Combined biogeophysical and biogeochemical effects of large-scale forest cover changes in the MPI earth system model
Combined biogeophysical and biogeochemical effects of large-scale forest cover changes in the MPI earth system model
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DOI：
10.5194/bg-7-1383-2010
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发表时间：
2010-01-01
期刊：
影响因子：
4.9
通讯作者：
Gayler, V.
中科院分区：
文献类型：
--
作者：
Bathiany, S.;Claussen, M.;Gayler, V.
造林和再造林已成为减缓气候变化政策的常用手段，因为森林储存了大量的碳。然而，它们也改变了陆地表面的能量、水和动量的通量。以前的研究表明，这些生物地球物理效应可以抵消碳的减少，在北方纬度地区，由于森林冠层和积雪之间的反照率差异很大，甚至可以过度补偿碳的减少。本研究利用马克斯·普朗克气象研究所（MPI-ESM）的地球系统模型进行了毁林和造林实验，探讨了森林覆盖对全球气候的作用。热带地区（18.75°S-15°N）的完全毁林会造成0.4°C的全球变暖，原因是毁林地区的二氧化碳浓度最初增加60 ppm，并且蒸发蒸腾减少。在北纬地区（45°N-90°N），完全砍伐森林会在100年后使全球降温0.25℃，而植树造林则会导致同样大的升温，尽管二氧化碳浓度的变化起到了抵消作用。这些发现定性地证实了早期的模型研究。由于温度和陆地碳库的响应在每个陆地单元中都不是等号的，因此考虑森林在热带地区变冷而在高纬度地区变暖似乎只在空间平均上是正确的，而不是在局部尺度上。
Afforestation and reforestation have become popular instruments of climate mitigation policy, as forests are known to store large quantities of carbon. However, they also modify the fluxes of energy, water and momentum at the land surface. Previous studies have shown that these biogeophysical effects can counteract the carbon drawdown and, in boreal latitudes, even overcompensate it due to large albedo differences between forest canopy and snow. This study investigates the role forest cover plays for global climate by conducting deforestation and afforestation experiments with the earth system model of the Max Planck Institute for Meteorology (MPI-ESM). Complete deforestation of the tropics (18.75 degrees S-15 degrees N) exerts a global warming of 0.4 degrees C due to an increase in CO2 concentration by initially 60 ppm and a decrease in evapotranspiration in the deforested areas. In the northern latitudes (45 degrees N-90 degrees N), complete deforestation exerts a global cooling of 0.25 degrees C after 100 years, while afforestation leads to an equally large warming, despite the counteracting changes in CO2 concentration. Earlier model studies are qualitatively confirmed by these findings. As the response of temperature as well as terrestrial carbon pools is not of equal sign at every land cell, considering forests as cooling in the tropics and warming in high latitudes seems to be true only for the spatial mean, but not on a local scale.