The ‘hot spot’ in the mantle of the Earth that feeds the active volcanoes of Iceland has been playing a trick on scientists trying to measure how much ice is melting in Greenland because this island really loses 7.6 percent icy layer over what had been calculated.
This follows from an international study conducted by researchers at the Technical Universities of Denmark and Copenhagen (Denmark); Bristol (United Kingdom); Colorado, Buffalo, Alaska Fairbanks, Cornell and Ohio State (United States); Utrecht (Netherlands), and Luxembourg, and the German Research Centre of Sciences and the Helmholtz Centre for Polar and Marine Research (Germany).
The study, published in the journal Science Advances’ says that this’ hot spot ‘softened mantle rock beneath Greenland in the past so distorted loss calculations ice frost layer of this island, which made underestimating the merger at about 20 gigatons (20 million metric tons) each year.
That means that Greenland did not lose the nearly 2,000 gigatons of ice 500 between 2003 and 2013 that scientists thought, but almost 2,000 gigatons 700, representing a 7.6% increase, according to Michael Bevis, State University of Ohio and co-author of the study.
“It’s a fairly modest correction,” says Bevis, an expert in geodynamics, professor of Earth Sciences at the university and leader of GNET (Red GPS Greenland, a project funded by Denmark, the United States and Luxembourg), who adds: ” It does not change much our estimates of the total mass loss across Greenland, but brings a more meaningful to our understanding of where the ice loses ice and where is happening now “change.
GNET team used GPS stations in Greenland to measure the elevation of the crust along the coast and discovered that two of them rose faster than standard models had predicted.
Ice Age
Bevis explained that the Earth’s crust in that part of the planet is moving slowly northwest and parts of Greenland spent 40 million years ago on a partially molten rock column especially hot now lies beneath Iceland. That point softened the rock in its path, thereby reducing the viscosity of the bedrock far below the surface of the east coast of Greenland.
During the last ice age, the Greenland ice sheet was much higher than now and its enormous weight caused the crust in that area of the world is slowly sinking into the mantle rock, which relented later. When much of the ice melted at the end of that time, the weight of the ice sheet was reduced and the bark began to recover, which still continues.
Bevis indicates that the existence of mantle flow beneath Greenland is not a surprise in itself. When the Grace mission (Experiment Climate and Gravity Recovery), a joint NASA and the German Space Agency, began measuring signals the seriousness worldwide in 2002, scientists knew they would have to separate the mass flow below the earth’s crust from changes in the ice sheet that covers it.
“Grace and measures the mass point. You can not tell the difference between the mass of ice and rock mass. Therefore, infer the variation of the ice mass from total mass change requires a model of all mass flows within the earth. If that model is wrong, what is the change in the ice mass inferred by Grace, “Bevis said.
For scientists, this variation of 7.6 percent in the total loss of ice in Greenland is overshadowed by the fact that before which parts of the ice sheet are being most affected by climate change was not known. The new results show that the pattern of ice loss is similar to that which has prevailed since the end of the last ice age.
“This result is a detail, but it is an important detail,” continued Bevis, who concluded: “By refining the spatial pattern of mass loss in the second layer of the world’s largest and most unstable ice, and learn how that model has evolved, we are constantly increasing our understanding of the processes of ice loss, which will lead to better informed projections of sea level rise. “
