Climate change is not simply a matter of cause and effect. It’s more like a vicious circle. Thomas Crowther is a professor at ETH Zürich, a university in Switzerland.

Crowther: “Not only are we directly altering the climate, but that process in itself is kicking off these things that are gonna actually accelerate the damaging impacts over the rest of the century.”

This self-reinforcing cycle is called a feedback loop. For example, warmer temperatures make soil microbes more active. The microbes then release more carbon into the atmosphere – which in turn speeds up global warming, which makes the microbes even more active, and so on.

Crowther: “I just imagine a sort of wheel spiraling out of control.”

Melting sea ice is another example. Because ice is white, it reflects sunlight back to outer space, which reduces the heat absorbed by the earth. But global warming melts the ice, leaving dark ocean water behind. The water then absorbs the sun’s heat, which increases global warming … leading to more melting ice.

Crowther says it’s hard to predict just how much these feedback loops will speed up the pace of global warming, so they represent a worrisome unknown.

Reporting credit: Daisy Simmons/ChavoBart Digital Media.
Photo credit: NASA Goddard Space Flight Center.