Sea level rise: Glacial and Ice sheet Melt
Sea levels are rising because of human caused global heating from the burning of coal, oil, and natural gas. Rising temperatures are causing glaciers and ice sheets to melt and seawater to warm and expand. Oceans act as one of Earth’s main carbon sinks, absorbing 31% of global emissions, but as they warm, they no longer act as a sink and instead begin to emit carbon.
Ice sheets and glaciers act as Earth’s air conditioners, reflecting sunlight back into space (the albedo effect) and keep ocean waters cool. As global temperatures rise, ice sheets and glaciers are melting, exposing the dark ocean water beneath. This triggers a positive feedback loop, with dark waters absorbing heat, thus accelerating ocean heating and increasing glacial and ice sheet melt.
As sea levels rise, coastal communities are in danger of flooding and damage to infrastructure that, in time, will force people to relocate.
Read a roundup of the headlines:
“The Greenland Ice Sheet covers 1.7 million square kilometers (660,200 square miles) in the Arctic. If it melts entirely, global sea level would rise about 7 meters (23 feet), but scientists aren't sure how quickly the ice sheet could melt. Modeling tipping points, which are critical thresholds where a system behavior irreversibly changes, helps researchers find out when that melt might occur.
Based in part on carbon emissions, a new study using simulations identified two tipping pointsfor the Greenland Ice Sheet: releasing 1000 gigatons of carbon into the atmosphere will cause the southern portion of the ice sheet to melt; about 2500 gigatons of carbon means permanent loss of nearly the entire ice sheet.
Having emitted about 500 gigatons of carbon, we're about halfway to the first tipping point.”
Phys.org, The Greenland Ice Sheet is close to a melting point of no return, says new study
”Melting ice around Antarctica will cause a rapid slowdown of a major global deep ocean current by 2050 that could alter the world’s climate for centuries and accelerate sea level rise, according to scientists behind new research.
The research suggests if greenhouse gas emissions continue at today’s levels, the current in the deepest parts of the ocean could slow down by 40% in only three decades.
This, the scientists said, could generate a cascade of impacts that could push up sea levels, alter weather patterns and starve marine life of a vital source of nutrients.”
The Guardian, Melting Antarctic ice predicted to cause rapid slowdown of deep ocean current by 2050
“A large glacier in Antarctica that could raise sea
levels several feet is disintegrating faster than last predicted, according to a new study published Monday in the journal Nature Geoscience.
The Thwaites Glacier — dubbed the “doomsday glacier” because scientists estimate that without it and its supporting ice shelves, sea levels could rise more than 3 to 10 feet — lies in the western part of the continent. After recently mapping it in high-resolution, a group of international researchers found that the glacial expanse experienced a phase of “rapid retreat” sometime in the past two centuries — over a duration of less than six months.
According to a news release accompanying the study, researchers concluded that the glacier had “lost contact with a seabed ridge” and is now retreating at a speed of 1.3 miles per year — a rate double what they predicted between 2011 and 2019.”
Washington Post, A ‘doomsday glacier’ the size of Florida is disintegrating faster than thought
“In a new study, scientists say Earth’s oceans are already locked into nearly 10.8 inches of sea-level rise from Greenland’s melting ice sheet, even if humans stopped emitting planet-warming greenhouse gases today.
And if our burning of fossil fuels continues, the total sea-level rise from the massive island’s melting ice could be much higher, researchers warn.
In the paper, published Monday in the journal Nature Climate Change, the researchers examined the snow line, or the boundary between a higher-elevation section of Greenland’s ice sheet where snow and ice accumulates and a lower section where snow melts, writes USA Today’s Dinah Voyles Pulver. Currently, the melting area is growing larger, and the ice accumulation area is shrinking.
“We have caused the ice sheet to go out of equilibrium,” David Bahr, a co-author of the study and a glaciologist at the University of Colorado Boulder, tells USA Today. “We’re melting it faster than the ice can move downstream and replenish areas that are melting.’”
Smithsonian, Melting Greenland Ice Sheet Will Cause at Least Ten Inches of Sea-Level Rise, Study Finds
“A new study shows that the Arctic has warmed nearly four times faster than the rest of the world over the past 43 years. This means the Arctic is on average around 3℃ warmer than it was in 1980.
This is alarming, because the Arctic contains sensitive and delicately balanced climate components that, if pushed too hard, will respond with global consequences.
When covered with sea ice, the Arctic Ocean acts like a large reflective blanket, reducing the absorption of solar radiation. As the sea ice melts, absorption rates increase, resulting in a positive feedback loop where the rapid pace of ocean warming further amplifies sea ice melt, contributing to even faster ocean warming.
This feedback loop is largely responsible for what is known as Arctic amplification, and is the explanation for why the Arctic is warming so much more than the rest of the planet.”
PBS, The Arctic is warming nearly four times faster than the rest of the world
“The fate of the world’s biggest ice sheet rests in the hands of humanity, a new analysis has shown. If global heating is limited to 2C, the vast East Antarctic ice sheet should remain stable, but if the climate crisis drives temperatures higher, melting could drive up sea level by many metres.
The East Antarctic ice sheet (EAIS) holds the vast majority of Earth’s glacier ice – sea levels would rise by 52 metres if the entire sheet melted over future millennia. It is thought to be stable, but is now showing signs of vulnerability, and certain climate conditions in the nearer future could cause melting that would increase sea levels by up to 5 metres by 2500, the scientists said.”
The Guardian, Fate of ‘sleeping giant’ East Antarctic ice sheet ‘in our hands’ – study
“The nation's coasts are in trouble. After a year of record-breaking coastal flooding, a new report released by the National Oceanic and Atmospheric Administration found that it's going to get more frequent, more intense and more widespread across the U.S.
High-tide flooding, otherwise known as "king tides" or "sunny day" flooding, has already increased in frequency over the years as sea levels continue to rise. According to NOAA, it typically occurs when tides rise about 2 feet above the daily average and ocean water starts to cascade over streets and bubble up from storm drains.
This kind of flooding used to really only happen during storms. But now, NOAA says it can happen just from a full moon or a shift in prevailing winds or currents. Decades of sea level rise is to blame and the situation has only been driven by climate change.”
“Imagine a world where nearly all our coastal cities are underwater. That’s what’s in store if climate change continues at its current pace, threatening to raise sea levels and create storm surges strong enough to drown out major metropolises and drive out half of the global population that now lives close to the water.
Sea levels are rising at an alarming rate, with projections for some coastal cities as high as 10 feet by the end of the century. Places like Rotterdam, Jakarta and Boston are not sitting idle.”
The Groudtruth Project, Cities Underwater
More reading:
The Guardian, Ice sheets can collapse at 600 metres a day, far faster than feared, study finds
USA Today, Fact check: Human-driven global warming increased Larsen ice shelf melt
CNN, Antarctic sea ice hit record lows again. Scientists wonder if it’s ‘the beginning of the end’
The Washington Post, Greenland temperatures surge up to 50 degrees above normal, setting records
BBC, Why East Antarctica is a 'sleeping giant' of sea level rise
Flagler Live, Greenland and Antarctica Cracking