The new report, compiled by a U.N. panel of more than 100 climate change experts and released Wednesday, warns the oceans and ice around the world are experiencing serious consequences from climate change that are already irreversible -- but the impacts can be limited from even worse scenarios if greenhouse gas emissions are drastically reduced.
“Taken together these changes show that the world’s ocean and cryosphere have been taking the heat for climate change for decades," Ko Barrett, deputy assistant administrator at the National Oceanic and Atmospheric Administration and a vice-chair on the report said Wednesday.
"The consequences for nature and for humanity are sweeping and severe.”
The ocean has absorbed over 90% of the heat from global warming in the last 50 years, as well as excess carbon dioxide, which raises the temperature of the water, makes it more acidic and displaces oxygen, which can be devastating for sea life.
The U.N. climate panel warns that Arctic sea ice and permafrost could also release more greenhouse gases as they melt and that ice melt is becoming more severe and possibly irreversible, which would contribute to additional sea-level rise.
The increased sea level rise will increase the threat of severe flooding events for coastal cities, islands, and other areas vulnerable to rising tides. The report found that sea levels could rise one to two feet by 2100 even if greenhouse gas emissions are sharply reduced, but would be even higher if emissions continue to increase.
Members of the UN panel said their reports have emphasized the urgent and immediate need to reduce greenhouse gas emissions to prevent the impacts on the climate, land, and oceans from becoming irreversible.
"We need to take immediate and drastic action to cut emissions right now and especially right from the next year if we want to achieve this carbon neutrality in the mid of the century, and that is the message we’ve found in our three special reports," said Hoesung Lee, chair of the U.N. climate panel and an endowed chair at Korea University Graduate School of Energy and Environment.
The same panel released a report last month that found temperatures are rising more quickly on land and warning that countries will need to address land use and deforestation to meet goals to limit warming from climate change.
The report says the ocean could become a more difficult place for sea life to survive, which could threaten seafood production in the U.S. and around the world. At the same time, another group of experts and world leaders say eating more seafood could be a big part of combating climate change as a way to replace the resource-heavy red meat that's a staple in some western diets.
"There is a lot of opportunity in the ocean to help address the climate change problem. So we need to think about the ocean not just as a victim but the ocean as a powerful source of solutions to climate change," said Jane Lubchenco, former administrator of the National Oceanic and Atmospheric Administration and distinguished professor at Oregon State University who served as an expert for the High Level Panel for A Sustainable Ocean Economy.
That panel of experts and world leaders found the ocean could help reduce up to a fifth of the greenhouse gas cuts needed to limit warming to 1.5 degrees Celsius by 2020, in line with the goals of the Paris Agreement. The panel called for expanding renewable energy sources like offshore wind power, protecting marine ecosystems that can trap carbon dioxide, cutting carbon dioxide emissions from the shipping industry and shifting diets to rely more on seafood as protein.
One of the solutions discussed in that report is that making protein from seafood and other sea-based products, such as seaweed, a bigger part of our diet would cause less emissions than producing food on land, especially resource-intensive areas like beef. The report cites research that sustainably produced food from the sea can have the lowest greenhouse gas footprint per unit of protein than any other source of protein and that reducing the carbon footprint of seafood production and including more seafood in diets would "contribute significantly to climate change mitigation."
"You don't need to fish for other fish to feed them and we don't need to grow soybeans to feed them, so there's very little environmental impact," said Craig Hanson, vice president of food, forests, water and the ocean at the World Resources Institute, which sponsored the report.
The diet portion of the recommendations mirrors discussion in the earlier U.N. report that shifting food systems away from production of livestock, such as beef and lamb, could help reduce greenhouse gas emissions from agriculture.
Hanson said making our food system more efficient could make a big dent in climate change, both by maximizing the food we produce and limiting how much is wasted. Most of the recommendations are in line with a healthier diet, too, including eating more fruits and vegetables and smaller portion sizes.
"If every human did that we'd have a huge impact on climate change and your health," he said.
Hanson said consumers can check resources on sustainable seafood like the Marine Stewardship Council to see the most sustainably fished sources and types of fish.
The combined benefits of those changes could reduce more greenhouse gas emissions than all the coal-fired power plants around the world, according to the report released on Monday.
"Coupled with land-based emissions cuts, it shows that ocean-climate action could provide a lifeline for the economies, food sources, coastal communities and sea life at the frontline of climate disruption," Erna Solberg, co-chair of the panel and prime minister of Norway, said in a statement.