All posts tagged: ice sheets

A counterintuitive effect of global warming

A counterintuitive effect of global warming

This is an edition of Time-Travel Thursdays, a journey through The Atlantic’s archives to contextualize the present and surface delightful treasures. Sign up here. In a 1998 Atlantic cover story, William H. Calvin offered perhaps the best oceanography lesson to appear in a major national magazine. It was also a call for concern: He drew on the research of the legendary Columbia University climate scientist Wallace Broecker to explain the relationship between ocean currents and the climate, and warn about a rather counterintuitive tipping point that our age of global warming could cause. By warming the planet, humanity might kick off a disastrous oceanographic flip-flop. A part of the great underwater conveyor belt called the Atlantic Meridional Overturning Circulation, better known as AMOC, could shut down, he wrote. Enormous inputs of freshwater from melting northern ice or warming-induced rainfall in the high latitudes could dilute the salty Atlantic Ocean and change the temperature balance, throwing off the pace of the North Atlantic Current, which makes up a section of AMOC’s global journey. Instead of warming, …

Earth’s Hot Oceans Are a Cosmic Tragedy

Earth’s Hot Oceans Are a Cosmic Tragedy

The ocean off the coast of southern Florida is having a long, hot summer. For weeks, surface temperatures hovered around 90 degrees Fahrenheit, before dropping to the 80s last week. The world’s third-largest barrier reef is dying, and scientists are fishing out coral samples and bringing them to the cool safety of laboratory tanks. One spot along the coastline hit triple-digit temperatures last month, conditions you would expect inside a hot tub. Some coastal Floridians skipped their usual dips in the ocean because it didn’t seem appealing anymore. Marine heat waves—periods of persistent and anomalously high temperatures of surface seawater—have materialized in other parts of the world too. The surface temperatures of about 44 percent of Earth’s oceans are currently experiencing extreme heat, according to the National Oceanic and Atmospheric Administration. Some of that warming is to be expected, because 2023 is an El Niño year. But “all of these marine heat waves are made warmer because of climate change,” Dillon Amaya, a research scientist at NOAA’s Physical Sciences Laboratory, told me. June was already …