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From the ice caps to the glaciers of Europe, Asia and South America, global warming is melting the planet’s ice faster than ever and accelerating the flooding of the world’s coasts.
New research shows that the annual melt rate increased from 0.8 trillion tons in the 1990s to 1.3 trillion tons in 2017, and has accelerated the most in the places with the most ice: the shelves and layers of ice. Greenland ice and Antarctica.
Those massive land and sea ice systems are melting as fast as the worst climate scenarios from major global weather reports, he said. Thomas slater, co-author of the new study in The Cryosphere that measured melting from 1994 to 2017, which covers a period when each decade was warmer than the previous one and also includes the 20 warmest years on record.
It is one of the first studies to collect estimates of all the ice on the planet, except for permafrost. Previous research has typically focused on individual elements of the cryosphere, such as glaciers, sea ice or ice shelves, he said. Ruth Mottram, a climate scientist with the Danish Meteorological Institute, who was not involved in the new study.
Slater said the evaluation of the data did not lull him to sleep at the staggering amount of ice that melted during the study period, describing it as a mountain taller than Mount Everest and covering Manhattan enough to raise global sea level. 1.4 inches in 23 years.
“The ice sheets are now following the worst climate warming scenarios established by the Intergovernmental Panel on Climate Change,” he said. “Sea level rise on this scale will have very serious impacts on coastal communities this century.”
Sea level has risen about eight to ten inches since 1880. It is likely to rise by at least a foot and could rise as much as eight feet by 2100, according to recent estimates from the National Oceanic and Atmospheric Administration. The Intergovernmental Panel on Climate Change estimates an increase of between two and three feet by 2100 if global warming stays well below two degrees Celsius (3.6 degrees Fahrenheit), or three to five feet if temperatures exceed that.
Sea level rise is a matter of life and death
Getting the projections correct is critical because, by some estimates, every inch of sea level rise threatens to displace around 1 million people from cities and low-lying farmlands. For cities near sea level, knowing whether the ocean will rise two feet or five feet is literally a billion dollar question and, at worst, a question of survival and dislocation.
Mottram said the new findings do not necessarily mean that global sea level will continue to follow the most dire predictions because there are other factors involved, primarily the expansion of the oceans as they warm, which until recently accounted for most of the rise in the world. sea level. that has been measured.
Several studies show an “acceleration in sea level rise in the past five years, from about 1.2 inches per decade to a rate of 1.9 inches per decade,” he said. “We know it varies a lot from year to year and things like El Niño, or if Greenland has a hot summer, can have an effect. But the deeper ocean is also warming and that also continues to add thermal expansion. So the rise in sea level will continue for centuries. “
Analyzing the melting of polar and glacial ice at the same time helps to distinguish how much of the melting is caused by atmospheric warming compared to the heat of the ocean. The atmosphere reacts relatively quickly to changes in its concentrations of greenhouse gases, which warm the Earth, and to other pollutants that can reflect heat away from the planet. The oceans respond much more slowly to the drivers of global warming. Understanding those dynamics sharpens projections for sea level rise, he said.
University of Liège ice researcher Xavier Fettweis, who was not involved in the research, said the findings help reduce uncertainties around melting ice and rising sea levels by adding new information from satellites to update data sets used in previous studies.
It covers a key period for the planet’s climate because the large increase in polar ice melt began during the 1990s, “probably because we have exceeded the temperature threshold of 0 degrees Celsius (32 degrees Fahrenheit) in large areas. The cryosphere is starting to change as soon as this temperature threshold is reached, ”he said. Climate models dating back to 1950 show conclusively that “there was no significant and lasting change in melting” prior to the 1990s.
The numbers are huge and terrifying
Regardless of how you measure it, global ice loss figures add to problems, the glaciologist said. Heidi sevestre, who did not participate in the study.
The numbers are “getting so huge and so astronomical, what else do we need to act on?” she asked. “We need to understand the human cost and the economic cost of each ton of ice. I think if we knew the true cost of every ton of ice that is lost, if people knew this, we would stop immediately. ”
Sevestre worries that lawmakers see the accelerating melting of the world’s ice as an opportunity rather than a threat.
“Last week I had the opportunity to speak with the French Senate, and they see the Arctic as a big cake that they want to get a part of, the fishing and the energy,” he said. “They think it’s going to be an Eldorado for fishing, but as we lose the sea ice and the Arctic Ocean becomes more acidic, that definitely won’t happen.”
In his presentation to the Senate, he emphasized that a rise in sea level in the worst case scenario means that “we are going to lose the main French port, and we are going to lose the cold water from the glaciers that we need to cool our nuclear energy. Energy plants.”
“So many studies have been done on ice loss and sea level rise that it’s easy to get stunned by the numbers,” he said. “But of course, they should never feel normal, and the fact that climate change is accelerating should never feel normal.”
The new research is another warning that warming above 1.5 degrees Celsius (2.7 degrees Fahrenheit) will push the world’s ice past a tipping point, causing irreversible melting and destabilization of layers of ice. ice, he said.
“We must act as quickly as possible to avoid going beyond these thresholds,” Sevestre said. “We are in uncharted territory. We can’t afford to lose another ton of ice. We have no other options. “
Bob berwyn
Freelancer
Bob Berwyn, an Austria-based freelance reporter who has covered climate science and international climate policy for more than a decade. Previously, he reported on the environment, endangered species, and public lands for various Colorado newspapers, and also worked as an editor and assistant editor for community newspapers in the Colorado Rocky Mountains.
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