Reptiles that 'tolerate heat and should be well buffered against warming are the victims' as world enters 'era of climate change extinctions'
Celia Cole, The Guardian
The research found that more than a 10th of Mexico's Sceloporus lizard populations have been driven to extinction in the last 35 years, with the figure projected to increase to almost 40% by 2080. The scientists projected their findings globally using data from other lizard populations around the world.
The findings come in the wake of immense criticism over the failure of world leaders to live up to a commitment to reduce biodiversity loss by 2010. Professor Barry Sinervo at the University of California, Santa Cruz, who led the study, said he believes "we have now entered the era of climate change extinctions".
Global maps of observed local extinctions in 2009, and projections for 2050 and 2080 based on geographic distributions of lizard families of the world. Illustration: Barry Sinervo
Although we may not be accustomed to considering lizards as important players within our ecosystems in the UK, he warns that the reptiles occupy diverse ecological roles in ecosystems across the globe and their reduced numbers will have important implications for ecosystems and maintaining species diversity. "Their loss could cause a collapse at higher levels of the food webs," he said.
"Many people appreciate that climate warming may lead to extinction in the future," said Prof Raymond Huey an evolutionary physiologist at the University of Washington, who was not directly involved in the study. "But this paper shows that climate-induced extinction has already arrived and that more is coming. What is especially concerning is that lizards – a group of animals that tolerate heat and should be well buffered against warming – are the victims."
Scientists made the initial discovery by distributing an electronic device across 200 sites in Mexico where the lizards were both thriving and had already gone extinct. They found that rapid warming was causing the animals to spend more time in cooler retreats, preventing them from finding food and reproducing at a level able to maintain a stable population size. The reptiles do no produce their own heat internally and so are dependent on the sun.
When the researchers plotted the thermal biological data from the Sceloporus lizards, and more than 1,200 other populations found worldwide, against projected temperature rises they discovered that global warming will drive 39% of all global lizard populations and one fifth of all lizard species to extinction by 2080.
A drastic cut in CO2 production which limited temperature rise might enable losses to be limited to 6% of species, the study predicts. However, given the time lag required for current levels of CO2 to decline in the atmosphere and the projected rise in temperatures that we have already observed, Sinervo believes it is unlikely that more extinctions could be avoided.
Huey said the paper was a call to arms for scientists and policymakers. "This is a mission critical paper that sends urgent messages to two groups. First, it should prompt government officials to draft regulatory changes that may slow the growth of greenhouse gasses. Second, it sends a strong message to biologists - we need to get busy and start studying extinctions [their extent and causes] rather than just predicting future extinctions."