The Amazon Rainforest May Be in Trouble

News about climate change has been pushed into the background for a while because of the pandemic and the war in Ukraine. But it's not going away and some of the news is not good.

We've known for some time the Amazon rainforest is in serious trouble, with deforestation destroying more and more of the forest. Now a new study suggests that the rainforest is losing it's ability to recover from external stresses like drought, not to mention the impacts of human settlement.

A paper published today in the journal Nature Climate Change aims to provide more clarity on that tipping point, which may be rapidly approaching. While prior research used complicated modeling to predict how the decline might unfold, this new research is based on satellite data that shows 75 percent of the Amazon has become less resilient to disturbances like drought.

For a forest, one way to track resiliency is through a satellite measurement called vegetation optical depth, or VOD, which penetrates through the canopy and detects how much woody biomass there is. (Other satellite techniques just look at the tops of trees, but VOD gets a better picture of what’s hidden underneath.) These scientists also looked at a separate data set tracking changes in types of land cover—for instance, forest versus farms—which allowed them to pick out where urban areas and croplands have intruded on the rainforest. Because they had data going back to 1991, they could watch how long it took for a given plot of the Amazon to recover by growing its biomass back after a disturbance. This regrowth is resilience.

And the Amazon is losing it. The researchers broke the rainforest up into an imaginary grid, allowing them to keep track of vegetation within the cells and to correlate that with stressors like droughts or nearby land development. 

They found that the vegetation in over three-quarters of the Amazon has been losing resilience since the early 2000s—a slower rate of return to normal after disruptions. Because the researchers also had that land-cover data, they could further show that areas that receive less rainfall or are closer to human disturbances, like farmland, are losing resilience faster than wetter, unsullied land.