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Warming Arctic Mitigates Global Warming

Warming at the Arctic has increased vegetation growth that can, in turn, slow down global warming.

The Arctic 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 Arctic, 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 Arctic,” said lead author Piao Shilong, professor at the Institute of Tibetan Plateau Research (ITP) of the Chinese Academy of Sciences (CAS).

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 on Earth. Using long-term satellite records, they observed significant global greening of vegetated areas since the 1980s, which recent data suggest has continued past 2010.

It is still too early to tell if this greening will have an overall positive outcome, however. The study warned that while greening was found to mitigate global warming through enhanced land carbon uptake and evaporative cooling, it might also lead to decreased albedo that could potentially cause local warming. Furthermore, 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.

“The greening of the Arctic 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 Arctic through evaporative cooling, and induce a remote effect on downstream Asian climate. But the quantification of this teleconnection needs exploration in the future.” [APBN]

Source: Piao, S. et al. (2019). Plant phenology and global climate change: Current progresses and challenges. Global change biology25(6), 1922-1940.