Humans are undoubtedly the biggest contributors to global warming, but now we have another species to share in the blame.
Beavers, long reviled by land owners for damming up rivers and flooding properties, have a far more reaching impact on the environment than we thought.
Scientists say the ponds that collect behind their dams contribute to global warming. The ponds are a crucial part of the beaver's home, but generate vast quantities of methane, which does far more short-term damage to the environment than carbon dioxide. Methane is present in much smaller quantities than carbon dioxide, but is 84 times more potent over a 20 year timespan.
Methane is produced when carbon builds up in the oxygen-poor bottoms of beaver ponds. Since the gas cannot be dissolved in the shallow water, it releases into the atmosphere.
Colin J. Whitfield of the University of Saskatchewan led the study, where he estimated that growing beaver numbers mean their ponds produce methane emissions that are 200 times higher than in 1900. Whitfield predicts that at the end of the 20th Century, beaver ponds released 800 million kilograms of methane to the atmosphere annually. That represents 15 percent of the input from all wild cud-chewing animals such as deer or antelopes.
Between the 16th and 19th Centuries, beaver fur trapping was a booming business that nearly led to the animal's extinction. Trapping was eventually limited and beavers were reintroduced, allowing their numbers to recover over the past century. The beaver population now stands at 10 million worldwide, and they have dammed more than 2,600 square miles of water.
Whitfield sees the beaver problem only continuing to grow as the rodents continues to expand in range and as surface water temperatures increase worldwide.
Of course, the emissions released by beavers are minuscule compared to greenhouse gases produced by humans each year. According to the EPA, 60 percent of methane emissions are still the result of human activity. But the study shows rodents like the beaver play a larger role than previously thought, which could eventually lead to adjustments in climate change models.
While humans may not bear all the blame for global warming, combating it will still be 100 percent our responsibility. After all, it's not like the beavers are going to do anything about it.