The world’s oceans are likely to lose around a sixth of their fish and other marine life by the end of the century if climate change continues on its current course, a new study has found.
For every degree Celsius (1.8 degrees Fahrenheit) that the world’s oceans heat up, the total mass of marine animals is expected to drop by 5%, according to an extensive computer study by an international team of marine biologists. And this does not include the effects of fishing.
If global greenhouse gas emissions remain at the current rate, this means a 17% biomass loss – the total weight of all marine animal life – by the year 2100, according to Tuesday’s study in the Proceedings of the National Academy of Sciences. But if the world reduces carbon pollution, the losses can be limited to just around 5%, the study found.
“We’ll see a big decline in ocean biomass,” if the world doesn’t slow climate change, study co-author says Guillaume Cheunga marine ecologist at the University of British Columbia. “There are already changes that have been observed.”
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While warmer water is the most important factor, climate change is also producing oceans that are more acidic and have less oxygen, which also harms marine life, Cheung said.
According to scientists, much of the world depends on the oceans for food or livelihoods.
“The potential ramifications of these predicted losses are enormous, not just for ocean biodiversity, but because people around the world depend on ocean resources,” said Julia Baum, a biology professor at the University of Victoria, who is not didn’t participate in the study but says it makes sense. “Climate change has the potential to cause serious new conflicts over ocean resource use and global food security, especially as the human population continues to grow this century.”
The largest animals in the oceans will be the hardest hit, said study co-author Derek Tittensora marine ecologist at the United Nations World Conservation Monitoring Center in England.
“The good news here is that the main building blocks of marine life, plankton and bacteria, may decline less sharply, the bad news is that the marine animals we directly use and care about most deeply are set to suffer the more because climate change is moving up the food chain,” the co-author said. Boris Worma marine biologist at Dalhousie University in Canada.
Already hot tropical areas will also see the greatest losses, Cheung said.
In a world shrouded in darkness, these fish may have a unique way of seeing colors.”
Scientists already thought that climate change was likely to reduce future ocean life, but past computer simulations have only looked at part of the picture or used just one model. This study uses six different state-of-the-art computer models that give the best overview yet, he said.
It is difficult to separate the past effects of climate change from those of fishing, but previous studies have shown places where observed fish loss can be attributed to human-induced climate change, Cheung added.
Tittensor cited lobsters off Maine and right whales in the North Atlantic as examples of creatures already affected by global warming hitting the ocean.
University of Georgia Marine Biologist Samantha Joyewho was not involved in the research, called the study meticulous and said it was also “an urgent call to action”.
“Healthy oceans are necessary for planetary stability,” Joye said in an email. “Aggressive global action to slow climate change is a moral imperative.”
Borenstein writes for the Associated Press.