The weakening of the Atlantic circulation was called a threat to the Amazon forests

New research show, that the slowing of the Atlantic Meridional Overturning Circulation (AMOC) could lead to severe degradation of the rainforests of the Amazon basin, causing droughts and fires, especially in its northern part.

AMOC is a system of oceanic currents in the Atlantic Ocean that plays an important role in transporting heat to the northern hemisphere and absorbing carbon dioxide. A weakening of this circulation could have catastrophic consequences for the climate not only in Europe, but also in remote regions such as the Amazon, altering precipitation patterns and atmospheric circulation on a global scale.

Led by Tomás Akabane of the University of São Paulo, the scientists investigated the effects of the slowing AMOC on the Amazon rainforest. Using paleoecological analysis of marine sediments, including plant pollen, the researchers reconstructed a picture of climatic conditions in the region 25 to 000 years ago. A sample for the study, taken from a depth of 12 meters off the coast of French Guiana, showed that during the last significant slowdown of the AMOC, about 500 to 2510 years ago, the climate of the Amazon became more seasonal. This caused droughts and increased fire activity in the northern part of the basin, while humidity increased in the southern part.

Modeling using an algorithm MaxEnt demonstrated that in the conditions of modern anthropogenic influence, tropical forests in the north of Amazonia are particularly vulnerable to such changes. They can reach a critical point where forest degradation becomes irreversible, overriding their natural regeneration. Such a transformation could have serious implications for biodiversity and global climate, given the role of the Amazon in carbon sequestration.

In addition to climate change, forests are negatively affected by air pollution. The influence of surface ozone since the beginning of the 20th century got in the way tropical forests to absorb about 21,1 billion tons of carbon, which is a significant factor in the loss of the ability of forests to store carbon.