New research published in the journal Nature reaffirms that key regions of the globe that have been a source of major climate worry to researchers - such as the Amazon rainforest and the forests of the global north - are exquisitely sensitive to swings in climate. And it also identifies some new and similarly vulnerable ecosystems that will bear very close watching.
"Understanding how ecosystems are going to respond to climate variability is an important feature that we still don't have a lot of information on," said Alistair Seddon, the study's lead author and a biologist at the University of Bergen in Norway. "And so what our study is doing is providing that perspective at a global scale." Seddon published the study with researchers from the University of Oxford and the Royal Botanic Gardens at Kew in the UK.
The study did not, as so many papers do, focus on what a long-term warming trend could do to these regions. Rather, it sampled how sensitive they are to climate "variability" - defined in the study as monthly changes in temperature, precipitation or water availability, and cloud cover. Changes in these variables were then compared with satellite imagery of the globe, which captured changes in the greenness of vegetation over the 14-year period from 2000 through 2013.
This approach allowed the researchers to identify Earth ecosystems that responded quite sensitively to changes in climate parameters, as opposed to those that did not - deriving a "vegetation sensitivity index" across the planet. "If there's high variability in temperature, and low variability in vegetation, you're scoring low on the sensitivity index," said Seddon. "That's basically the way it works." A highly sensitive ecosystem, in contrast, changes a lot even in response to slight swings in climate variables.
And that's where the research came up with worrisome results. "We find ecologically sensitive regions with amplified responses to climate variability in the Arctic tundra, parts of the boreal forest belt, the tropical rainforest, alpine regions worldwide, steppe and prairie regions of central Asia and North and South America, the Caatinga deciduous forest in eastern South America, and eastern areas of Australia," the researchers reported.
Some of these regions are already key areas of concern for climate researchers. Take, for instance, the boreal or northern forest. There are fears that Arctic warming will worsen wildfires that, in turn, burn through subsurface layers of soil and hasten the thawing of permafrost beneath. This permafrost, in turn, contains massive amounts of carbon that could potentially be emitted to the atmosphere.