The UN’s Intergovernmental Panel on Climate Change (IPCC) released a comprehensive special report on Wednesday about the effects of the human-driven climate crisis on Earth’s oceans. As is now unfortunately customary, the findings are incredibly dire.
Here are some of the report’s findings and predictions: Earth’s oceans are becoming more acidic and less oxygenated, and marine heatwaves have doubled since 1982, making the seas increasingly inhospitable to life; collapsing marine food webs threaten the food and livelihoods of billions of people; rising sea levels and intensifying superstorms threaten to destroy and displace communities around the world; ocean animals are already on the move, migrating toward the poles at an average rate of 32 miles per decade, seeking relief from warming waters.
Authored by more than 100 researchers and compiled from nearly 7,000 studies, the IPCC report confirms that Earth’s marine habitats and its cryosphere—our planet’s water ice regions—are suffering drastic changes as a result of anthropogenic greenhouse gas emissions fueling climate change.
“The open sea, the Arctic, the Antarctic, and the high mountains may seem far away to many people,” said Hoesung Lee, chair of the IPCC, in a statement. “But we depend on them and are influenced by them directly and indirectly in many ways—for weather and climate, for food and water, for energy, trade, transport, recreation and tourism, for health and wellbeing, for culture and identity.”
Marine scientists, coastal communities, and commercial fisheries have been sounding the alarm about these changes for decades, but the new IPCC report collates their warnings into an interlinked global picture.
One of the most devastating pressures on the ocean is the shrinking of the cryosphere, which is the biome undergoing the most rapid transformation due to climate change. The IPCC report found that ice melt from Greenland, Antarctica, and mountain glaciers are the dominant force behind global sea level rise.
Even if humans manage to reduce greenhouse gases enough to stay within a 1.5°C global temperature increase, ocean levels will still rise by a foot or two by 2100, the report said. But if we don’t meet that target, sea levels could increase by three feet, or more, by the end of the century. This would disrupt coastal habitats and communities around the world, to say nothing of the devastating effects it will have on polar and glacial ecosystems.
Just as these frozen water regions are being reshaped by climate change, so are the ocean’s warmest regions. Marine heatwaves, which can wipe out entire local ecosystems, are twice as frequent as they were 30 years ago, and are expected to become 20 to 50 times more common this century.
These extreme events, along with increasing acidification and oxygen depletion, are already disrupting marine migrations in the sea. Species such as cod, haddock and mackerel, which are important sources of food and income for humans, have expanded their distributions by hundreds of miles to escape the changes at lower latitudes.
In addition to experiencing food and economic losses from these changes, humans across the world will increasingly be battered by extreme storm surges and floods caused by warming, rising waters. The IPCC report projects that surges that would have been considered “once in a century” disasters in the early 1900s will be annual events for many low-lying coastal communities by 2050.
It’s understandable to be overwhelmed or intimidated by the depth of this problem, and there’s no question that Earth’s oceans and cryosphere have already sustained permanent damage as a result of human activity. But the more extreme projections, which reflect a world in which we fail to meet IPCC targets, is still a preventable future, according to the report.
“We will only be able to keep global warming to well below 2°C above pre-industrial levels if we effect unprecedented transitions in all aspects of society, including energy, land and ecosystems, urban and infrastructure as well as industry,” concluded Debra Roberts, co-chair of IPCC Working Group II, in a statement.
“The more decisively and the earlier we act, the more able we will be to address unavoidable changes, manage risks, improve our lives, and achieve sustainability for ecosystems and people around the world—today and in the future,” Roberts said.