How Burning trees in Brazil's Amazon melts snow in the Himalayas

Trees set ablaze in Brazil’s Amazon rainforest could contribute to melting glaciers in the Himalayas and Antarctica because distant ecosystems that regulate the Earth’s climate are more closely connected than previously thought. 
 

Scientists have discovered a new atmospheric pathway that originates in the Amazon, runs along the South Atlantic, then across East Africa and the Middle East until it reaches central Asia, according to a paper published this month in Nature Climate Change. That connection, which stretches 20,000 kilometers (12,400 miles) across the globe, means that when the Amazon warms, so does the Tibetan Plateau, whereas the more it rains in the Amazon, the less it rains in Tibet.

The study is among the first to investigate the interaction between ecosystems at risk of reaching a climate tipping point that would transform them irreversibly. More significantly, the newly-discovered pathway suggests that the collapse of one ecosystem could destabilize others too, leading to a cascade of tipping events across the planet.

“Tipping cascades are a risk to be taken seriously,” Hans Joachim Schellnhuber, a researcher at the Potsdam Institute for Climate Impact Research and a co-author of the report, said in a statement. “Inter-linked tipping elements in the Earth system can trigger each other, with potentially severe consequences.”

Scientists are only beginning to investigate the connections between far-flung components of the planet’s climate system. That knowledge is essential to understanding the full impact of global warming, which is caused by greenhouse gas emissions and is already raising sea levels and leading to more severe floods, drought and wildfires on every continent. 

Deforestation in the Amazon, the world’s largest rainforest and home to a quarter of land species, reached its  fastest pace in at least 15 years last year. The southeastern part of the rainforest, which plays a vital role in absorbing planet-warming carbon dioxide from the atmosphere, has become a net source of carbon emissions during the dry season, a 2021 paper concluded. 

The latest report by the UN’s Intergovernmental Panel on Climate Change saw an increased probability that the Amazon will cross a tipping point. The question now is what that might mean for the Himalayas, one of the world’s great reserves of fresh water, which is already seeing unprecedented glacial melt. 

“The Amazon region is of course an important Earth system element by itself,” said Jingfang Fan, a researcher with the Beijing Normal University and the Potsdam Institute. But the research “confirms that Earth system tipping elements are indeed inter-linked even over long distances — and the Amazon is one key example how this could play out.”