not enough Paris Agreement target won’t protect polar ice sheets, scientists warn Calls for a more ambitious climate goal are rising as Earth hits several tipping points. Bob Berwyn, Inside Climate News – May 21, 2025 11:35 am | 21 A slurry mix of sand and seawater is pumped via barge onto the main public beach during a sand replenishment project along eroding shoreline on November 21, 2024, in San Clemente, California. Credit: Mario Tama / Getty Images A slurry mix of sand and seawater is pumped via barge onto the main public beach during a sand replenishment project along eroding shoreline on November 21, 2024, in San Clemente, California. Credit: Mario Tama / Getty Images Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only   Learn more This article originally appeared on Inside Climate News, a nonprofit, nonpartisan news organization that covers climate, energy, and the environment. Sign up for their newsletter here. Sea levels in some parts of the world could be rising by as much as 8 to 12 inches per decade within the lifetime of today’s youngest generations, outpacing the ability of many coastal communities to adapt, scientists warned in a new study published this week. The research by an international team of sea level and polar ice experts suggests that limiting warming to 2.7° Fahrenheit (1.5° Celsius) above the pre-industrial temperature—the Paris Climate Agreement’s target—isn’t low enough to prevent a worst-case meltdown of Earth’s polar ice sheets. A better target for maintaining a safe climate, at least for the long term, might be closer to 1.8° Fahrenheit, said Durham University geographer and glacier expert Chris Stokes, a co-author of the new paper. “There have been a couple of quite high-profile papers recently, including a synthesis in Nature looking at safe planetary boundaries,” he said. “They made the argument that 1° Celsius is a better goal. And a couple of other papers have come out suggesting that we need a stricter temperature limit or a long-term goal. And I think the evidence is building towards that.” It’s not a new argument, he said, noting that climate research predating the first Intergovernmental Panel on Climate Change report in 1990 already highlighted the high risks of more than 1° C of warming. “Those studies were saying, ‘We’re warming. We really don’t want to go past 1°. We really don’t want to exceed 350 parts per million of carbon dioxide,’” he said. “Because we know what could happen looking at past warm periods and at simple calculations of ice sheet mass balance. And, you know, 30 years later, 40 years later, here we are seeing the problem.” Scientific calls for a more ambitious long-term climate goal are rising just as Earth’s average global temperature has breached the Paris Agreement target of 1.5° C of warming over the pre-industrial level nearly every consecutive month for the past two years. Atmospheric carbon dioxide has reached a concentration of 430 ppm, a 50 percent increase over pre-industrial levels. But missing those goals doesn’t diminish the importance of potentially revising the target, for which the Paris Agreement includes a review mechanism, Stokes said. Even if the global temperature overshoots the 1.5° mark, it’s important to know for the long term how much it would have to be lowered to return to a safe climate range. The new study focused on how melting polar ice masses drives sea level rise by combining evidence from past warm periods that were similar to the present, measurements of how much ice is being lost under the present level of warming, and projections of how much ice would be lost at different warming levels over the next few centuries. Sea level rise of several inches per decade would likely overwhelm adaptation efforts by many coastal communities in the US, said co-author Andrea Dutton, a geoscientist and sea level expert at the University of Wisconsin-Madison. “Coastal communities that are adapting to and preparing for future sea level rise are largely adapting to the amount of sea level rise that has already occurred,” she said. In a best-case scenario, she added, they are preparing for sea level rise at the current rate of a few millimeters per year, while the research suggests that rate will double within decades. The last time atmospheric carbon dioxide was at a concentration similar to now was in the mid-Pliocene warm period, just over 3 million years ago, when average global sea level rose 35 to 70 feet higher than today over the course of thousands of years. But the current rate of warming is far faster than any other time identified in the geological record. How the ice sheets will respond to warming at that speed is not clear, but nearly every new study in the past few decades has shown changes in the Arctic happening faster than expected. The United States’ ability to prepare for sea level rise is also profoundly threatened by the cuts to federal science agencies and staffing, Dutton said. The current cuts to science research, the retraction of funds already promised to communities through the Inflation Reduction Act of 2022, the abandonment of the congressionally mandated National Climate Assessment, and changes to federal rules on air pollution “collectively threaten our ability to project future sea level rise, to prepare our communities, and to mitigate climate change and stem the rate at which sea-level is rising,” she said via email. Many researchers are working closely with coastal communities, but as federal grants continue to get cut, these collaborations will founder, she added. “The ice sheets won’t care what different political parties ‘believe’ about climate change,” she said. “Like it or not, they are simply at the mercy of rising temperatures.” The mass of ice lost from the polar ice sheets has quadrupled since the 1990s, and they are currently losing around 370 billion metric tons of ice per year, said co-author Jonathan Bamber, a physicist at the University of Bristol who focuses on studying how Earth’s frozen regions interact with the rest of the climate system. “We switched on some new technology 30 years ago, and we discovered that the ice sheets are responding with a large amplitude and rather rapidly,” he said. The extent of the changes to the ice sheet are much greater than models had ever suggested they would be, he noted. “That was a bit of a shock for the whole community.” Most of the climate models of the past three decades projected only about half as much melting as has actually been observed during that time, he said. That suggests the “safe operating zone for humanity is about 350 ppm” of atmospheric carbon dioxide, corresponding to about 1° C of warming. “I think we’ve known for a long time that we’re interfering with the climate system in a very dangerous way,” he said. “And one of the points of our paper is to demonstrate that one part of the climate system, the ice sheets, are showing some very disturbing signals right now.” Some of the most vulnerable places are far from any melting ice sheets, including Belize City, home to about 65,000 people, where just 3 feet of sea level rise would swamp 500 square miles of land. In some low-lying tropical regions around the equator, sea level is rising three times as fast as the global average. That’s because the water is expanding as it warms, and as the ice sheets melt, their gravitational pull is reduced, allowing more water to flow away from the poles toward the equator. “At low latitudes, it goes up more than the average,” Bamber said. “It’s bad news for places like Bangladesh, India, Vietnam, and the Nile Delta.” Global policymakers need to be more aware of the effects of a 1.5° C temperature increase, Ambassador Carlos Fuller, long-time climate negotiator for Belize, said of the new study. Belize already moved its capital inland, but its largest city will be inundated at just 1 meter of sea-level rise, he said. “Findings such as these only sharpen the need to remain within the 1.5° Paris Agreement limit, or as close as possible, so we can return to lower temperatures and protect our coastal cities,” Fuller said. While the new study is focused on ice sheets, Durham University’s Stokes notes that recent research shows other parts of the Earth system are already at, or very near, tipping points that are irreversible on a timescale relevant to human civilizations. That includes changes to freshwater systems and ocean acidification. “I think somebody used the analogy that it’s like you’re wandering around in a dark room,” he said. “You know there’s a monster there, but you don’t know when you’re going to encounter it. It’s a little bit like that with these tipping points. We don’t know exactly where they are. We may have even crossed them, and we do know that we will hit them if we keep warming.” Bob Berwyn, Inside Climate News 21 Comments