Science: A cloudy future for the Amazon

[Robin Collins]

A cloudy future for the Amazon

Deforestation practices such as logging can increase cloud cover, which reduces warming by reflecting sunlight.  RICH CAREY/GETTY IMAGES.

Deforestation in the Amazon isn’t just disruptive for local plants and animals; it’s also disruptive for the planet at large. Burning plant matter adds carbon to the atmosphere directly, but there are also indirect changes—to the amount of sunlight reflected back to space, the composition of the atmosphere, and even the formation of clouds—any of which can mediate or stoke global warming. To begin to understand the broader impacts of deforestation, researchers analyzed 2 decades of satellite observations to compare cloud cover over areas that had and had not been deforested. They found a clear trend: Cloud cover increases with more deforestation, with the most cleared areas seeing 5% more cloud cover. Clouds were also lower in deforested areas compared to intact ones—a positive note for the climate, since low clouds reflect more of the sun’s radiation than they trap. However, the study shouldn’t be seen as a hall pass for continued forest loss, not least because the atmospheric effects of aerosols from burning are unclear. “Notably, there is no indication that the net biophysical effect of Amazon deforestation will completely offset the warming, even with the cloud changes,” explained atmospheric scientist Gunnar Myhre in a related Perspective. “It is important to maintain and restore Amazon forest cover for mitigating climate change and sustaining critical ecosystems.”

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