Climate-affected evolution

Dear EarthTalk: Could global warming really be a factor in the evolution of wildlife species?


Camden, N.J.


No doubt the quickly changing climate is already triggering various evolutionary shifts in a wide range of species. And while we can’t be sure just how different wildlife species will adapt (or not), scientists are already noticing some surprising changes as a result of rising surface and ocean temperatures thanks to human-induced global warming. 

To wit, a recent study published in the peer-reviewed scientific journal Global Change Biology by scientists from the University of British Columbia found that the body size of larger fish species decreases 20 to 30 percent for every one-degree-Celsius increase in water temperature, given their gills’ inability to keep up in our warmer and increasingly oxygen-deprived seas. (The top 2,000 feet of the ocean water column has warmed 0.3 degrees Fahrenheit since 1969, and the speed of the warming is faster than ever.) 

The result could be a profound shift in marine food webs, with untold consequences for the health of the ocean, not to mention the state of our dinner plates (nearly a billion people around the world rely on fish as a primary source of protein).

And there’s proof that global warming is shrinking wildlife species on land, too. An October 2014 study by scientists at Durham University in Britain found that chamois mountain goats in the Italian Alps weigh 25 percent less than their same-age counterparts did 30 years ago. 

University of Maryland researchers found that six out of seven species of U.S. salamanders studied have shrunk an average of eight percent overall since the 1950s. 

A February 2017 review of scientific literature on global warming’s broad footprint on wildlife by 17 researchers collaborating from around the world revealed that 47 percent of land mammals and 23 percent of birds — more than 700 wildlife species overall — have already been affected by global warming. 

“We need to greatly improve assessments of the impacts of climate change on species right now,” says University of Queensland researcher and study co-author James Watson. “We need to communicate this to wider public. Climate change is not a future threat any more.”


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