By 2050, extreme sea-level events that used to occur once in a century, including intense storms and drastic reductions in marine life, will happen every year on many coasts. Indeed, the worst-case scenario could mean sea levels will rise by more than four metres. And many serious impacts are already inevitable, according to the stark landmark report from the Intergovernmental Panel on Climate Change (IPCC) released today.
More than 100 scientists from more than 30 countries contributed to the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC), approved by the 193 member nations of the IPCC. The researchers assessed the latest scientific knowledge to determine how climate change is affecting the oceans and cryosphere — water in the solid-state such as glaciers and ice sheets — including coastal, polar, and mountain ecosystems — as well as the projected risks. And, of course, the potential impact on human communities that depend on them.
From threats to water supplies of people living in high-mountain regions to the impact of sea-level rise on coastal communities. But not only that. The report also discusses “how nature and society can respond to the risks this poses and achieve climate-resilient development,” says Prof Hans-Otto Pörtner, Co-Chair of one of IPCC working groups involved in the analysis.
Oceans cover nearly 70 per cent of the Earth’s surface and play an important role in the Earth’s climate and global warming. And as the report states, “all people on Earth depend directly or indirectly on the ocean”. However, global warming is driving unprecedented changes in the ocean and cryosphere.
Global warming has already led to widespread shrinkage of glaciers, reduced snow cover, and permafrost melting – and the latter is releasing large amounts of stored carbon and further contributing to warming. Last July was the hottest month on record and the ocean is warming at all depths with the frequency of marine heatwaves increasing – and having dire effects on marine life.
Since the 1970s, oceans have taken up more than 90 per cent of this additional heat. Ocean warming has likely more than doubled since the early 90s. Increased absorption of carbon by oceans has led to a dramatic increase in surface acidification and loss of oxygen and as a result, not only are there less fish, but the remaining fish are getting smaller. And all of these trends are set to continue to the end of the century, the report states.
The authors also highlight potential vulnerabilities, as well as their adaptation capacities. Small island nations close to the equator are particularly vulnerable. In 30 years, catastrophic tropical storms like the one that recently ravaged the Bahamas could become the norm. And rising sea levels could eventually swallow up coastal communities. Although the exact speed of future sea-level rise remains difficult for scientists to predict since it will largely depend on the fate of the West Antarctic Ice Sheet – its collapse could drive meters of sea-level rise.
What is clear is that unprecedented and dangerous warming events are already having negative impacts on food security, water resources, water quality, and livelihoods, in addition to adverse effects on the health and wellbeing of local communities, particularly those reliant on the fishing industry.
And despite pledges by nations to reduce the use of fossil fuels, the new analysis paints an even drearier picture than the 2014 report. Billions of people are at risk unless urgent actions are taken to drastically cut greenhouse gas emissions. “We can save the cryosphere,” says Dr Ted Schuur, an Associate Professor of Ecosystem Ecology at the University of Florida and one of the authors. Adding that “the rapidity of change sometimes leads people to think it’s too late, and it’s not”.