Increasing global sea levels is being caused by ice streaming off of the glaciers. According to new results published in Nature, models have underestimated how much ice will be lost. Its contribution to sea-level rise will be more pronounced.
According to the new study, the ice stream will add between 13,5 and 15,5mm to the rising sea level. The contribution of the ice sheet in the last 50 years is equivalent to this. The research was done by researchers from several countries.
Shfaqat Abbas Khan, the first author of the book, said that the previous projections of ice loss were vastly underestimated.
A lot is happening at the front of the ice sheet, which is easily accessible, and that's what the models are focused on.
More than 200 km of ice is lost inland.
The study is based on data collected from a network of preciseGPS stations that reach as far as 200 km inland on the Northeast Greenland Ice Stream. High-resolution numerical modeling and surface-elevation data were combined with the gps data.
The data shows that what we see at the front reaches far back into the ice sheet.
The basin is getting thinner and the surface speed is increasing. We think that the glaciers will retreat further inland over the next decades and centuries. It is hard to imagine how this retreat could be stopped.
Sea levels are rising.
The floating extensions of the glacier collapsed in 2012 after 10 years of melting. The glaciers have retreated even though the winter and summer have been particularly cold. The ice sheet is not regenerating enough because it is a so-calledArctic desert. It's difficult to estimate how much ice is lost and how far into the ice sheet the process takes. The ability to make accurate projections is hampered by the fact that the ice sheet's interior moves less than one meter a year.
"It is truly amazing that we are able to detect a subtle speed change from high-precisionGPS data, which ultimately, when combined with a model of ice flow, inform us on how the glacier slides on its bed."
There is a chance that what we see in northeast Greenland is happening in other parts of the ice sheet. Near the margin, many glaciers have been speeding up and slowing down. The location of this acceleration can be detected with the help of gps data. Current models suggest a smaller contribution from ice dynamics to the mass loss of Greenland.
A large portion of the floating sections became disconnected when the ice front retreated. It is likely that the estimates of 22–98 cm global sea level rise will need to be revised upwards due to more precise observations of ice velocity.
Eric Rignot is a professor of Earth system science at the University of California, Irvine.
Data collected in the vast interior of ice sheets helps us better represent the physical processes included in numerical models and in turn provides more realistic projections of global sea-level rise.
Shfaqat Abbas Khan describes extensive inland thinning and speed-up of the North-East Greenland Ice Stream. The article can be found at www.nature.com/articles/s.
Journal information: Nature
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