The Amazon rainforest is undergoing a dramatic transformation, hurtling towards a 'hypertropical' state unlike anything seen in millions of years. This shift, driven by increasingly frequent and intense droughts, poses a significant threat to the planet's climate balance.
A recent study paints a concerning picture: the Amazon is evolving, with conditions that have 'no current analogue.' This means the rainforest is entering uncharted territory, experiencing stresses never before encountered. Trees are struggling, and the forest's ability to absorb carbon dioxide is diminishing. This is based on data collected over three decades across the Amazon, leading researchers to coin the term 'hypertropical' to describe the emerging conditions.
But here's where it gets controversial: these changes are happening now, and the models predict they will become the norm within the next 100 years. Imagine a future where the wet season, typically from December to May, offers no respite from the heat and drought.
The study examined how trees and the soil they live in respond to high temperatures and drought. As these periods intensify, they provide a glimpse into the future. According to geographer Jeff Chambers, the conditions are 'beyond the boundary of what we consider to be tropical forest now.'
As droughts become more common by 2100, trees are predicted to die at an accelerated rate. This is due to reduced soil moisture, which can lead to hydraulic failure, where water transport within trees is blocked, and carbon starvation, where leaf pores close, hindering photosynthesis. Field measurements already show these effects in the current Amazon climate.
If the Amazon becomes hypertropical, these extremes will become much more frequent, potentially increasing the tree mortality rate by 55 percent. Fast-growing trees with low wood density are particularly vulnerable, meaning secondary forests, which have a higher proportion of these trees, may be even more susceptible to drought-induced mortality.
The research focused on two specific Amazon sites affected by the 2015 and 2023 droughts, which were driven by unusually warm El Niño events. The critical water threshold was the same across both sites and years, suggesting a widespread shift. The study predicts that most hypertropical forests will emerge in the Amazon region, but they are also likely to appear in Africa and Asia.
This is a significant shift, as these forests could flip from being carbon sinks to carbon contributors as trees die off. The research underscores the critical role forests play in maintaining atmospheric balance and the devastating consequences of their loss.
'It all depends on what we do,' says Chambers. He emphasizes that the extent to which we create this hypertropical climate depends on our actions regarding greenhouse gas emissions.
What are your thoughts on these findings? Do you think these predictions are realistic? Share your opinions in the comments below!
The research has been published in Nature.
