Climate is making the Doomsday Glacier in Antarctica melting faster than scientists thought
Antarctica’s “doomsday glacier” is melting faster than we thought thanks to climate change. The glacier has gotten its nickname because of how much ice it has and how much seas could rise if it all melts, is melting faster because of warmer sea water passing below it. Thwaites is on Antarctica’s western half, east of the jutting Antarctic Peninsula, which used to be the area scientists worried most about.
For years, experts have worried about the possible demise of the Thwaites, whether by ocean water melting it from below, the glacier unmooring from its attachment to the seabed, or the ice mass cracking and breaking apart. Using satellites and a technique called radar interferometry to track changes in surface elevation, the team found that the glacier appeared to be lifting several centimeters as pressurized tide water moved below it across many miles, further inland than previously thought. There are places where the water is almost at the pressure of the overlying ice, so just a little more pressure is needed to push up the ice.
The water is then squeezed enough to jack up a column of more than half a mile of ice. Warmer seawater working its way under the glacier may help explain the rapid, past, and present changes in ice sheet mass and the slower changes replicated by ice sheet models. Pressurized seawater will create a vigorous melt that will further imperil the glacier. Thwaites is the most unstable place in the Antarctic and contains the equivalent of 60 centimeters of sea level rise.
The worry is that we are underestimating the speed that the glacier is changing, which would be devastating for coastal communities around the world.
It is still not clear how much time is left before the ocean water’s damage to the glacier is irreversible, but hopefully the discovery will lead to more accurate models. It will take many decades, not centuries, for the Thwaites to fully melt. Part of the answer also depends on whether our climate keeps getting warmer or not, which depends completely on us and how we manage the planet.
And for the first time, there is visible evidence that shows warm seawater pumping underneath the glacier. The Thwaites, part of the vast West Antarctic Ice Sheet, is one of the world’s fastest-changing and most unstable glaciers. It has been studied for years as an indicator of human-caused climate change. Study results also suggest the Antarctic Ice Sheet is more vulnerable to a warming ocean than previously thought, and, worryingly, may require a reassessment of sea-level rise projections.
To conduct the study, scientists used high-resolution satellite radar data to find evidence of the intrusion of warm, high-pressure seawater many miles beneath the grounded ice of Thwaites. There is much more seawater flowing into the glacier than had been previously thought. These intrusions make the glacier more sensitive to ocean warming, and more likely to fall apart as the ocean gets warmer.
Future projections of global sea-level rise will have to include this new data.
The projections will go up. As it melts, Thwaites could cause ocean levels to rise as much as 2 feet. But the glacier is also a natural dam to other ice in West Antarctica. If that ice is released into the oceans, levels could rise 10 feet. Such a rise would put many of the world’s coastal cities underwater. It will gravely impact populations in many low-lying areas like Vancouver, Florida, Bangladesh, and low-lying Pacific islands, such as Tuvalu and the Marshall Islands.
In August 2020, new research has suggested that climate change is the culprit that Woolly rhinos went extinct at the end of the last ice age in Siberia about 14,000 years ago. And now ancient DNA is helping to shed light on what really happened to them and other large mammals. Previously, it was believed that humans hunted these giant animals as they spread across the globe.
It is really amazing that the researchers can read the DNA sequences, even the entire genomes, from these long-extinct animals. It is a bit like having a time machine where they can travel back through time and study evolutionary change as it is happening in real-time. Given the climate where these animals lived and died, the cold conditions helped preserve their DNA.
While obtaining high quality DNA is difficult, the researchers are lucky to work on specimens that have been preserved in the permafrost for thousands of years.
In a way, it is like opening a freezer that was closed during the last Ice Age. Rather than disappearing due to overhunting by early humans, woolly rhino populations actually seemed to thrive and remain incredibly diverse before they went extinct. Recent research has also shifted back the timeline for humans living in Siberia. Originally, it was believed humans arrived between 14,000 and 15,000 years ago.
New evidence has pushed human occupation back to sites that are at least 30,000 years old, so the arrival of humans no longer coincides with the demise of woolly rhinos. Instead, the DNA the researchers studied revealed more of a population boom for woolly rhinos during that time. The DNA was retrieved from tissue, bone, and hair samples from 14 woolly rhino specimens that lived across Siberia.
The scientists were able to determine information about the population sizes and genetic diversity of these woolly rhinos stretching back for tens of thousands of years before they went extinct. The researchers were surprised to discover that woolly rhinos had a much higher genetic diversity than any living rhino, woolly mammoths, or even modern humans. The woolly rhinos also appeared to go extinct suddenly, rather than gradually, and did not experience much inbreeding.
Inbreeding tends to increase as populations decline, and it occurred in the last woolly mammoths before they went extinct.
The researchers also found genetic mutations in the woolly rhino DNA that helped them adapt to life in the bitterly cold weather of the last ice age, including a receptor in the skin that could sense temperature variations. Woolly mammoths also had this adaptation. About 29,000 years ago, the woolly rhino population swelled as the ice age intensified and remained stable with little inbreeding.
The data provided by the DNA followed the woolly rhino population until about 18,500 years ago, which was about 4,500 years before they went extinct. This tells the researchers that the cause for their extinction occurred during that 4,500-year gap. A sudden but brief period of warming temperatures occurred toward the end of the last ice age. This event, called the Bølling-Allerød interstadial, happened between 12,890 and 14,690 years ago.
The temperature change was fast. Some records from ice cores taken on Greenland suggest an increase in temperature by 18 degrees Fahrenheit, possibly within as little as a few decades. The large grasslands where the woolly rhinos roamed, called a steppe environment, would have been replaced by trees and shrubs in response to the warming as well. Like woolly mammoths, woolly rhinos were covered in thick fur and perfectly suited to their cold environment, grazing across the Siberian tundra.
Both had adaptations that helped them thrive during the last ice age.
But mammoths were about three times bigger, had a more flexible diet, and lived in matriarchal herds. The woolly rhinos were likely more solitary. And the woolly mammoths did not experience an increase in population size as the woolly rhinos did 29,000 years ago. Now the researchers want to study DNA from woolly rhinos that lived during those last 4,500 years before they went extinct.
The scientists also want to investigate other large animals that had adapted to such cold conditions to see how they were affected by a warmer and less stable climate. This includes cave lions, wolves, mammoths, horses, and steppe bison. The researchers are coming away from the idea of humans taking over everything as soon as they come into an environment.
Although they can not rule out human involvement, the researchers suggest that the woolly rhinoceros’ extinction was more likely related to climate change.
The climate science community is mourning the loss of a pioneering climate scientist and glaciologist, Konrad Steffen.
Steffen apparently fell to his death in a deep opening in the ice called a crevasse while doing research in Western Greenland. With nearly 15,000 academic citations to Steffen’s name, he dedicated his life to studying the rapidly melting ice sheets in Greenland and Antarctica. Ironically, it was the perils created by melting around Swiss Camp in Greenland, a research outpost Steffen founded in 1990, that claimed his life.
Jason Box, a well-known ice climatologist at the Geological Survey of Denmark and Greenland, had spent many years working alongside Steffen and was with him right before he disappeared. Box says the snowy, windy weather at the time was disorienting. Steffen ultimately went beyond the safety perimeter in low visibility, windy conditions. Steffen fell into a water based crevasse while the rest of the team were working nearby, unaware.
The last thing Steffen said was that he was going to look at data. The team organized a lengthy search and eventually found evidence in the thin ice. The team found a 2.5 meter long busted through hole in the 3 cm thick floor of the crevasse 8 meters down. Since Steffen was not found, he might be 8 meters down in the water. Steffen was like a father to Box.
In a tweet citing Steffen’s dedication to his craft, Box invoked a quote from Abraham Lincoln, “It is for us the living to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced.”
This sentiment was shared widely by the science community. The Swiss Polar Institute, where Steffen served as scientific director, said in a statement on its website, “We will deeply miss Konrad Steffen, but are committed to continuing his mission towards making a contribution, big or small, to create a difference.” It included a link to a video about Steffen and his work.
The statement went on to say, “We lost a wonderful person and true friend way too early.” An outpouring of memories on social media paid tribute to Steffen’s kindness, warmth, and generosity. Steffen started his career in 1977 when he graduated from ETH Zurich, an institute with which he still collaborated. With Steffen’s death, ETH has lost a uniquely kind and committed colleague.
Through the years Steffen held many leading positions in climate science. Former United States vice president and Nobel laureate for his work in climate change, Al Gore, praised the influence Steffen has had. Steffen’s renowned work as a glaciologist has been instrumental in the world’s deepened understanding of the climate crisis.