>>> From Elizabeth Kolbert, New Yorker Magazine, November 28, 2022

Climate surprises keep popping up. Starting in 2007, for example, methane levels in the atmosphere took an unexpected jump.

Methane is a far more potent greenhouse gas than CO2, so scientists were alarmed. They eventually !gured out, on the basis of the methane’s isotopic composition, that the source of the increase couldn’t be fossil-fuel production, even though oil and gas wells often leak methane into the air. Instead, the culprit must be microbes, either the sort that live in a marsh or the sort that live in a cow’s gut.

Recent research suggests that the bulk of the extra methane is coming from the Sudd, a huge wetland in South Sudan, and that warming itself is responsible for the uptick in microbial activity. If that’s the case, then a spiral is likely to ensue: more methane will produce more warming, which will produce yet more methane, and so on. (Like a tipping point?)

How many positive feedback loops like this have already been —or are about to be— initiated? Despite the best efforts of climate modellers, no one can say. Several enormous Antarctic glaciers rest on bedrock that’s below sea level; as these glaciers retreat, water is starting to seep underneath and to melt them from the bottom up.

This, in turn, is leading to more retreat and still more melting. One retreating glacier, formally known as Thwaites, has informally become known as the Doomsday Glacier. A recent paper in Science observed that the “eventual collapse” of Thwaites, which is the size of Florida, “may already be inevitable.”

Even after global emissions reach net zero— whenever that is— ice sheets will continue to melt and sea levels to rise for hundreds or perhaps thousands of years.

All the way back in 1965, the authors of one of the first reports on global warming, which was not yet known as global warming, warned that humanity was “unwittingly conducting a vast geophysical experiment.” As Marcia Bjornerud, a geologist at Lawrence University, has written, the irony of our oversized impact on the Earth is that we have “put Nature firmly back in charge, with a still-unpublished set of rules we will simply have to guess at.”

By Chris Mooney and Simon Ducroquet, Washington Post, Updated January 21, 2023

This is a story about a curious seal, a wayward robot and a gigantic climate change disaster that may be waiting to happen.

Scientists tagged a southern elephant seal on the island of Kerguelen, an extraordinarily remote spot in the far southern Indian Ocean, in 2011. The seal was a male close to 11 feet long weighing nearly 1,800 pounds, and they fitted his head with an ocean sensor, a device that these massive seals barely notice but that have proved vital to scientific research.

Elephant seals like this one swim more than 1,500 miles south from Kerguelen to Antarctica, where they often forage on the seafloor, diving to depths that can exceed a mile below the surface. As summer in the Southern Hemisphere peaked, the seal made a standard Antarctic journey, but then went in an unusual direction.

In March 2011, he appeared just offshore from a vast oceanfront glacier called Denman, where elephant seals are not generally known to go. He dived into a deep trough in the ocean bed, roughly half a mile below the surface. And that is when something striking happened: He provided an early bit of evidence that Denman Glacier could be a major threat to global coastlines.

The seal swam through unusually warm water, just below the freezing point, but in the Antarctic, that is warm. Given its salt content and the extreme depths and pressures involved — in some regions Denman Glacier rests on a seafloor that is over a mile deep — such warm water can destroy large amounts of ice. And it certainly could have been doing so at Denman.

Yet scientists do not appear to have seen the significance of the seal data. Back then, Denman had not received much scientific attention. It did not help that the glacier is extraordinarily difficult to study directly. It lies between the two Antarctic research bases of Australia. The logistics are challenging for a voyage from either side, especially as the glacier is often locked in by extensive sea ice.

Researchers had already observed that the glacier was losing some of its mass, which is a worrying sign. They also knew something else: Denman serves as a potential doorway into a region of extremely deep and thick ice, even for Antarctica.

With Denman and several other neighboring glaciers in place, the doorway remains closed. Opening it would allow warmer ocean water to start eating away at this thick ice, leading to gradual melt and eventually, a massive influx of new water into the ocean. That would have the potential to unleash over 15 feet of sea level rise, remaking every coastline in the world. So the scientists flew a few planes over Denman and watched with their satellites. And they waited.

…… enter the robot …. see the full article …

SOURCE ~ https://www.washingtonpost.com/climate-environment/2023/01/18/climate-change-glacier-antarctica/?location=alert