Among the species that the authors say are at risk are some of the most commercially important species on Earth. – Including grocery staples like Atlantic cod, Alaskan pollock and sockeye, and sportfishing favorites like swordfish, barracuda and brown trout.
In fact, 60% of the fish species examined may have difficulty reproducing in its current habitat ranges per year 2100 if the climate crisis continues without control, according to the researchers.
However, if governments again commit to keeping global warming at 1.5 degrees Celsius, the scientists found that the number of threatened species could be much less, just 10%.
“More than half of potentially at-risk species is quite surprising, so we really emphasize that it is important to take action and follow through on political commitments to reduce climate change and protect marine habitats,” said Dr. Flemming Dahlke, biologist. Marine from Germany. Alfred Wegener Institute and one of the study’s authors..
The worst-case scenario of the impact of global warming on fish species is even more evidence showing that without radical efforts to reduce heat-trapping gas emissions, human activity threatens to permanently disrupt ecosystems that feed thousands of millions of people.
The study was conducted by a team of researchers based in Germany, who analyzed temperature tolerance data from nearly 700 species of marine and freshwater fish from climate zones around the world.
Effects of heat on key stages of life
Previous studies on the sensitivity of fish to changes in water temperature have mainly focused on adult fish.
But to really understand how warmer waters will affect species, the researchers argued that it’s essential to look at the most vulnerable stages in a fish’s life cycle, those that are critical to the species’ reproduction and survival.
In almost all cases, the embryos and reproducers of fish, female and male fish that are preparing to produce eggs and sperm, are much more vulnerable to abnormally warm water temperatures than adults and larvae, the researchers found.
“There is a difference in the tolerable temperature range of almost 20 degrees on average between embryos and adults,” said Dahlke. “This, of course, makes a big difference when you want to look at the sensitivity of species to global warming.”
Global warming overcomes species adaptation
The consequences for humans could be enormous.
To survive, many species would be forced to evolve to cope with warmer temperatures or move in search of cooler waters, the authors said. But given the speed with which human activity is heating up the planet, many species may not be able to adapt quickly enough to survive.
“If climate change continues unchecked, we will likely see major changes in the species composition of our ecosystems,” said Dahlke. “When species can no longer reproduce in their traditional habitats, they have to go to deeper waters or further north if possible, or go extinct locally if they cannot.”
As the planet warms, several other recent studies have shown how the oceans in particular have been the hardest hit by warming.
There is also evidence that heat is already reshaping aquatic ecosystems.
“The effects of these heat waves predict what might happen at the end of this century.”
This latest study strengthens the evidence that sounds an alarm for government leaders to take meaningful steps to protect the fish species on which people depend.
CNN’s Ivana Kottasova contributed to this story.
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