Do Global Warming and Climate Change Affect Animal Size?

Do global warming and general climate change have an impact on plant and animal size?

Plants and animals are shrinking: New research suggests that climate affects the overall size of life on our planet, and we’re downsizing.

A report in the journal Nature Climate Change and shared on Huffington Post Green states that 38 of 85 animal and plant species, reviewed from other studies, have shown a documented reduction in size.

Polar bears are getting smaller, as are house sparrows, along with many other animal species including shrimp, crayfish, herring, Atlantic salmon, iguanas, frogs, lynx, and California squirrels. Between 1950 and 1990, the house sparrow’s weight dropped by one-seventh, and the graceful warbler’s weight dropped 28 percent.

Corn, cotton and strawberries are among the plant species that are shrinking. The report’s authors suspect it’s due to global warming, comparing the phenomenon to “wool sweaters that shrink when washed in hot water.”

Jennifer Sheridan, a biology researcher at the University of Alabama, also weighed in on the results. "There is a trend in a number of organisms across the board from plants to big vertebrates getting smaller," she said. "The theory is as things get warmer, they don't need to grow as large."

It makes sense; the warmer the weather, the faster the metabolism, thus more calories are burned and overall weight / size is lost. On the flip-side, as it gets colder, animals get bigger since they aren't burning as many calories due to a slower metabolism.

Studies by Tel Aviv University zoologist Yoram Yom-Tov (which used Sheridan's research) concluded that while many species are shrinking, global warming cannot be blamed exclusively.

"Changes in body size are a normal phenomenon," Yom-Tov wrote in an email. "When conditions are favorable, [animals] increase in size or reproduce at higher rates, and when conditions are deteriorating, they do the opposite. I think that most species will adapt to climate change and survive. No need for alarm."

Basically disagreeing with the Journal’s report, climate change expert and Stanford biologist Terry Root called the new study's conclusions "kind of far-fetched."

I found the new research report fascinating and thought provoking so I did a little digging of my own. According to the Florida Museum of Natural History, 55 million years ago the predecessor of the modern horse was a dog-sized forest dwelling mammal called Eohippus, or the "dawn horse.”

This small animal bore no resemblance to today’s horse. But with radical climate changes leading to suitable and plentiful vegetation, along with natural selection adjusting to these changes, the little “dawn horse” grew larger and taller, able to run faster to avoid predators and to take more advantage of their environment. They slowly evolved into our modern horse over the ages.

It makes me wonder why we’re headed back in the other direction.

Do you agree that “global warming” actually affects our animal and plant life? Share your opinion in a comment.