Global Warming Could Shrink Mammal Size

Global warming in the past shrunk the size of mammals and according to experts, it might happen again.

Philip Gingerich at University of Michigan and his colleagues recently presented a research at the Society of Vertebrate Paleontology. They said that there is enough evidence to support the idea that mammals could shrink in size due human-led global warming.

Previous research, too, has shown that rising carbon dioxide levels could reduce animal body size in the future.

The first time global warming caused dwarfism was during the Paleocene-Eocene Thermal Maximum (PETM) that occurred about 55 million years ago. The latest research found proof that a similar shrinking occurred about 2 million years after PETM.  

"The fact that it happened twice significantly increases our confidence that we're seeing cause and effect, that one interesting response to global warming in the past was a substantial decrease in body size in mammalian species," said Gingerich, a professor of earth and environmental sciences.

Hyperthermals are periods when global temperatures increase causing animals to adopt several changes for survival. Researchers said that reducing body size might be a common evolutionary response to change in climate.

During the PETM, which lasted for 160,000 years, average global temperatures rose by nine to 14 degrees Fahrenheit. The next event that triggered dwarfism lasted about 80,000 to 100,000 years and is called the ETM2 (Eocene Thermal Maximum 2).

"Interestingly, the extent of mammalian dwarfism may be related to the magnitude of the hyperthermal event," said Abigail D'Ambrosia of the University of New Hampshire and one of the study authors, according to a news release.

For the study, researchers used analyzed fossils of early hoofed animals from Wyoming's Bighorn Basin.

In 2006, Gingerich had proposed that animals shrink during global warming events because plants fail to produce enough nutrients.