Climate change causes unequal problems: Every part of the world is being affected, but some places are changing faster, and may be closer to the tipping point of ecological collapse.
A new study mapped out where nature is most sensitive to one aspect of a changing climate—big swings in rain, cloud cover, and heat.
"A big question we face for understanding how ecosystems respond to a change in climate is how they respond to climate variability," says Alistair Seddon, lead author of the study and a biologist at the University of Bergen in Norway. "So we asked a simple question—which ecosystems respond to climate variability."
Looking at 14 years of satellite data from NASA, month by month, the team mapped out how plants and trees changed along with the weather. Their new tool, called the "vegetation sensitivity index," is something that couldn't have existed before. "Previously we've not had enough data available to get a global picture—definitely not in remote locations," he says. "We've just had scattered observations in such areas."
In the past, researchers have looked at fewer details—like how much average rainfall in a year affects vegetation—and they've tried to create models of what might happen in the future. But the new satellite mapping technique can create a clearer picture of what's already going on because of extreme weather.
Places like the Amazon rainforest and the Arctic tundra are especially sensitive to changes in the climate, along with grasslands in North America, alpine regions around the world, and eastern Australia. On the map, the areas in red are most sensitive; green regions are more resilient.
"I think that one of the interesting things is that areas that have been shown to be sensitive to other dimensions of climate change—e.g. rapid warming and rapid ecosystem response in the Arctic—also showed high sensitivity to variability," says Seddon.
Knowing which places are most sensitive to swings in climate is a step in knowing where to prioritize; the more unstable an ecosystem is, the likelier it may be close to collapse. "Ecosystems are likely going to have to face multiple dimensions of climate change in the future ... and understanding how they will respond to variability is a key knowledge gap," he says. The next step is figuring out why some places are so likely to change so fast.