In 2005, a massive drought struck the Amazon--the largest, most verdant and vital rainforest on the planet. A full 270,000 square miles of old growth forest were wracked by severe drought. Trees died, branches fell off, canopies withered. It led to devastating short-term impacts on one of the world's most complicated, life-stuffed on-land ecosystems.
But scientists were confident that the forest would bounce back to normal before long, that the world's thickest forest would prove resilient to warming climes. They were wrong.
A new NASA analysis of satellite data reveals that an area of the Amazon twice the size of California has continued to suffer fallout from the 2005 mega-drought, right up through the next severe regional water shortage, which hit in 2010. In other words, the Amazon had not yet recovered from the first mega-drought when the second one hit just five years later. Now, scientists are concerned that if climate change-fueled droughts recur every 5-10 years, as has been the recent trend, the Amazon may never recover.
Sassan Saatchi, a scientist with NASA's Jet Propulsion Laboratory, led the research team.
"Our results suggest that if droughts continue at five- to 10-year intervals or increase in frequency due to climate change, large areas of the Amazon forest are likely to be exposed to persistent effects of droughts and corresponding slow forest recovery," he said in a release. "This may alter the structure and function of Amazonian rainforest ecosystems."
Yadvinder Malhi, a researcher from Oxford, agrees: "The biggest surprise for us was that the effects appeared to persist for years after the 2005 drought. We had expected the forest canopy to bounce back after a year with a new flush of leaf growth, but the damage appeared to persist right up to the subsequent drought in 2010." In the following heat map, you can see the damage for yourself:
Which means, of course, that the fallout of the 2010 megadrought is still continuing today. But how much of this can be chalked up to climate change? Saatchi says that, "In effect, the same climate phenomenon that helped form hurricanes Katrina and Rita along U.S. southern coasts in 2005 also likely caused the severe drought in southwest Amazonia. An extreme climate event caused the drought, which subsequently damaged the Amazonian trees."
Which is, of course, bad news for the Amazon. The rainforest, which also happens to be one of the most important carbon sinks in the world, is already busy staving off aggressive deforestation. Clear-cutting is still rampant thanks to the lucrative cattle trade, farming, the demand for timber, and a black market that facilitates exploitation. Worse, as Amazon residents leave their rural homes for the city, there are fewer safeguards against illegal activity and wildfires. Urbanization, it has been said, has left the Amazon burning.
And now recurring megadroughts are drying it up from the inside out. This NASA analysis can be thought of as a sort of 'stage one' of global warming's grip on the rainforest, how the end begins. A study published in Nature Geoscience three years ago found that even modest temperature rises could kill between 20-40% of the Amazon's trees. A rise of 4 degrees Celsius, meanwhile, would wipe out 85% of the entire rainforest.
To prevent that level of warming, some scientists now think that we'll have to reduce emissions to "near-zero" by 2060. Which means we should begin to explore and imagine the above near-future scenarios more comprehensively, because it is entirely plausible they may unfold within our lifetime. We allow images of the melting Arctic to punch us in the gut--now it's time to do the same with a vision of a desiccating rainforest.