The Amazon rainforest has been drying up for the last 13 years, and with more drying predicted as global temperatures rise, that could spell long term disaster, not only for the world's largest rainforest, but also for the global climate, a new NASA study finds.

NASA satellites utilized in the study analyzed 13 years of rainfall amounts and the "greenness" of vegetation inthe world's largest rainforest. That analysis found that rainfall amounts in the rainforest dropped by up to 25 percent from 2000 to 2012 and that the greenness of 2.1 million square miles of vegetation declined by 0.8 percent during the same time period.

A decrease in the greenness of vegetation is important, no matter how small, because it signals that plants aren't as healthy and can't suck up as much carbon dioxide from the atmosphere.

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It's even more important in the Amazon, which is one of the largest carbon stores on Earth. As NASA points out, the Amazon houses 120 billion tons of carbon, around three times what humans emit on a yearly basis.

"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," the study's lead author, Thomas Hilker, said in a NASA press release.

That effect is only amplified by a decline in total rainfall. The impact of less rainfall seems obvious: Without rain, vegetation struggles to grow. But previous studies on drought and the Amazon show that the rainforest is particularly sensitive to a lack of rain.

A severe drought in 2005 actually killed off so many trees that areas of the Amazon started to release carbon into the atmosphere instead of absorbing it, Science reports.

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The Amazon experiences pronounced wet and dry seasons that are amplified by changes in Pacific Ocean surface temperatures, which drive storms toward the rainforest, NASA reports.

Scientists expect that, in the future, climate change could cause more dramatic changes in those ocean temperatures, according to Climate Central.

That would mean more intense droughts for the Amazon, increased drying, decreased greenness and less carbon storage, meaning more human carbon emissions would end up in the atmosphere and accelerate the impacts of anthropogenic climate change. (And none of that even takes into the account the environmental impact that mass deforestation is having on the Amazon, seen in the animation above.)

"…if, as global circulation models suggest, drying continues, our results provide evidence that this could degrade the Amazonian forest canopies, which would have cascading effects on global carbon and climate dynamics," Hilker said.

MORE ON WEATHER.COM: Alaska's Disappearing Glaciers

Muir Glacier and Inlet (1895)

In the photo above, the west shoreline of Muir Inlet in Alaska's Glacier Bay National Park & Preserve is shown as it appeared in 1895. Notice the lack of vegetation on the slopes of the mountains, and the glacier that stands more than 300 feet high. See the glacier as it looked in 2005 on the next page. (USGS/Bruce Molnia)