Dried Out Amazon Could Speed Up Climate Change

A new NASA-funded study has found that a dried out Amazon, which has experienced a decline in rainfall over the last decade, could speed up global climate change due to the subsequent drop in vegetation.

And global climate models predict that things are only going to get more arid for the region in the future.

The Amazon's tropical rainforests are one of the largest sinks for atmospheric carbon dioxide (CO2) on the planet. They store an estimated 120 billion tons of Earth's carbon - that's about three times more carbon than humans release into the atmosphere each year. But without an abundance of green leafy vegetation to soak up this greenhouse gas, the consequences could be catastrophic.

"In other words, if greenness declines, this is an indication that less carbon will be removed from the atmosphere. The carbon storage of the Amazon basin is huge, and losing the ability to take up as much carbon could have global implications for climate change," lead author Thomas Hilker at Oregon State University said in a news release.

Using NASA satellites, researchers measured the "greenness" of plants and trees. They were astonished to find that rainfall had declined up to 25 percent across two thirds of the Amazon from 2000 to 2012, and consequentially the rainforest suffered a 0.8 percent decline in greenness, or vegetation. And while the lack of vegetation may seem miniscule, it affected a whopping 2.1 million square miles (5.4 million square kilometers) of the Amazon - that's over half the area of the continental United States.

In the past, scientists have had a difficult time using satellites to measure changes in vegetation greenness over the Amazon because cloud cover prevents the remote sensors from observing the surface.