as I understand it - during the rainy season, they get a lot of moisture from the ocean. But in the dry season, that circulation changes and instead the land relies on recycled water to create whatever rainfall they have. And in fact, to promote the rainy seasons, you actually need to kind of seed the atmosphere with some moisture. So this happens way before all that moisture is delivered from the ocean. And if there's no forest there, you can't seed the atmosphere as well. Little short grasses cannot seed the atmosphere the same way that giant trees can.

What Carlos Nobre says is when we get to a certain amount of the forest gone, we reduce the ability of that forest to seed the atmosphere and we simply dry it out so that that dry season then gets longer. And if it's longer, you can actually hurt the chances of those trees; you can actually stress them out. Maybe they can manage for a certain number of months, but you add two or three months to that and the trees are simply stressed. On top of that, imagine what we'd do with a warmer climate, so that the forests are stressed out by climate change and then in addition we stress them out with this other climate change due to deforestation.

Ariel Conn: Do we have reason to believe that we're getting close to any of these tipping points, or is this something that we're just sort of on the lookout for for right now?

Deborah Lawrence: Well, we are at about 17% of the Amazon gone, and Carlos Nobre thinks that the tipping point could be 25, maybe 30%. That's pretty scary. That seems like it's not too far. So it took us a while to get 17% gone - maybe the last 50 years or so - and it seems like right now we're looking at increasing the rate. It's been low, a low rate of deforestation for a while, but steady. If that rate were to go up, it would mean that we could reach that tipping point faster.

I don't know where we really stand on that. I also don't know that 25% is this perfect number. Some of my work, just reviewing the literature in general, suggests that it could be less of a cliff and more of a slope - maybe that it takes 30, 40, or 50% deforestation to really go over the cliff. So it seems like a safe idea to not get there.

Ariel Conn: That's just for the Amazon, is that correct?

Deborah Lawrence: Correct.

Ariel Conn: Okay. And then you mentioned some other tropical forests. What's going on with those?

Deborah Lawrence: The other big tropical forests are in the Congo Basin, and then centered on Indonesia. It's pretty sad to look at a picture of Indonesia now, because a lot of the forest has gone. So Borneo used to look like a big Amazon. Borneo is about the size of Texas or France; It's a big island, and it's lost a lot of forest. The Congo Basin looks pretty good, but if you kind of zoom in closely, it turns out there's already a lot of pasture and some forest degradation. So it's not the same where you see giant swaths of forest gone, perhaps because they're not as rich or perhaps because they've had a lot of conflict, but really there's threats to rainforests everywhere.

Whether or not these tipping points exist, we don't know. The rainforests in southeast Asia are very different. If you just think about what they look like, it's a bunch of islands in the middle of an ocean; and that is very different from the Amazon, which is like a giant block of forest in the middle of a continent. So you can imagine that some of those tipping points are driven by these drying effects. Well, Borneo has lots of water near it. It's got ocean nearby; it's almost swamped - those water cycling impacts are almost swamped by the fact that there's oceans all around. So it's more like a maritime forest. The Congo is more like the Amazon. Africa is a giant continent. It's a little bit higher than the Amazon. I don't think people have really studied tipping points in the Congo.

Ariel Conn: So there's lots of references to the Amazon being the lungs of the world. I was hoping you could sort of explain what that idea means?

Deborah Lawrence: So first of all, I think it's not an adequate or appropriate metaphor. They are not the lungs of the planet. They're much closer to the sweat glands of the planet - which is also super important, especially in a world that is warming. So the lungs of the planet analogy is that when plants take in carbon dioxide, CO2 plus water becomes a sugar plus oxygen. That's the equation for photosynthesis. So you think, "Aha, oxygen."

So, a couple of problems with that. Some of that oxygen is used immediately after that happened inside the cell to process the sugar that the plant just produced and to feed the plant itself. So half of the carbon dioxide that the Amazon takes up, it's actually using just to exist. And the other half: some of it is stored in wood, some of it is dropped on the forest floor and decomposes. And when it decomposes, it's combining with oxygen again and just going back into the atmosphere as CO2. Some of it is eaten by animals, and if it's eaten by the animal, as soon as it gets inside that animal, it's combined with oxygen and it goes out as CO2.

So really, the only oxygen that is produced by the Amazon is whatever its net uptake is: the stuff that's not used up for the plants or the animals that live there. That's not a huge amount. We have 21% oxygen in the atmosphere, 21%. And that's a really big number. It came from algae, plankton, in vast oceans from, say, two and a half billion years ago. Before there was any atmosphere full of oxygen, there was a bunch of algae that produced a bunch of oxygen. It first was scrubbed out by the atmosphere itself, like it kind of rusted the entire planet. Once it's rusted the entire planet, it finally could build up in the atmosphere.

So really if we're thinking about the lungs of the planet, it was a bunch of algae that existed two and a half billion years ago. It's not the Amazon. It's just not. So I really don't like that analogy, and I think the more important part is the sweat glands of the planet. It's like our brow. Tropical forests keep us cool. They take the hottest solar radiation that we have on the planet, right at the equator, and they use the energy to take liquid water and turn it into vapor - just like the sweat off our brow - and it cools us down.

Ariel Conn: So my understanding is, we have these forests, they absorb carbon - which is great - and if we cut them down, then they're not absorbing the carbon, and so it's going into the atmosphere and warming things. But then my understanding is that, at the same time, when we're cutting down the trees or burning the trees, all the carbon that's in them is also going up. So not only are we not absorbing the carbon, more is emitted into the atmosphere. Is that correct?

Deborah Lawrence: That is exactly right. And it's a double whammy, because the forests sitting there have a huge amount of carbon in them. It's almost equivalent to the reserves of fossil fuels. I think I can check on that, but it's like a huge amount of carbon in all the forests of the world. At the same time, unlike fossil fuels, which are not accumulating lots of carbon every year, the forest do accumulate carbon every year. They take it in and they bury it, part of it below ground and part of it in their trunks.

If we didn't have forests, we would have a much hotter planet. The CO2 that comes out from fossil fuels and from deforestation: of that CO2, half of it gets taken up again by the oceans and the land - so about a fourth in the land and about a fourth in the oceans - leaving only half of what we put into the atmosphere actually remaining in the atmosphere. So that's a huge service the forests and the oceans are doing for us.

Ariel Conn: How much deforestation do you fear could happen? I mean, 100% seems unrealistic. What levels concern you?

Deborah Lawrence: What concerns me is that I think - and again, I might be wrong, you can look it up - I think we've only protected about 15% of the planet. I'm not sure what that number is, but 15% of the forest - that is a bummer. That is really not a lot of forest. What worries me is that if you look at a graph of tropical deforestation, or just deforestation emissions, and you start at 1950, it's really steady. It's always been about a gigaton of carbon every year due to deforestation, and the fossil fuels number has gone from less than one gigaton, now it's at nine gigatons. So it used to be that deforestation was half of our problem. Now it's a 10th of our problem. But it's been so steady. So to me that just says, "Why is it so steady?" We just keep deforesting at this steady rate that gives us one gigaton of carbon every year. It seems like we simply will continue to deforest at this rate, because we have been for decades.

I used to be interested really just in biodiversity. That's what got me into rainforests. And as I became aware of their role in the carbon cycle, I thought, "Oh, this is it. This is the reason we're going to save the rainforest, because it's so important to the entire planet." Somehow the diversity itself, while incredible and wondrous and sustaining in so many ways, it just doesn't seem to resonate the way the climate crisis has resonated - that really we're talking about changing the entire planet. And I thought to myself, "That's going to save the rainforests, because they're so important. They hold so much carbon, they do so much for the climate system." And people have been working on this notion for a while, and it's really hard to figure out how to put the mechanisms in place that can create financial incentives for these countries to save the rainforests so that we can save the climate system.

Ariel Conn: It sounded like it's only just a few crops, really, that are replacing the forest. Is that correct?

Deborah Lawrence: Those are these big ones in big places. I think there's probably people everywhere cutting down for us to just grow anything. Wherever they are, this is how you get new agricultural land. In much of the world, there's still a need for new crop lands, and so I guess the big challenge is that we have 2 billion more people coming and we need to feed them. If we feed them the way we feed ourselves in North America, we're in big trouble, because we really put a strain on the planet. If we can feed people better, if we can do better with our agriculture, if we can produce more food with fewer fossil fuel inputs and less land, we have a chance.

Ariel Conn: You mentioned that the deforestation sort of just keeps continuing at this constant rate. Is it consistent with population growth?

Deborah Lawrence: That's a great question. I don't really know, but part of me feels like, well, it can't be exactly with population growth because we still have hungry people and we also have places where we produce way more crops than we actually eat. So I think there's other dynamics going on, like our ethanol programs, and the fact that some of these crops are used not for food, but for other things. Like, oil palm is a really amazing crop. It can be used in industrial lubricants and it can be in your chocolate bar. It's food, and it's an incredible oil that can be used in all sorts of applications. I just wish it were always planted in places where it was best suited.

Ariel Conn: Are there other places that we could be planting these? The crops that are replacing rainforests - do they actually need that type of climate? Or could they be planted elsewhere?

Deborah Lawrence: I think even in places where it's the same climate - like maybe they do love the tropics, maybe oil palm is born for the tropics - the question is, does it have to go into a brand new, primary, natural, beautiful forest? Or could it go into some degraded area that's already been used for something else? And that something else is some other agriculture that maybe failed or maybe simply was poorly managed. So there is a role for taking existing lands and making better use of them. This is definitely true of the Amazon, where not all of those pastures are just the most efficient, most amazing producers of cattle. Sometimes there's one cow per hectare. I think that's a very low intensity. If there were better management, you could produce more cattle on less land, and that would then free up some of that land either to be forest or to be producing other kinds of food crops.

So degraded land is a great place to look for areas for some of these really important commodities that are globally traded. The other thing is, in Indonesia for instance with oil palm, they tend to go to the peat forests. We haven't really talked about what peat forests are, but they're really interesting swampy forests that have not only a lot of carbon in the above ground - in the trees themselves - but the soil is full of organic matter. It's like a big peat bog, and so it has several meters of carbon rich soil. The only way you can plant oil palm there is to drain it and then to burn off the trees.

And even in that case, it's not like it's great soil. If it were great soil, there would be people growing crops there. But there aren't. The irony is that that's exactly why oil palm companies go to these peat forests: because there's no conflict. What they're really going for is not the land, but the lack of conflict with local people that they might have to make a deal with otherwise. So the reason I bring up the peat is they shouldn't be on peat. They should be on upland forests. Peat has so much more carbon in it. If you're going to put oil palm somewhere, don't put it on a place where there's a bunch of peat. Put on an upland soil that's just a normal mineral soil, because it will grow better, it'll take less work to put in the crop, and it will not release tons and tons of carbon into the atmosphere.

Ariel Conn: I don't know if this is connected: there was an IPCC report that I think came out this summer about the interaction between land and climate. Were there some important takeaways from that that we haven't gotten into yet?

Deborah Lawrence: Yes. So I think one of the important takeaways is that the land really does have an impact on our climate system. So I said earlier that deforestation is only 10% of our anthropogenic CO2. What I didn't say was that agriculture is another chunk. So if you take agriculture and forest together, or basically if you take the land surface and what we do to it, it's about a quarter of all the emissions. If you add to that transportation and processing of food, I think you can get up to a third. So the land is a big player. It's easy to forget, because we think about our energy system and the transformation that needs to occur. It's a huge player, but the land is also really important.

The other point about the land is that it's interactive. So the land itself affects the climate system. And so there are feedbacks, and when we do something to the land system, we also impact the climate system, and then there are feedbacks from the climate system back on the land. There aren't those same kinds of feedbacks when you think about wind turbines or solar panels - it's just not really the same.

The other thing is that anything we can do on the land system to make it more climate friendly - especially things like avoiding deforestation, better forest management, better agricultural management - it all has multiple benefits. Whenever you do something that is good for the forest or good for agriculture, you're feeding more people, you're maintaining biodiversity, you're maintaining flood protections by having intact forests and intact ecosystems. There's really a lot of benefits that accrue when we think about nature's climate solutions on the land.

Oh, and the other thing: the agricultural effects are interesting and somewhat different because they include things like methane and nitrous oxide, which are just different greenhouse gases that we don't always think about. Both of them are really strong greenhouse gases, so they have really quite an important impact on the climate system.

Ariel Conn: I do have a question about that, because we do hear about carbon and trees and plants and whatnot. Do forests do anything with those other greenhouse gases?

Deborah Lawrence: So I'm not sure about nitrous oxide. The natural nitrogen cycle does produce some of those same-nitrogen based greenhouse gases - we have a natural system in place - but the perturbation that humans have done is just dramatic. I think we've probably doubled the amount of nitrogen that's circulating in the atmosphere. I think it's at least doubled. So we've done that by producing fertilizers.

For methane, there's an interesting connection, especially in the tropics. In tropical forests, they produce these things called biogenic volatile organic compounds, BVOCs, and when they produce BVOCs, they go up into the atmosphere and they produce ozone and they prolong the lifetime of methane. So that's actually a bad effect of forests, if you will, because those are greenhouse gases and so they're warming. But the BVOCs also produce these aerosols that are highly reflective, so the BVOCs cool the planet as well - they have high albedo. So BVOCs is are interesting. That is a connection with the methane cycle and with ozone, but it seems to be counterbalanced by the fact that they increase albedo over these forests.

Otherwise, I don't know. People have talked about methane and that forests may produce lots of methane. Well, my question is - I don't really know this literature too well - but I look at the emissions of methane and the concentrations of methane in the atmosphere over the past 2000 years, and it looks to me like it was very steady when the forests existed intact. There was no problem of excess methane when we had forests all over the place. So I don't see why forest methane would be a problem. The methane that I see, the increase in methane in the atmosphere, looks quite clearly related to our use of fossil fuels and our growing of cows. But it's out there. People are interested in whether trees produce methane.

Ariel Conn: Interesting. So we've talked about some of the causes of deforestation and the contribution this has to climate change. What would you like to see policy makers doing, and what would you like to see individuals doing, to help address these issues?

Deborah Lawrence: I would like policymakers to think very hard about how to put a price on carbon, because if you put a price on carbon - and one that is fungible throughout the world - it really will build the case for maintaining those forests because the forests have so much carbon in them. For me, they have so much more than carbon; I think for most people they have a lot more than carbon, but they do have a lot of carbon. So a price on carbon, implemented at an international level, would do so much to incentivize people, local governments, national governments to protect their forests. There's a reason to do it and I'd love to see that.

When I think about what regular old people - individuals like you and me - can do, I would say minimize our impact on the land and minimize our impact on the forest. The way you do that really is by watching what you eat. It's not like Brazil sends us all their meat, but it's part of a global market for beef. I think that those 2 billion people that are coming, really, if they're all going to eat meat like we do, we are in big trouble. We will not have forests left, and we'll have a much warmer planet because of all the methane.

The deforestation that produces beef is really, really the worst to me, because it's got that two-fold effect: first to lose the CO2 from the trees, and then you get a bunch of methane from the cows. So I think our own personal choices around what we eat and the kinds of products that we use. As I said earlier, oil palm is in everything, and there are movements to clean up the supply chain for big commodities. I think if we can be a little bit more aware of what's going into the products we buy, then we might be able to exert some pressure. I think that companies are interested in doing the right thing and consumers are too. So I guess we have to educate ourselves to figure out what's in these products that I buy, what's in my cosmetics, what's in my food, what's in the oil that I put into my car, or whatever it is. It could have a rainforest connection. And the more we're aware of it, I think the more power we have to influence the businesses and the governments that provide us with those products.

I think it's really important to recognize that individual choices alone really will not fix the problem, either for rainforest persistence or for planetary persistence. So the one thing that people can do is vote. People need to vote. They need to start feeling as if climate change, rainforests, the environment, this is something we care about deeply. Partly because we should, because it's just the right thing, but partly because it's our very own future that's at stake. So I want people to vote and be climate voters.

Ariel Conn: Yeah. One of the reasons I wanted to do this this year is to help prep for voters next year. And so a final question for you. What gives you hope?

Deborah Lawrence: What really gives me hope is not just what's going on in the forest. It's hard; it's really hard, especially when you say the Amazon burning. But what gives me hope is that we are tackling climate change. When I look at the energy transformation that I see around me, when I see the rate of uptake of electric vehicles, when I see the amount of solar and wind, it's way faster than anyone thought was possible. So the transition is on. People are changing, with or without action by the United States government. We are moving forward, and I feel very hopeful in that way. I feel like, "Wow, this is way faster than we thought. It's cheaper than we thought. It can only go in one direction." And I feel very heartened by that. I feel like that is happening. It would be better if we had policy that was coherent and strong, but it's happening anyway and that gives me great hope.

The other thing that gives me great hope is that it's a lot of Americans who are concerned about climate change and know about it and believe it. It's like 70%. it's not some fringe radical tree hugging group. It's really everybody. Everybody knows that this is important and that is heartening to me as well. So the real key is to figure out how to push that up in the priorities when people are voting. If they all know about it, they really need to understand that the consequences are great and they have to make it something they vote on.

Ariel Conn: All right. I think that's a really excellent message to end on. Is there anything else that you want to add?

Deborah Lawrence: Doesn't mean you don't do your part. I don't want to let anyone off the hook. Just voting is not enough, because part of what we need is a new normal, and I think the new normal is that we all think about these decisions every day. We turn off the lights, we don't eat a ton of meat. It doesn't mean we eat zero meat - it just means we think about it. There are so many decisions we make every day: do we walk or do we take the bus, or do we drive in our car? Do we go with friends on that trip home from college or do we actually fly home by ourselves?

There's just a million decisions we make, and if we're always thinking about the planet, just a little bit, I think we create this new normal. And then suddenly we're frustrated because we can't do enough. We've done all we can and it turns out we need to do more and we need our government for that. But the new normal says, "We all care about this. We all do everything we can. We also will have your back as elected officials if you do what you can to make our choices that much more effective."

Ariel Conn: All right. That was even better.

Ariel Conn: All right. Well, thank you so much.

On the next episode of Not Cool, a climate podcast, we'll be joined by NOAA's Libby Jewett, who will talk about another topic that I've been excited to get into: the oceans, and especially the problem of ocean acidification.

Libby Jewett: We need to know what impact we're having on the ocean. I mean, the ocean is important, not only because of the seafood that we eat from it, but because it's a driver of larger processes on the earth. And every other breath, they say, that we breathe comes from phytoplankton in the oceans.

Ariel Conn: I hope you enjoyed this episode, and I hope you join us for episode 21 to learn more about ocean acidification. As always, please take a moment to like the podcast, share it and maybe even leave a good review.

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Not Cool Ep 20: Deborah Lawrence on deforestation - Future of Life Institute

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This summer, the world watched in near-universal horror as thousands of square miles of rainforest went up in flames. But what exactly makes forests so precious - and deforestation so costly? On the 20th episode of Not Cool, Ariel explores the many ways in which forests impact the global climate - and the profound price we pay when we destroy them.

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Plant Power: The Power of Plants in a Changing Climate

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Plant Power: The Power of Plants in a Changing Climate

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Welcome to Plant Power: The Power of Plants in a Changing Climate, a new series brought to you by the North Carolina Botanical Garden. Through interviews with some of North Carolina's finest naturalists, explore the conversation about native plants and their connection with our changing climate. Each episode is focused on providing resources to listeners to mitigate climate change impacts in their community. Tune in to our 6 episode mini-series for information on topics like land conservation, protecting our pollinators, and turning to nature as a source of healing.

We want to hear from you! If you listened to the podcast, please take the brief podcast survey. Thank you!

Resources for each episode

Episode 1: Power of Plants Introduction

1. Toward a Theory of Plant Blindness, from Botany.org

2. What's Really Warming the World, from Bloomberg Businessweek

3. The "New Environmental Paradigm", from The Journal of Environmental Education

Episode 2: All that's Green Isn't Good

Episode 3: Climate Resiliency in Seed Collection

1. The contribution of botanic gardens to ex situ conservation through seed banking, from ScienceDirect

2. Good websites to explore: Center for Plant Conservation , Millennium Seed Bank, Svalbard Global Seed Vault

Episode 4: Land Conservation

1. Native Trees and Shrubs for Your Garden, from the North Carolina Botanical Garden

2. Common Trees of the North Carolina Piedmont, from OpenKey

3. available for Apple products on the App Store

4. A Landscape Plan for Wildlife Habitat Connectivity in the Eno River and New Hope Creek Watersheds, North Carolina, from the North Carolina Botanical Garden

5. Duncan, Wilbur H., and Duncan, Marion B. (2000). Trees of the Southeastern United States. University of Georgia Press.

6. Contact your local botanical garden for the best tree ID reference guide for your area

Episode 5: Nature's Role in Healing

Episode 6: Pollinators and Native Ecosystems

1. The Bees of North Carolina: An Identification Guide, from NC State Extension

2. Chatham Mills "Pollinator Paradise" Garden, from NC State Extension

3. Conserving Bees on Farmland, from Michigan State University

4. Native Bee Benefits, from Bryn Mawr College and Rutgers University

Credits

Host & Editor: Emma Wilson
Producer: Janna Starr
Content team: Johnny Randall, Jennifer Peterson, Emma Wilson, Janna Starr
Podcast Artwork: Courtney Starr
Music: Terri Bocklund

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Welcome to Plant Power: The Power of Plants in a Changing Climate, a new series brought to you by the North Carolina Botanical Garden. Through interviews with some of North Carolina's finest naturalists, explore the conversation about native plants and their connection with our changing climate.

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National Geographic | 2017

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Climate 101: Deforestation | National Geographic

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Netflix | 2020

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Our Planet | Forests | FULL EPISODE | Netflix