Sea level rise as Earth’s ice melts is a prophecy that began to come true long ago, at the dawn of industrial civilization when humans began pumping massive amounts of greenhouse gases into the atmosphere. However, the timeline for sea-level rise is not yet fully understood, and we don’t really know how close our coastal cities are to facing devastation from accompanying floods or rising tides.
Now, a new pair of studies is revealing one possible – and potentially probable – pathway in which sea-level rise could play out on Earth, inundating our coastal cities.
The first study — published in Nature Geoscience — involved Thwaites Glacier, a natural wonder in West Antarctica roughly the size of Florida. Because it is the largest glacier in the world, it has been dubbed the “Doomsday Glacier” – because if it collapsed, the subsequent rise in global sea levels would send millions out of their homes. Researchers have already determined that Thwaites glacier is melting at dangerous levels, and the new study reveals the severity of the problem.
“Our greenhouse gas emissions are hitting the climate system with a metaphorical hammer.”
The researchers studied the footprints on the sea floor to confirm the movements of the Thwaites glacier over the past century. Hence, they determined that the glacier shrank by about 1.3 miles each year during that period. That’s twice the rate of shrinkage we’re seeing today, which means that while the current rate of melt is not unprecedented, the ice sheet is already so capable of melting that the Thwaites glacier itself would collapse. If all the ice upstream in the Thwaites Glacier’s drainage basin melted, global sea level would rise by more than two feet.
Anna Wolin, professor of physical oceanography at the Swedish Gothenburg university and co-author of the study told NBC News. “But you could also say it’s bad news, because it could happen again.”
The second study – published in the journal Nature Climate Change – was led by Dr Jason Box, a glaciologist at the Geological Survey of Denmark and Greenland. It found that the rapidly melting Greenland ice sheet would raise global sea levels by at least 10.6 inches (27 cm). That’s twice as fast as experts previously thought, and it’s fed by “zombie ice”, or smaller ice bodies still attached to larger ice bodies but doomed to melt because they are not constantly fed on ice by a glacier.
As study co-author Dr. William Colgan explained to the Associated Press, “It’s dead ice. It will melt and disappear from the ice sheet. This ice has been sent into the ocean, no matter what our climate (emissions) scenario takes now.”
This sets the new study in contrast to the Intergovernmental Panel on Climate Change (IPCC), a United Nations body focused on combating climate change. The Intergovernmental Panel on Climate Change predicted last year that melting ice in Greenland will only raise sea levels by 2 to 5 inches by 2100.
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Jim Hansen, director of the Climate Science, Awareness and Solutions Program at Columbia University’s Earth Institute, told Salon by email that the recent research papers are “a growing response” from scientists “to fight the scientific conservatism established by the IPCC.”
“After failing for decades to properly warn the public and provide little advice on needed policies, the IPCC continues to pretend that it is possible to keep global warming below 1.5°C with emissions-reduction targets and targets,” Hansen explained. “Climatology tells us that we are already at dangerous levels of greenhouse gases that will have consequences beyond 10 inches of sea level rise.”
Sarah Braal, an associate professor of political science at Syracuse University who specializes in environmental policy, environmental policy, climate change, and energy, also told Salon that the new studies indicate that “our previous models of climate change impacts have likely underestimated the magnitude and timeline of major climate disasters such as sea level rise.”
Dr. William Sweet, a scientist with the National Oceanic and Atmospheric Administration (NOAA), referred Salon to the agency’s sea-level rise technical report. The report, released in February, appears to reinforce the concerns raised by the last two studies. The NOAA report predicts that sea level along the coastline of the United States will rise 10 to 12 inches within the next 30 years, although this is just an average number. Along the East Coast, the height is expected to be 10 to 14 inches; For the West Coast, 4 to 8 inches are expected; For the Gulf Coast, they are expected to range in size from 14 to 18 inches.
Needless to say, major cities from San Francisco to New York City can expect to be severely flooded.
“Sea level rise is already affecting us, here and now, and will continue to increase dramatically over the coming decades.”
“These studies provide additional evidence about possible future sea-level rises that the public should be aware of,” Sweet wrote to Salon. “Sea level rise is already affecting us, here and now, and will continue to increase dramatically over the coming decades.” In the words of Dr. Ken Caldera, chief scientist emeritus at the Carnegie Institution for Science, “These kinds of studies are not surprising to people who have been studying how climate changed in Earth’s geological past.”
“Studies of climate change in the geological past paint a picture of a world that could change much more quickly and with much more force than most recent climate models have predicted,” Caldera said. “Our greenhouse gas emissions are hitting the climate system with a metaphorical hammer. We have to expect the unexpected. If we think the expected is all we have to worry about, we live in a fantasy land. We are interfering with a system far more complex than any of our models. We can be confident that many things will happen that we will not be able to predict.”
Some scholars have been critical of how studies are presented to the public through the media.
Dr. Michael E. Mann, Distinguished Professor of Atmospheric Sciences at Penn State University, wrote for Salon about the new studies, which he discussed with “one of the world’s leading glaciologists,” Dr. Richard Alley. They argued that, despite the “somewhat breathless headline in the NBC news article” (“doomsday glacier ‘could melt faster than previously thought’), the new study doesn’t change anything fundamental. About what we know about Thwaites Glacier.
Mann explained, “As Richard told me, ‘the information doesn’t really support any acoustic signal about the instability or stability of the ice sheet, with no fundamental change in our understanding.’” To be clear, our current understanding is cause for concern enough. It suggests that we may be dangerously close to locking in enough warming that we lose a significant portion of the West Antarctic ice sheet, enough ice to give us 10 feet or more of sea level rise eventually, but we knew that entry. This study does not change our understanding in this regard.
Regarding the Greenland study, Mann once again urged to be wary of the media that covers it.
“It is a useful study and the main conclusion – that there may be a committed sea-level rise from the Greenland ice sheet – seems entirely plausible,” Mann wrote. But here, too, some of the coverage has been misleading. The authors (as noted in the Associated Press article) suggest this will happen within this century, but they don’t actually provide any support for it, so some public comment seems to lag behind what their science shows in Indeed “.
Dr. Kevin Trenberth, part of the Department of Climate Analysis at the US National Center for Atmospheric Research, has been highly critical of how the reports are publicly discussed.
“The discourse on both studies is misleading at best and often wrong,” Trenberth wrote for Salon. “There are dire consequences for land ice melt in relation to sea level rise. The Greenland study does not put a timeline for ice loss: it is certainly not this century but perhaps [two] Centuries. So it’s really a big long-term concern but a lot of the rhetoric in the reports is wrong.”
He added, “Thwaites’ article is interesting in providing a mechanism for increased glacier flow. It is not much clear what it means for sea level rise and on the time scale. Again, it is a major long-term concern but…and there are many but “.
Trenberth stated that some of the ice in question is already floating and therefore will not affect sea level when it melts. It also doesn’t take into account ‘other things that are going in other directions, like increasing snowfall over Antarctica causing water to be pushed out of the ocean. So people should be concerned and welcome increased information and understanding, but there are many other reasons why’ to more concerned.”
Trenberth cited Pakistan as a real-life example of climate change-related flood proof, writing that “large-scale flooding in Pakistan is partly the result of torrential rains but also sea level rise that prevents land water from draining away.”
Some of the scientists who spoke to Salon also discussed potential policy solutions to the climate change problems facing humanity.
“Policy makers and political leaders need to take their notes and step up and accelerate their responses to the climate threat, to give us the best possible chance of avoiding the worst effects of climate change,” Brall said. “Some of these changes are going to happen whether we cut emissions or not, so we also need to adapt to changes that have already been ‘absorbed’, so to speak. At the same time, we must not let stories/research like this leave us hopeless. Whatever we do. Reducing greenhouse gas emissions will help, and the difference between some warming, and a lot of warming, is enormous in terms of the scale and extent of the damage.”
Hansen, for his part, specifically suggested increasing prices for carbon products, noting that “economics tells us that we haven’t started to tackle it until we put a steadily rising price on carbon.” This does not happen, he said, because “our politicians don’t have the guts for it, although there are ways to do it (carbon fees and profits) that benefit most people economically. They would rather support this or that, which would have little impact on global emissions.”
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