The “IPCC Special Report on Ocean and Cryosphere in a Changing Climate” is a collaboration among 130 scientists around the world who have assembled data from over 7,000 papers in an assessment of the latest science on how climate change impacts the cryopshere and ocean. The cryosphere are the portions of Earth’s surface where water is frozen, including sea ice, snow cover and glaciers.
Last month, the international scientific body released a related report about the effects of climate change on lands, finding increased risks of drought and wildfires already underway. This new report released on 25 September 2019, paints an even bleaker picture, showing that the oceans have been expanding, acidifying, and losing oxygen at an accelerated rate.
This latest special report from the Intergovernmental Panel on Climate Change is of great importance to some of the world’s most vulnerable countries – like small island states and the least developed countries.
“For us in the Pacific, as with all small islands, the report is highly relevant as it covers issues from sea level rise to impacts on coral reef fisheries, and extreme events such as storm surges,” said Mr Kosi Latu, Director General of the Secretariat of the Pacific Regional Environment Programme (SPREP).
In July this year the IMPACT Project coordinated by Climate Analytics coordinated a workshop on the Special Report on Oceans and Cryosphere in partnership with SPREP for 14 Pacific focal points of the IPCC to support countries in contributing to the IPCC government review process, raising awareness of the report and highlighting its relevance to the Pacific islands.
“Many least developed countries will also face severe impacts to their coastlines, as sea levels rise, while melting glaciers spell disaster for millions of inhabitants of mountainous countries. I encourage all of us to take time to read the report.”
Much of the carbon pollution that has been pumped into the air has gone directly into the world’s seas. They have absorbed 90 percent of the excess heat from the atmosphere, warming without pause for the past 50 years. Because oceans are large and complex, covering two-thirds of Earth’s surface, that warming has consequences for the entire planet.
One major takeaway from the report is that the seas are rising twice as fast as the average in the twentieth century. Sea level rise will combine with increases in tropical cyclone winds and rainfall, and increases in extreme waves to exacerbate coastal inundation risks and coastal hazards in Pacific islands.
The ocean is also heating up twice as fast, absorbing more carbon and acidifying. This acceleration of warming and acidification means a cascade of impacts on weather and marine life, such as coral reefs, some of which are still not fully understood. Adverse impacts on ecosystems will have severe implications for island and coastal communities who rely on the services they provide.
"The IPCC report on oceans and cryosphere reinforces the earlier findings of the earlier IPCC 1.5 degrees report. Ocean warming is accelerating, it is becoming more acidic, and so will sea level rise. The changes are also evident in ocean acidification,” said Mr Latu.
“Ocean biomass will be reduced by 10-25 percent by the turn of the century. These developments are of a particular concern to us in the Pacific who depend so much on the ocean. We are now committed to a warmer ocean, even if we scale back our emissions. There is no other solution other than reducing global greenhouse gas emissions.
More work is needed to determine how much and how fast the seas will rise toward the end of the century—and how fast the world’s major ice sheets will melt over hundreds of years, which eventually could raise the ocean’s level by metres.
These metrics depend on how quickly the global community acts on climate change. If carbon emissions are not reduced to near zero by mid-century, the seas are expected to rise by 60 centimetres or more by 2100.
“This new prediction is much more dire than previously stated by the IPCC, because scientists have recently learned that an ice sheet in West Antarctica—one of the world’s biggest—is teetering on the edge of collapse,” said Mr Latu.
As the IPCC Special Report on the Ocean and Cryosphere warns – “These changes may be the onset of an irreversible ice sheet instability.”
Photo of Taveuni, Fiji courtesy of S.Chape