Plant a tree and save the planet? Let's think again.
Via Eurekalert, Atmospheric Science. It has become fashionable for organisations, companies and individuals to engage in 'feel good' strategies to reduce their 'carbon footprint' and to confess their 'CO2 guilt'. One of these strategies has been to green-up by planting trees. This carbon-offsetting strategy has become a bit of a commerce, with companies and NGOs selling certificates proving you have contributed to reducing climate change voluntarily by planting a tree somewhere (an overview and introduction of the commerce: "feel free to buy a tree, so you can keep driving your gas guzzling SUV"). This consumerist, individualist and fashionable approach to tackling climate change may be dangerous because it doesn't tackle any problem in a structural way. Moreover, it is not really based on science.
Let's start with a simple question: can planting trees really stop sea levels from rising, the ice caps from melting and hurricanes from intensifying as some carbon offsetting commerçants claim? A new study shows that this is most often not the case, and it cautions that new forests in mid- to high-latitude locations could actually create a net warming. The study does confirm the notion that planting more trees in tropical rainforests could help slow global warming worldwide. Several scientists studying different forest types earlier found very conflicting results, with some forest types showing a net warming effect, whereas other types may mitigate climate change (earlier post).
The new study is the first to investigate the combined climate and carbon-cycle effects of large-scale deforestation in a fully interactive three-dimensional climate-carbon model, scientists from the Université de Montpellier II, Lawrence Livermore National Laboratory, and the Carnegie Institution found that global forests actually produce a net warming of the planet.
The study provides a holistic view of the deforestation issue. “This is the first comprehensive assessment of the deforestation problem” says Govindasamy Bala, lead author of the research that will be presented on Dec. 15 at the American Geophysical Society annual meeting in San Francisco. The models calculated the carbon/climate interactions and took into account the physical climate effect and the partitioning of the carbon dioxide release from deforestation among land, atmosphere and ocean.
biomass :: bioenergy :: biofuels :: energy :: sustainability :: carbon dioxide :: albedo effect :: evaporation :: climate change :: global warming :: forests :: rainforests ::
“The darkening of the surface by new forest canopies in the high latitude Boreal regions allows absorption of more sunlight that helps to warm the surface. In fact, planting more trees in high latitudes could be counterproductive from a climate perspective,” Bala said.
The study finds little or no climate benefit when trees are planted in temperate regions.
“Our integrated systems approach allowed us for the first time to estimate the total effects of land cover change in different regions of the world,” Bala said.
Not feel-good initiatives, but changing our energy system
Afforestation has been promoted heavily in mid-latitudes as a means of mitigating climate change. However, the combined carbon/climate modeling study shows that it doesn't work. The albedo effect (the process by which less sunlight is reflected and more is absorbed by forest canopies, heating the surface) cancels out the positive effects from the trees taking in carbon.
“To prevent climate change, we need to transform our energy system. It is only by transforming our energy system and preserving natural habitat, such as forests, that we can maintain a healthy environment. To prevent climate change, we must focus on effective strategies and not just ‘feel-good’ strategies.”
Let's start with a simple question: can planting trees really stop sea levels from rising, the ice caps from melting and hurricanes from intensifying as some carbon offsetting commerçants claim? A new study shows that this is most often not the case, and it cautions that new forests in mid- to high-latitude locations could actually create a net warming. The study does confirm the notion that planting more trees in tropical rainforests could help slow global warming worldwide. Several scientists studying different forest types earlier found very conflicting results, with some forest types showing a net warming effect, whereas other types may mitigate climate change (earlier post).
The new study is the first to investigate the combined climate and carbon-cycle effects of large-scale deforestation in a fully interactive three-dimensional climate-carbon model, scientists from the Université de Montpellier II, Lawrence Livermore National Laboratory, and the Carnegie Institution found that global forests actually produce a net warming of the planet.
The study provides a holistic view of the deforestation issue. “This is the first comprehensive assessment of the deforestation problem” says Govindasamy Bala, lead author of the research that will be presented on Dec. 15 at the American Geophysical Society annual meeting in San Francisco. The models calculated the carbon/climate interactions and took into account the physical climate effect and the partitioning of the carbon dioxide release from deforestation among land, atmosphere and ocean.
“Our study shows that preserving and restoring forests is likely to be climatically ineffective as an approach to slow global warming” - Ken Caldeira, co-author of the study from the Carnegie Institution.Forests affect climate in three different ways:
- they absorb the greenhouse gas carbon dioxide from the atmosphere and help to keep the planet cool;
- they evaporate water to the atmosphere and increase cloudiness, which also helps keep the planet cool;
- and they are dark and absorb a lot of sunlight, warming the Earth.
biomass :: bioenergy :: biofuels :: energy :: sustainability :: carbon dioxide :: albedo effect :: evaporation :: climate change :: global warming :: forests :: rainforests ::
“The darkening of the surface by new forest canopies in the high latitude Boreal regions allows absorption of more sunlight that helps to warm the surface. In fact, planting more trees in high latitudes could be counterproductive from a climate perspective,” Bala said.
The study finds little or no climate benefit when trees are planted in temperate regions.
“Our integrated systems approach allowed us for the first time to estimate the total effects of land cover change in different regions of the world,” Bala said.
Not feel-good initiatives, but changing our energy system
Afforestation has been promoted heavily in mid-latitudes as a means of mitigating climate change. However, the combined carbon/climate modeling study shows that it doesn't work. The albedo effect (the process by which less sunlight is reflected and more is absorbed by forest canopies, heating the surface) cancels out the positive effects from the trees taking in carbon.
“To prevent climate change, we need to transform our energy system. It is only by transforming our energy system and preserving natural habitat, such as forests, that we can maintain a healthy environment. To prevent climate change, we must focus on effective strategies and not just ‘feel-good’ strategies.”
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