Because tropical species trap a lot of carbon when they grow, the loss of parts of the rainforest would reduce the world`s ability to absorb human greenhouse gas emissions. But even before the problem reaches this point, longer periods of drought could have serious consequences for the climate. Even a partial loss of the rainforest would significantly increase the carbon content of the atmosphere, say the authors, with consequences on the climate. The tipping point is like a climate border beyond which conditions would be too dry to survive rain forest species. Once crossed, the rainforest would die and be replaced by other habitats such as seasonal forests and savannahs. Image caption The Amazon rainforest is on fire in August 2019 near the town of Porto Velho in the state of Rondénia. Image by Victor Moriyama / Greenpeace. Overall, scientists know that rainforests are resistant to a certain level of climate change. But a prolonged period of drought is particularly problematic for trees in areas where conditions are wet enough to survive tropical forests. As on the southern periphery of the Amazon. New research shows that since 1979, the dry season in the southern parts of the Amazon rainforest has increased by about seven days per decade. The authors cannot really link the changes to a single factor, but they say that the trend they have observed is similar to the effects of climate change. Another concern is that by allowing the richest countries to “compensate” for their pollution from emissions reductions elsewhere, the result will be that emissions from all fossil fuels will simply not fall fast enough to prevent climate change from happening.
In the long run, this should also be catastrophic for tropical forests. According to climate models, the Amazon basin will experience some of the largest temperature increases. Changes are already being observed in local weather conditions, with warmer and drier climates. It is not clear whether tropical forests can withstand such changes that could occur in a few decades. Forest fires are probably more frequent. The increase in Amazon rainforest fires in August highlighted how Brazil is moving in the opposite direction to its climate change targets, including zero illegal deforestation by 2030. In addition to man-made deforestation and degradation, global warming itself reduces the ability of the Amazon rainforest to store carbon in organic matter, especially in soils. According to a study by Brazil`s National Research Institute in the Amazon State (INPA), soil carbon is decreasing in “undisturbed” Amazonian forests near Manaus, Brazil.