Ice sheets are melting, glaciers are shrinking and the planet’s oceans are changing in “unprecedented” ways, according to a shocking new report the United Nations released Wednesday, the latest confirmation that climate change is already wreaking havoc around the globe.

The findings, published by the Intergovernmental Panel on Climate Change, or IPCC, the leading U.N. body studying human-caused global warming, issue stark warnings for hundreds of millions of people living in low-lying or coastal areas and come amid a renewed call from scientists who say the planet is quickly running out of time to stave off the worst impacts of climate change.

At a news conference Wednesday in Monaco, IPCC Vice Chair Ko Barrett said the world’s oceans have acted “like a sponge, absorbing carbon dioxide and heat to regulate the temperature.”

“But it can’t keep up,” she said. “These changes show that the world’s ocean and cryosphere have been taking the heat from climate change for decades; the consequences for nature and humanity are sweeping and severe.”

“What is at stake,” she said, “is the health of ecosystems, wildlife and importantly the world we leave for our children.”

The report was written by more than 100 scientists from 30-plus countries, and is the third such paper published by the IPCC over the past year (an August report focused on protecting land, and one last October found time was rapidly running out to avoid catastrophic warming).

“Each year that we delay action, ocean waters warm and become more acidic. This fuels hurricanes, kills coral reefs, and threatens the safety and livelihoods of the 40% of the world’s population who lives within 60 miles of the coast,” Miriam Goldstein, a director of ocean policy at the Center for American Progress, said in a statement this week. “To protect the ocean’s natural ability to store carbon, to feed billions of people across the world, and to save ocean ecosystems, we must substantially reduce greenhouse gas emissions as quickly as possible.”

The report, which focuses on the ocean and the cryosphere, or the frozen parts of the planet, comes a little more than three weeks after Hurricane Dorian slammed into the northern Bahamas as a catastrophic Category 5 storm, obliterating entire communities and flooding 70% of Grand Bahama, an island of some 50,000 people. It also comes amid worldwide calls for dramatic climate action. More than 4 million people around the globe staged mass climate strikes in thousands of cities last Friday, spurred by the 16-year-old Swedish activist Greta Thunberg, and many more are expected to step out again on Sept. 27.