Deforestation lowers threshold for Amazon degradation to below 2°C warming: report

The change in the South American monsoon could potentially affect weather patterns as far away as the Tibetan Plateau, the statement said.

Mumbai: Around two-thirds of the Amazon rainforest could shift into degraded forest or savannah-like ecosystems at 1.5-1.9°C of global warming if deforestation increases to roughly 22-28 percent of the Amazon, according to a new study from the Potsdam Institute for Climate Impact Research (PIK) published in Nature.

Without additional deforestation, by contrast, such large-scale changes would likely occur only at much higher warming levels of around 3.7–4°C.

The Amazon rainforest is also called the “lungs of the world” for the amount of oxygen its trees produce, and the huge forest drives rainfall patterns across much of South America.

Deforestation weakens the forest’s capacity to generate rainfall, drying out the local atmosphere and causing droughts.

“Deforestation makes the Amazon far less resilient than we previously anticipated. It dries out the atmosphere and weakens the forest’s own rainfall generation. Even moderate additional warming could then trigger cascading impacts across large parts of the forest,” says Nico Wunderling, PIK scientist and lead author of the study.

“Until now, the Amazon rainforest has played a vital role in stabilising the Earth system as a carbon sink, regulator of moisture recycling and host of Earth's richest biodiversity on land. Continued deforestation is undermining this stability, pushing the forest closer to a tipping point. This would not only be devastating for the region, but could have far-reaching consequences for the entire planet,” says Johan Rockström, PIK Director and co-author of the study.

Around 17-18 percent of the Amazon forest has already been lost, placing the system closer to the critical range identified in the study, a PIK press statement said.

This loss of rainfall would have massive impacts on agricultural land from southern Brazil, Bolivia, and Paraguay down to the Rio de la Plata basin in Argentina, potentially threatening crop yields and regional water security. Brazil, Columbia, Ecuador, Bolivia, and Peru gain 70 per cent of their GNP from agribusiness, hydropower, and heavy industry, all of which would be heavily affected by a reduction in rainfall. Drought would also affect inland fisheries, and there would also be a local increase in heat dangerous to humans and a huge uptick in wildfires, causing acute crises and massive air pollution.

The change in the South American monsoon could potentially affect weather patterns as far away as the Tibetan Plateau, it said.

Professor Carlos Nobre, a pioneer in the field who was one of the first to warn of a possible Amazon “tipping point”, called this a “very important study.”

Prof. Nobre, who was not involved in this new paper in Nature, said:“Deforestation has reached 17%-18% of the Amazon forest and global warming is about to reach 1.5 C warming by 2030. It is essential to implement nature-based solutions to save the Amazon forest: zero deforestation, degradation and man-made fires by 2030, and large-scale forest restoration in the Amazon, especially the southern area that has the highest deforestation and the dry season is 4-5 weeks lengthier in the last 40-45 years and up to 20% drier.”