Increasing temperatures, ocean acidification, and deoxygenation are the outcomes from climate change that will cause the most damage the world’s marine economy, according to National Climate Assessment report released by the U.S. Global Change Research Program on Friday, 23 November.
The federal program that released the report was mandated by Congress to coordinate federal research and investments in understanding the forces shaping the global environment and their impacts on society. Compiled by top scientists at 13 U.S. agencies, it paints a grim picture of the future of both U.S. and global fisheries as the effects of climate change continue to advance.
The report stated with “very high confidence” that the world stands to suffer “the loss of iconic and highly valued” habitats, and said intensifying ecosystem disruption as a result of ocean warming, acidification, deoxygenation, and other aspects of climate change will result in major changes in species composition and food web structure. In fact, these changes are already underway and have caused significant shifts in how the marine environment is functioning, especially in the warmest and coldest environments, and the report stated – also with very high confidence – these transformative impacts on ocean ecosystems cannot be avoided In the absence of significant reductions in carbon emissions.
“Warming, acidification, and reduced oxygen conditions will interact with other non-climate-related stressors such as pollution or overfishing,” the report said. “Conservation measures such as efforts to protect older individuals within species, maintain healthy fish stocks, and establish marine protected areas can increase resilience to climate impacts. However, these approaches are inherently limited, as they do not address the root cause of warming, acidification, or deoxygenation. There is growing evidence that many ecosystem changes can be avoided only with substantial reductions in the global average atmospheric CO2 concentration.”
When it comes to fisheries, the impacts of climate change are hard to predict with precision, as the effects of each aspect of climate change are likely to compound the others, causing cascading effects across ecosystems. The report notes that differences in how species respond to changing physical conditions could lead to drastic shifts in both the abundance of certain species, and the locations where they may be found in the future, as they abandon areas where conditions are no longer favorable to them, or as they seek to colonize new locations that may be more amenable to their existence. And this is likely to happen around the world – the report found that 86 percent of global marine ecosystems will experience combinations of temperature and acidification that have never before been experienced by modern species.
“Changes in productivity, recruitment, survivorship, and, in some cases, active movements of target species to track their preferred temperature conditions are leading to shifts in the distribution of many commercially and recreationally valuable fish and invertebrates, with most moving poleward or into deeper water with warming oceans,” the report said.
More alarming, scientists are unable to predict whether marine species can survive these massive disruptions in the long-term.
“Little is known about species’ adaptive capacity and whether the rate of adaptation is fast enough to keep up with the unprecedented rate of change to the environment,” the report said.
The report projected that increases in ocean temperature will lead to declines in maximum catch potential in all U.S. regions except Alaska. Catch potential in Hawaii and the Pacific Islands, the Caribbean, and the Gulf of Mexico will decline between 10 and 47 percent compared to their levels from the years spanning 1950 to 1969. The U.S. East Coast is expected to experience total catch potential declines between 20 and 30 percent, including declines of species that support some of its most valuable and iconic fisheries, including Atlantic cod, scallops, and American lobsters. And on the U.S. West Coast, potential catch will decline by up to 10 percent. The report predicts a 22 percent reduction in salmon habitat in Washington state by the end of the century – a loss valued at USD 3 billion (EUR 2.6 billion).
In contrast, total fish catch potential in the Gulf of Alaska is projected to increase by approximately 10 percent, while Bering Sea catch potential may increase by 46 percent, according to the report. However, the uptick will be the result of new species moving into the newly-warmer waters in the area, with catches of Bering Sea pollock, one of the largest fisheries in the United States, and Pacific cod expected will to decline. Moreover, ocean acidification will have a negative impact on commercially important species such as Tanner crab, red king crab, and pink salmon.
The report notes that unusual climate-related events will have tangential and disrupting effects on the fishing industry. For example, a marine heatwave in the Gulf of Maine in 2012 caused lobster catches to peak one month earlier than usual. And, the warm "Blob" that occurred in the Pacific Ocean from 2014-2015 facilitated the formation of a harmful algal bloom that forced the closure of the Dungeness crab fishery on the West Coast, and disrupted coho and Chinook salmon runs. The report also blamed climate change for less cod abundance and reductions in cod quotas in the Gulf of Maine and in the Gulf of Alaska.
The impacts of climate change are being felt particularly acutely in the world’s oceans, the report said, as more than 90 percent of the extra heat linked to carbon emissions is contained in the ocean. Globally, ocean surface temperatures have increased by nearly 1.3 degrees Farenheit over the past century and and predicted to rise further and faster in coming decades. And as the ocean warms, seawater expands and causes sea levels to rise, and it loses its ability to hold gases including oxygen.
In a response to media questions over the issuance of the report, U.S. President Donald Trump said he distrusted the findings of the 1,600-page report.
"I don't believe it," he said when asked about the conclusions on the report, according to USA Today.
Trump said it did not make sense for the United States to take drastic steps to combat climate change when other countries, such as China and Japan, are not doing so.
Photo courtesy of NASA