From the mighty polar bear to the tiny house sparrow, many of Earth’s species appear to be shrinking in size, a new study reports and its authors think that’s probably due to global warming. But other experts say that conclusion goes too far, blaming global warming for what may be natural changes.
The new research was published online Sunday in the journal Nature Climate Change. It’s based on a review of other studies and found that 38 of 85 animal and plant species showed a documented reduction in size over decades, including a type of Scottish sheep that is 5 % smaller than in 1985. Those studies looked at species over different time periods and in varying numbers.
The shrinking victims, according to the study, include cotton, corn, strawberries, bay scallops, shrimp, crayfish, carp, Atlantic salmon, herring, frogs, toads, iguanas, hooded robins, red-billed gulls, California squirrels, lynx and wood rats.Two years ago, Scottish researchers made news with the shrinking sheep study. Several studies have shown that polar bears, which rely on sea ice during the summer, also are not as big. And this latest study said the house sparrow’s weight has dropped by one-seventh from 1950 to 1990. A bird called the graceful warbler showed a 26% weight drop during the same time period.“There is a trend from plants to big vertebrates getting smaller,” said study co-author Jennifer Sheridan, a biology researcher at the University of Alabama. “The theory is as things get warmer they don’t need to grow as large.”Most of these animals are cold-blooded, so the warmer the weather the faster their metabolism is and the more calories they burn, Sheridan said.