The Heat Is On A Bugs Life Too

Bugs are facing a changed world. 

Tropical insects and other species which are sensitive to even more modest variations in temperature than those creatures living in the world’s tundra risk extinction with climate change.  While moderate and cold weather animals are accustomed to large temperature changes, tropical species live under a much more narrow temperature range—thus, these insects face a greater risk of extinction with an increase of merely two to four degrees Celsius according to research published in the Proceedings of the National Academy of Sciences.

The University of Washington researchers responsible for this study examined daily and monthly global temperatures from 1950 to 2000.  They superimposed climate model projections for warming in the first years of the 21st century drawn up by a United Nations Intergovernmental Panel on Climate Change.  The scientists then compared the information with data describing the link between temperature and fitness for 38 temperate and tropical insects as well as cold-blooded animals such as frogs, lizards and turtles.

They concluded that unlike cold weather animals that can more readily adapt to significant climate change by for example, developing thick fur, tropical species do not have the same mechanisms for adaptation.  Rather, they must use other tactics to protect themselves from higher temperatures such as staying out of direct sunlight or burrowing into the soil.  Unfortunately, it is apparent that the warmer weather brought on by climate change may arrive too quickly for their physiologies to timely respond.   

“In the tropics many species appear to be living at or near their thermal optimum, a temperature that lets them thrive,” remarked Joshua Tewksbury, an assistant professor of biology at the Seattle, Washington University.  “But once temperature gets above the thermal optimum, fitness levels most likely decline quickly and there may not be much they can do about it,” he said.

“Many tropical species can only tolerate a narrow range of temperatures because the climate they experience is pretty constant throughout the year,” said Curtis Deutsch, an assistant professor of atmospheric and oceanic sciences at UCLA and a co-author of the study.  “Our calculations show that they will be harmed by rising temperatures more than would species in cold climates,” he added.

“Unfortunately, the tropics also hold the large majority of species on the planet,” said Deutsch.

Climate change—affecting all creatures, great and small.