Most of North America's Lizards Species Now 'At Risk'

Most lizards in North America could suffer severe population decline due to the combined effects of deforestation and climate change, a new study has found.

A new study published in Nature Climate Change found that deforestation, paired with the effects of climate change could harm 84 percent of lizards living in the United States by the end of this century. The scientists from the University of Colorado Boulder and Tel Aviv University in Israel estimate that 1 in 5 species could start losing numbers.

Lizards are cold-blooded, meaning they have limited options to control their body temperature. The study states that some species of lizard rely on climbing trees to bask in the sun's warmth and climb higher in the trees when they need shade.

This means that deforestation and the effects of climate change, with weather patterns becoming more extreme, could be a major problem for the species.

"What's really interesting about lizards is that they just need to be able to move a short distance around the tree trunk to get to a very different climate and habitat environment," Keith Musselman, an assistant professor in the Department of Geography and CU Boulder's Institute of Arctic and Alpine Research, said in a summary of the findings.

"These microhabitats are particularly important when we think about how we modify our natural environment and make conservation decisions."

The scientists found through simulations that global warming alone could be beneficial to lizards living in higher regions or colder areas, as they thrive more in warmer temperatures. But when paired with deforestation, it could seriously start to affect populations.

A lack of trees could start having serious knock-on effects for the species, particularly as weather gets warmer, according to the study.

Through the same simulations, scientists found that by the end of the century, tree loss could decrease the reptile's activity time by 34 percent. Without trees, they will be forced to find other areas of shelter such as under rocks or in caves.

In the U.S., the research team estimated that deforestation would decrease numbers for 18 percent of all lizards. Other studies have already found that lizards are particularly susceptible to changes in the climate, as they are slow to adapt.

"Our work provides new insights into the mechanisms by which deforestation may cause population declines in the face of climate change," Ofir Levy, a zoologist and Musselman's collaborator at Tel Aviv University said in the statement. "The decline in lizards can lead to a cascading effect as they are an important part of almost every ecological system."

Deforestation is occurring at a rapid rate for various reasons including urban development and timber purposes. Pledges have been made globally to reduce the rate at which it is happening, however about 12 percent of global tree cover disappeared between 2001 and 2022, the study reports.

"Here in the Rocky Mountains, elevation provides an escape for animals that can travel longer distances, including us humans. On those summer days when it hits 100 degrees, many of us will go into the mountains. But small animals like lizards can't travel far. They heavily depend on the refuge provided by the local landscape, including tree trunks," Musselman continued. "The study highlighted the importance of understanding which elements in the environment can serve as refuges for other organisms on this planet."

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about lizards? Let us know via science@newsweek.com.