Antarctica’s melting glaciers have contributed to global sea level rise for decades, but a new study from the Potsdam Institute for Climate Impact Research says the rate of glacial melt could accelerate in coming years.
If greenhouse gas emissions continue to increase, researchers predict discharge from Antarctic ice alone will raise sea levels by up to 14.6 inches (37 cm). However, they also admit that there is a wide range of possibilities, and glacial melt could contribute as little as one centimeter.
“This is a big range, which is exactly why we call it a risk,” says the study’s lead author Anders Levermann. “Science needs to be clear about the uncertainty so that decision-makers at the coast and in coastal megacities can consider the implications in their planning processes.”
When the waters rise, the megacities that will suffer the greatest amount of flooding and property damage (and trigger a wave of refugees) are New York City, Miami and Guangzhou, China. Cities that are already at risk include Tokyo, New Orleans and Amsterdam, and in 50 years they will be joined by Calcutta, Shanghai, Mumbai and Ho Chi Minh City. With so many cities and so many people potentially at risk, finding the exact number between one and thirty-seven centimeters is imperative.
The window for countries to plan for that risk is narrowing. The Potsdam Institute asserts that their projections for glacial contributions to sea level rise are “significantly higher” than the already increased levels cited in the UN’s Intergovernmental Panel on Climate Change.
“Earlier research indicated that Antarctica would become important in the long term,” says Levermann. “But pulling together all the evidence, it seems that Antarctica could become the dominant cause of sea level rise much sooner.”
Two recent studies have already confirmed that six major glaciers in West Antarctica have reached a point of “irreversible retreat.” Even if greenhouse gas emissions were to cease, it would not stop the thawing process.
Approximately 69 percent of current glacial melt can be attributed to anthropogenic, or man-made causes, specifically the burning of fossil fuels, according to a study published Thursday in the journal Science. “Glaciers without human impacts would still be melting,” says the study’s lead author Ben Marzeion, but not nearly as quickly. An international inventory of glacial measurements carried out by Marzeion and his fellow researchers found that the thaw has been increasing since the ‘90s.
Marzeion, a climate scientists with the University of Innsbruck in Austria, was driven to the research after noting how frequently pictures of glaciers from the 1850s are compared to pictures in the 2000s as proof of global warming. “Everybody is using [these photos],” Marzeion told Climate Central. “But nobody actually looked at whether it’s justified to do this.”
His team discovered that, while only 25 percent of glacial melt could be attributed to anthropogenic causes between the 1850s and the 1980s, that percentage more than doubled between 1991 and 2010.
Marzeion found that climate change advocates were more than justified in using before and after photographs of glaciers and disappearing snowpacks. Unfortunately, with the proof comes the conclusion that this process cannot be stopped. “It’s sort of sad that we can’t do anything about it, because the glaciers are going to melt no matter what we do over the next 50 years or so,” he said.