Rates of extinction in protected marine animals are set to rise rapidly as they will not be able to tolerate warming ocean temperatures caused by greenhouse gas emissions, according to new research.

Marine protected areas (MPA) have been established as a haven to protect threatened marine life, like polar bears, penguins and coral reefs, from the effects of fishing and other activities like mineral and oil extraction.

A new paper from the University of North Carolina at Chapel Hill found that with continued “business-as-usual” emissions, the protections currently in place won’t matter, because by 2100, warming and reduced oxygen concentration will make marine protected areas uninhabitable by most species currently residing in those areas.

“Many, if not most” of the animals living in protected parts of the world’s oceans could become extinct by the end of the century, the study states. Already many of these marine species exist as small populations with low genetic diversity.

Global warming heat map Image credit: the University of North Carolina

There are currently 8,236 MPAs around the world, covering 4 per cent of the total surface of the oceans, which are on average predicted to rise in temperature by 2.8°C by 2100.

Marine protected areas in the Arctic and Antarctic are projected to warm especially quickly meaning that polar bears and penguins are among the species under greatest threat.

The new study calls for drastic action to stop these areas from being “devastated” by rapid global warming.

Lead scientist Professor John Bruno, from the University of North Carolina in the US, said: “With warming of this magnitude, we expect to lose many, if not most, animal species from Marine Protected Areas by the turn of the century.

“To avoid the worst outcomes, we need to immediately adopt an emission reduction scenario in which emissions peak within the next two decades and then decrease very significantly, replacing fossil fuels with cleaner energy sources like solar and wind.”

The scientists carried out simulations to model sea surface temperatures and oxygen concentrations in MPAs around the world, including those where fishing is banned.

They found that even under the Intergovernmental Panel on Climate Change (IPCC) “business-as-usual” emissions scenario, MPAs were expected to warm by 0.034°C per year.

For each MPA, the scientists calculated a “community thermal safety margin” (CTSM) - the critical point after which most species would not be able to tolerate further change in their living conditions.

In tropical areas, this threshold is expected to be reached by about 2050.

Co-author Rich Aronson, an ocean scientist at the Florida Institute of Technology, said: “There has been a lot of talk about establishing marine reserves to buy time while we figure out how to confront climate change.

“We’re out of time and the fact is we already know what to do. We have to control greenhouse gas emissions.”