The melting of glaciers rises 0.7 centimeters per year sea level - CNN

Madrid. (EP). – A new studio of glaciers around the world through observations from two NASA satellites, has helped resolve differences in estimates of how glaciers are disappearing quickly and contribute to the elevation of level sea .

New research

glaciers of ice outside Greenland and Antarctica, repositories of 1 percent of all the ice on Earth, indicates they lost an average of 259 million tons of mass each year during the study period of six years, so the oceans increased 7 millimeters per year.

This amounts to about 30 percent of the total observed global rise in sea level over the same period and matches the combined contribution of sea level rise from ice in Greenland and Antarctica.

The study compares traditional ground-based measurements with satellite data from ICESat and GRACE missions of NASA, to estimate the loss of ice from glaciers in every region of the planet.

The study period runs from 2003-2009, the years in which the two missions overlap. “For the first time, we were able to very accurately restrict the amount by which these glaciers as a whole are contributing to sea level rise,” said Alex Gardner, Earth scientist at Clark University in Worcester, Massachusetts, and author of the study.

“These smaller ice bodies are losing as much mass as ice”. The study was published in the journal Science . ICESat, which ceased operations in 2009, measures the change of glaciers through laser altimetry bouncing laser pulses on the surface of the ice to report changes in the height of the ice sheet. ICESat’s successor, ICESat-2, is scheduled for release in 2016.

GRACE, still in operation, detects variations in the gravity field of the Earth as a result of changes in the distribution of the planet’s mass, including ice movement.

The new research found that all regions with glaciers lost mass from 2003-2009, with the greatest losses of ice in the Canadian Arctic, Alaska, the coast of Greenland, the southern Andes and the Himalayas. By contrast, peripheral glaciers of Antarctica, small ice bodies that are not connected to the main ice sheet contributed little to sea level rise during that period.

The study, which is also based on another of 2012 using only data from GRACE, found that ice loss from glaciers was lower than estimates derived from ground-based measurements. Current estimates predict that all glaciers in the world contain enough water to raise sea level by up to about 60 inches.

In comparison, the entire Greenland ice sheet has the potential to contribute about 6 meters to sea level rise and Antarctic ice about 60 meters. “Because the overall mass of glacial ice is relatively small compared to the huge ice sheets covering Greenland and Antarctica, people tend not to worry about it,” said study co-author, Tad Pfeffer, a glaciologist University of Colorado at Boulder.

“But it’s like a small bucket with a huge hole in the bottom: it may not be a very long, only a century or two, but as long as there’s ice on these glaciers, is a major contributor to the increased level sea. ” To make ground-based estimates of glacier mass changes, glaciologists situ measurements made along a line from the top of a glacier at its edge.

Scientists extrapolate these measurements to the entire surface of glaciers and held for several years to estimate the variation of the total mass of the glacier over time. While this type of measure is good for individual glaciers, tends to overestimate ice loss when the results are extrapolated to larger regions as the whole mountain ranges.

“ground observations can often only be collected at the most accessible glaciers, where is that thinning occurs more rapidly than regional averages,” said Gardner. “This means that when these measurements are used to estimate the variation of the mass of the entire region, it is determined that regional losses are too great.”

GRACE

not have sufficient resolution and ICESat has insufficient sampling density to study small glaciers, but estimates of mass change for larger regions are coincident in both satellites. “Without having these independent observations, there was no way of knowing that terrestrial observations were biased,” said Gardner. The research involved 16 researchers from 10 countries.