Global Sea Ice Hits a New Low
Earth is missing a lot of sea ice this year. Enough to cover the entire United States east of the Mississippi.
That was announced by researchers at NASA and the National Snow and Ice Data Center on Thursday, who said the amount of sea ice on the planet had reached the lowest level ever recorded in March.
The record comes days after the World Meteorological Organization reported that the past 10 years have been the 10 hottest on record, with 2024 the hottest year. The global rise in temperatures is tied to increasing concentrations of greenhouse gases, largely caused by the burning of fossil fuels.
“Warming temperatures drive melting ice across the globe, and because we’re seeing such high temperatures, it’s not surprising that this year we’re seeing the least amount of ice coverage,” said Linette Boisvert, an ice scientist at NASA’s Goddard Space Flight Center.
The center has been compiling data for almost 50 years, primarily through a Department of Defense satellite program. The global sea ice extent includes measurements taken in both the Southern Hemisphere and the Northern Hemisphere, which experience opposite seasons.
Dr. Boisvert compared the freezing and melting of sea ice between winter and summer to the heartbeat of the planet. The pulses between the winter maximum and summer minimum used to be shorter. But with more sea ice melting away, the distance between pulses has grown larger.
“It’s like the heartbeat of the planet is slowing down,” Dr. Boisvert said. “It’s not good.”
Sea ice plays many important roles for the global climate: Its white surface can reflect energy back into space, helping the planet cool. It also acts like a blanket for the ocean, insulating it and preventing ocean heat from reaching the atmosphere. Less sea ice means more heat goes in Earth’s systems, warming the atmosphere and the oceans.
The extent of sea ice isn’t the only measurement scientists are tracking. The thickness of the ice also matters and, since the 1980s, Arctic sea ice has become thinner.
While thicker sea ice tends to survive the summer melt, nowadays most of the sea ice completely melts during the summer, preventing it from thickening year after year. More open ocean means more dark surfaces to absorb more heat from the sun, which in turn melts more ice. The melting becomes its own positive feedback loop.
Changes in remote polar regions affect the rest of the globe, including changes to ocean currents and weather patterns.
“It’s really important to have scientists’ eyes on the data,” Dr. Boisvert said. “It would be really detrimental not to have funding for this type of work.”
Melting sea ice also has negative implications for marine life, tourism in polar regions and global shipping. It’s important for military activities, Indigenous communities in Alaska and the fishing industry, according to Walt Meier, a senior research scientist at the National Snow and Ice Data Center, a research organization at the University of Colorado, Boulder. The trend of decreasing sea ice in the Arctic is an increasingly clear indicator of global warming, he said.
“We’re seeing something that’s pretty unprecedented, at least on scales of human society for thousands of years,” Dr. Meier said.
Under the Trump administration, scientific agencies monitoring weather and climate data have been under threat. In March, NASA fired its chief scientist and eliminated more than a dozen other senior positions. The National Oceanic and Atmospheric Administration, which collects global climate data, fired hundreds of probationary employees in February and officials said officials they had plans to shrink its work force by nearly 20 percent. Projects focused on polar regions lost managers who oversee research when the National Science Foundation laid off about a tenth of its work force.
When asked about the cuts, Dr. Meier noted that groups in Europe and Japan also monitor global sea ice.
“It’s not like there’s not going to be any knowledge of what’s going on in the Arctic, regardless of what happens in the U.S.,” he said
“But I, and I think all of us here at N.S.I.D.C., are focused on the data and our research and doing our best to serve the public by keeping people informed on what’s happening in the polar regions.”
