Warming oceans fish, alarm bells sounding over how climate change.
While there are a lot of alarm bells sounding over how climate change will affect marine ecosystems and the world’s seafood supply in the future, there’s been much less attention paid to the effects it’s already had on them. In fact, the National Oceanic and Atmospheric Administration (NOAA) estimates that more than 90 percent of the earth’s warming over the past 50 years has occurred in the ocean. Now, a new, first-of-its-kind study reveals that ocean warming has significantly affected fisheries worldwide, and it’s done more harm than good.
“Everyone wants to know what the future of our marine resources are — the problem is that getting even basic information is hard,” says Daniele Bianchi, an assistant professor in the Department of Atmospheric and Ocean Sciences at the University of California-Los Angeles. It’s a great starting point, he says, “that they can prove there is this influence, and to do that they had to do a lot of work, not just in this paper, but really collecting all the data.”
Published Thursday in Science, the study used temperature records and maximum sustainable yield data — a metric showing the most that a resource can be exploited without depleting it — from 1930 to 2010 to determine warming impacts on 235 fish and invertebrate populations around the world. (That sample included 124 species in 38 eco-regions, or about a third of the reported global catch.)
“Most people have been looking at forecasting what the anticipated impacts of climate change are going to be on the future of fisheries, but no one has actually looked at what the impact of climate change has already been,” says Chris Free, the study’s lead author and a researcher at the University of California-Santa Barbara. “It helps us figure out some of the factors that make populations more vulnerable to anticipated climate change.” It also highlights just how significantly future warming could affect the studied populations, since the already-observed changes resulted from about a half-degree Celsius in ocean warming. Projections for the future expect more than three times that increase.
Free and his peers from Rutgers University, the University of Washington, and NOAA found that overall, global sustainable fish and shellfish yields decreased by about 4 percent, with some species, like the Atlantic cod in the Irish Sea, faring worse than others. While 4 percent might not seem huge, it’s still a marked drop, and beyond that, the regional differences are especially striking. Alarmingly, yield losses reached almost 35 percent in some eco-regions.