The Third Pole has seen an increase in vegetation over the past three decades. This phenomenon, also known as "greening," may help slow rapid local warming, according to an invited review paper published in the inaugural issue of Nature Reviews Earth & Environment.
The review finds that CO2 fertilization is the main driver of greening on the global scale. However, in places with a lighter human footprint, such as the Third Pole, global warming is the main cause of greening. "This greening is likely to persist well into the future, because the optimum air temperature for ecosystem productivity is still well below the present-day growing-season air temperature at the Third Pole," said lead author PIAO Shilong, professor at the Institute of Tibetan Plateau Research (ITP) of the Chinese Academy of Sciences (CAS).
Prof. PIAO was invited to lead this comprehensive review of global vegetation change and its climate feedback covering the period from the 1980s to the present. Studying biosphere changes and their impacts is crucial for understanding and adapting to the dramatic changes taking place in the Earth system.
"The greening of the Third Pole has both local and remote impacts on climate change," said PIAO, noting that such vegetation growth may contribute to a slowdown of rapid local warming.
"It would also modify the atmospheric heat source of the Third Pole through evaporative cooling, and induce a remote effect on downstream Asian climate," said PIAO. "But the quantification of this teleconnection needs exploration in the future."
It is still too early to tell if this greening will have an overall positive outcome, though. Another study by PIAO’s team has found that warming-induced earlier greening may induce more water loss through enhanced evapotranspiration. This would create drier summer soils across the northern hemisphere, which might result in more frequent heat waves.
These studies are supported by the Second Tibetan Plateau Expedition and Research (STEP), a TPE-related scientific project.
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