Sharks Could Cope with Climate Change, Study Suggests

Shark fossil teeth recently found in the Arctic Ocean suggest that the predators, despite the rising salinity of Arctic waters, could cope with climate change, according to a new study.

According to the International Union for Conservation of Nature, sharks are already in trouble, with 25 percent of shark species now threatened with extinction. Now with climate change adding to their plight, some worry that the decreasing salinity of their native waters - caused in part by melting ice on land and increased precipitation - could wipe them out entirely.

But new research published in the journal Geology offers some hope for these marine creatures.

The study looked at sand tiger shark teeth found on Banks Island, the westernmost part of the Canadian Arctic archipelago. The teeth date back to the Eocene epoch 38 to 53 million years ago, when the region had a temperate climate and its water had a lower salinity.

That time is like a "deep-time analogue for what's going to happen if we don't curb carbon dioxide emissions today, and potentially what a runaway greenhouse effect looks like," lead researcher Sora Kim of the University of Chicago said in a statement.

Kim isolated and measured the mass ratio of oxygen isotopes found in the shark teeth - a measure that tends to reflect ocean temperature and salinity.

"The numbers I got back were really weird," Kim said. "They looked like fresh water." Sand tiger sharks, part of a group called lamniform sharks, prefer waters with high salinity.

These findings suggest that sharks may be able to cope with rises in temperature and the subsequent decrease of water salinity. It has long been known that sharks are hardy creatures, and this study backs that notion.