Some trees do not save us from global warmingAmy Walsh (Author) Published Date : Feb 07, 2016 11:28 IST
Loss of forests all over the world has led to an increase in maximum and average global temperatures, particularly in tropical and arid regions.
A new study states that forest changes have nudged Europe's summer temperatures up by 0.12 degree Celsius (0.2 Fahrenheit) since 1750, largely because many nations have planted conifers such as pines and spruce whose dark colour traps the sun's heat, the scientists said.
Team led by France's Laboratoire des Sciences du Climat et de l'Environnement stated that evaluating global impact is complicated because deforestation can produce different results in different climate zones, making it hard to determine large-scale trends rather than more local ones.
Overall, the area of Europe's forests has expanded by 10 percent since 1750.
Kim Naudts, lead author of the study, said this leads to less evapotranspiration - the process in which water is transferred from land to the atmosphere by evaporation from the soil and transpiration by plants - and drier air, which had also contributed to warming.
On the other hand, broad-leafed trees with light colors and flat leaves, including birch and oak trees, reflect more sunlight back into space. As Europe expanded its forests to conifers, however, it had to give up its broad-leafed trees.
Fast-growing conifers dominated forests and everything else since then. Conifers stretched to additional 633,000 square kilometers (244,000 miles) of land, while broad-leafed cover was reduced by 436,000 square kilometers (168,000 miles). Thus, the effect took place.
Two and a half centuries of forest management in Europe have not cooled the climate, the team wrote in the journal Science.
They said the changes in the make-up of Europe's forests outweighed trees' role in curbing global warming. Trees absorb carbon dioxide, the main greenhouse gas from burning fossil fuels, from the air as they grow.
Researchers have stated that forest losses amplify the diurnal temperature variation and increase the mean and maximum air temperature, with the largest signal in arid zones, followed by temperate, tropical, and boreal zones. In the decade 2003 2012, variations of forest cover generated a mean biophysical warming on land corresponding to about 18% of the global biogeochemical signal due to CO2 emission from land-use change.
Some trees do not save us from global warming