Nov 7, 2024 10:12 PM
https://www.eurekalert.org/news-releases/1063652
INTRO: Tree planting has been widely touted as a cost-effective way of reducing global warming, due to trees’ ability to store large quantities of carbon from the atmosphere. But, writing in the journal Nature Geoscience, an international group of scientists argue that tree planting at high latitudes will accelerate, rather than decelerate, global warming.
As the climate continues to warm, trees can be planted further and further north, and large-scale tree-planting projects in the Arctic have been championed by governments and corporations as a way to mitigate the worst effects of climate change.
However, when trees are planted in the wrong places - such as normally treeless tundra and mires, as well as large areas of the boreal forest with relatively open tree canopies - they can make global warming worse.
According to lead author Assistant Professor Jeppe Kristensen from Aarhus University in Denmark, the unique characteristics of Arctic and sub-Arctic ecosystems make them poorly suited for tree planting for climate mitigation.
“Soils in the Arctic store more carbon than all vegetation on Earth,” said Kristensen. “These soils are vulnerable to disturbances, such as cultivation for forestry or agriculture, but also the penetration of tree roots. The semi-continuous daylight during the spring and early summer, when snow is still on the ground, also makes the energy balance in this region extremely sensitive to surface darkening, since green and brown trees will soak up more heat from the sun than white snow.”
In addition, the regions surrounding the North Pole in North America, Asia and Scandinavia are prone to natural disturbances - such as wildfires and droughts - that kill off vegetation. Climate change makes these disturbances both more frequent and more severe.
“This is a risky place to be a tree, particularly as part of a homogeneous plantation that is more vulnerable to such disturbances,” said Kristensen. “The carbon stored in these trees risks fueling disturbances and getting released back to the atmosphere within a few decades.”
The researchers say that tree planting at high latitudes is a prime example of a climate solution with a desired effect in one context but the opposite effect in another.
“The climate debate is very carbon-focused, because the main way humans have modified the Earth’s climate in the last century is through emitting greenhouse gases from burning fossil fuels,” said Kristensen. “But at the core, climate change is the result of how much solar energy entering the atmosphere stays, and how much leaves again – Earth’s so-called energy balance.” (MORE - details, no ads)
INTRO: Tree planting has been widely touted as a cost-effective way of reducing global warming, due to trees’ ability to store large quantities of carbon from the atmosphere. But, writing in the journal Nature Geoscience, an international group of scientists argue that tree planting at high latitudes will accelerate, rather than decelerate, global warming.
As the climate continues to warm, trees can be planted further and further north, and large-scale tree-planting projects in the Arctic have been championed by governments and corporations as a way to mitigate the worst effects of climate change.
However, when trees are planted in the wrong places - such as normally treeless tundra and mires, as well as large areas of the boreal forest with relatively open tree canopies - they can make global warming worse.
According to lead author Assistant Professor Jeppe Kristensen from Aarhus University in Denmark, the unique characteristics of Arctic and sub-Arctic ecosystems make them poorly suited for tree planting for climate mitigation.
“Soils in the Arctic store more carbon than all vegetation on Earth,” said Kristensen. “These soils are vulnerable to disturbances, such as cultivation for forestry or agriculture, but also the penetration of tree roots. The semi-continuous daylight during the spring and early summer, when snow is still on the ground, also makes the energy balance in this region extremely sensitive to surface darkening, since green and brown trees will soak up more heat from the sun than white snow.”
In addition, the regions surrounding the North Pole in North America, Asia and Scandinavia are prone to natural disturbances - such as wildfires and droughts - that kill off vegetation. Climate change makes these disturbances both more frequent and more severe.
“This is a risky place to be a tree, particularly as part of a homogeneous plantation that is more vulnerable to such disturbances,” said Kristensen. “The carbon stored in these trees risks fueling disturbances and getting released back to the atmosphere within a few decades.”
The researchers say that tree planting at high latitudes is a prime example of a climate solution with a desired effect in one context but the opposite effect in another.
“The climate debate is very carbon-focused, because the main way humans have modified the Earth’s climate in the last century is through emitting greenhouse gases from burning fossil fuels,” said Kristensen. “But at the core, climate change is the result of how much solar energy entering the atmosphere stays, and how much leaves again – Earth’s so-called energy balance.” (MORE - details, no ads)