More trees do not make for a cooler planet, according to a new study in the US.
But some experts are concerned that Williams’ work is likely to be misconstrued as permission to continue deforesting, which is not his intention.
It’s widely accepted that our existing forests are vital carbon sinks, and the best course of action is to stop deforestation, while rewilding and reforesting areas already lost.
Deforestation contributes to climate change, can cause wildfires, desertification, soil erosion and most of all – releases huge amounts of carbon dioxide which causes global warming.
But there’s that word – ‘warming’.
WHAT IS ‘THE ALBEDO EFFECT’?
Put simply, ‘the albedo effect’ is the process in which forests retain heat. Forests tend to be darker than other surfaces, which means they absorb more sunlight and hold onto heat, explains Williams.
As a result, some scientists believe that deforestation gets rid of unwanted heat which is contributing to global warming.
“We found that in some parts of the country like the Intermountain West, more forest actually leads to a hotter planet when we consider the full climate impacts from both carbon and albedo effects,” says Professor Williams.
He adds that it is important to consider the albedo effect of forests alongside their well-known carbon storage when aiming to cool the planet.
The research team used state-of-the-art satellite remote sensing to bring an “observational perspective” to a problem that had previously been assessed mostly with computer models.
They pinpointed the locations of forest loss and identified what those sites had become – urban, agricultural, grassland, shrubland, pasture, or something else.
This is how they determined what impact deforestation had on the climate system.
So what did they find? The team discovered that for approximately one quarter of the US, forest loss causes a persistent net cooling because the albedo effect outweighs the carbon effect.
But there was a second factor at play too – location.
“It is all about putting the right trees in the right place,” explains Williams, “and studies like ours can help identify where the potential for cooling is greatest.”
For instance, loss of forests east of the Mississippi River caused planetary warming, while forest loss in the Intermountain and Rocky Mountain West led to a net cooling.
SHOULD WE STOP PLANTING TREES?
Planting trees does a lot of good for the environment, by sequestering carbon in our atmosphere.
But Williams warns that going about planting trees willy nilly could actually have the opposite effect on the planet.
“If we fail to consider both the carbon and the albedo effects, large-scale tree-planting initiatives, such as Canada’s 2Billion Trees Initiative and The Nature Conservancy’s Plant a Billion Trees campaign, could end up placing trees in locations that are counterproductive for cooling the climate system,” he says.
But NGOs such as Cool Earth exist to protect endangered rainforest and work alongside Indigenous communities who call it home. According to the the charity, “we depend upon the rainforest for everything,” it provides us with a fifth of all freshwater and is the best carbon capture and storage technology we have.
“Keeping rainforest standing is the simplest and cheapest way to mitigate climate change,” Cool Earth advocates. It is one of the “most effective actions we can take to tackle climate breakdown.”
For Williams, expanding forest cover cannot be assumed to cool the planet and this is something scientists have known for a while, he says. This has not always been appreciated broadly.
The team at Clark University hopes to continue researching the topic and will help ensure that tree-planting efforts are focused in the right places in future.
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More trees do not always create a cooler planet, study shows
Researchers find some U.S. forests add to global warming
- Date:
- February 12, 2021
- Source:
- Clark University
- Summary:
- New research by an environmental scientist reveals that deforestation in the U.S. does not always cause planetary warming, as is commonly assumed; instead, in some places, it actually cools the planet.
- Share:
New research by Christopher A. Williams, an environmental scientist and professor in Clark University’s Graduate School of Geography, reveals that deforestation in the U.S. does not always cause planetary warming, as is commonly assumed; instead, in some places, it actually cools the planet. A peer-reviewed study by Williams and his team, “Climate Impacts of U.S. Forest Loss Span Net Warming to Net Cooling,” published Feb. 12 in Science Advances. The team’s discovery has important implications for policy and management efforts that are turning to forests to mitigate climate change.
It is well established that forests soak up carbon dioxide from the air and store it in wood and soils, slowing the accumulation of greenhouse gases in the atmosphere; however, that is not their only effect on climate. Forests also tend to be darker than other surfaces, said Professor Williams, causing them to absorb more sunlight and retain heat, a process known as “the albedo effect.”
“We found that in some parts of the country like the Intermountain West, more forest actually leads to a hotter planet when we consider the full climate impacts from both carbon and albedo effects,” said Professor Williams. It is important to consider the albedo effect of forests alongside their well-known carbon storage when aiming to cool the planet, he adds.
The research was funded by two grants from NASA’s Carbon Monitoring System. Williams and his research team — comprising data scientist Huan Gu, Ph.D. from The Climate Corporation and Tong Jiao, Ph.D. — found that for approximately one quarter of the country, forest loss causes a persistent net cooling because the albedo effect outweighs the carbon effect. They also discovered that loss of forests east of the Mississippi River and in Pacific Coast states caused planetary warming, while forest loss in the Intermountain and Rocky Mountain West tended to lead to a net cooling.
According to Professor Williams, scientists have known for some time that expanding forest cover cannot be assumed to cool the planet or to mitigate global warming. However, this has not always been appreciated broadly.
“If we fail to consider both the carbon and the albedo effects, large-scale tree-planting initiatives, such as Canada’s 2Billion Trees Initiative and The Nature Conservancy’s Plant a Billion Trees campaign, could end up placing trees in locations that are counterproductive for cooling the climate system,” said Professor Williams.
“It is all about putting the right trees in the right place,” said Williams, “and studies like ours can help identify where the potential for cooling is greatest.”
Every year, approximately one million acres of forest are being converted to non-forest areas across the lower 48 states of the U.S.; this is largely due to suburban and exurban expansion and development. Professor Williams’ team found that the net climate impact of a full 15 years of forest losses amounts to about 17% of a single year of U.S. fossil fuel emissions.
Williams’ research team used state-of-the-art satellite remote sensing to bring a detailed, observational perspective to examine this problem that had previously been assessed mostly with computer models. The three researchers pinpointed the locations of forest loss and identified what those sites became — urban, agricultural, grassland, shrubland, pasture, or something else. They then quantified how much forest biomass carbon was released to the atmosphere, and how much additional sunlight was reflected out to space. By comparing these two effects they measured the net impact of deforestation on the climate system.
The new datasets and methods used in Professor Williams’ study show that the tools are available to take the albedo effect into account. The Clark team hopes to generate actionable datasets to share with land managers and policymakers worldwide within the next one or two years, to help ensure that their tree-planting efforts focus on the right places and have the intended effects.
Story Source:
Materials provided by Clark University. Note: Content may be edited for style and length.
Journal Reference:
- Christopher A. Williams, Huan Gu, Tong Jiao. Climate impacts of U.S. forest loss span net warming to net cooling. Science Advances, 2021; 7 (7): eaax8859 DOI: 10.1126/sciadv.aax8859
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https://www.rt.com/news/515487-deforestation-can-cool-earth/
Deforestation actually COOLS parts of the US, says bombshell new report from NASA
The bombshell research was led by Christopher A. Williams, an environmental scientist and professor in Clark University’s Graduate School of Geography.
The peer-reviewed study will likely have far-reaching implications for policy and land management efforts across the US and beyond.
Using state-of-the-art satellite remote sensing, as opposed to computer models as was the case in many previous studies, Williams and his team examined what uses various deforested areas were repurposed for (urban, agricultural, grassland etc.) and quantified how much biomass carbon was released into the atmosphere as a result.
They then calculated how much additional sunlight would be reflected back out into space as a result, depending on the particular change in landscape.
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More Trees May Add To Global Warming Than Help Reduce It, Says Study
We often read that to combat climate change and global warming, one needs to planet trees to enable more conversion of carbon dioxide into oxygen and help make the planet colder.
However, now researchers have found that having too much of a dense cover also contributes to more absorption of sunlight which in-turn contributes to the warming of the planet’s temperature. This, according to the researchers is called the ‘albedo effect’.
This is according to a study published in Science Advances. They discovered that for approximately one-fourth of the US, forest loss causes a persistent net cooling because the albedo effect outweighs the carbon effect. They also found that loss of forests near the Mississippi River and on the Pacific Coast have contributed to planetary warming, while forest loss in the Intermountain and Rocky Mountain West has actually contributed to the cooling of the planet.
Researchers used a state-of-the-art satellite remote sensing to populate a detailed, observational perspective in order to examine the issue. Researchers looked at locations of forest loss and find out what those sites turned into — either an urban area, agricultural area, grassland, shrubland pasture etc.
Post this, they quantified the amount of biomass released in the atmosphere and how much sunlight was reflected. Looking at these two effects, they calculated the net impact of deforestation on climate change.
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Related Links:
GOP climate bill will seek to commit US to planting 3.3 billion trees annually
Plant or not plant trees to fight “global warming?! It’s all so confusing! This is what the (allegedly) settled science says:
Christian Science Monitor: Why planting some trees could make global warming worse – 2016
Live Science: Want to Fight Climate Change? Plant 1 Trillion Trees – 2019
Discover Mag: We Can’t Just Plant Billions of Trees to Stop Climate Change – 2019
AP: Best way to fight climate change? Plant a trillion trees – 2019
Climate News Network: Planting trees will not slow global warming – 2017
Update: BBC: Climate change: Planting new forests ‘can do more harm than good’
