Water from the world’s shrinking glaciers was responsible for almost a third of the rise in sea levels between 2003 and 2009, shows new research.
An international team of scientist compared data gleaned from two NASA satellites as well as traditional ground measurements from glaciers around the world.
Their work, published in the journal Science , is the most accurate estimation of how glaciers contribute to sea level rises to date.
“For the first time, we’ve been able to very precisely constrain how much these glaciers as a whole are contributing to sea rise,” says lead author Assistant Professor Alex Gardner, assistant geography professor at Clark University in Worcester, Massachusetts.
“These smaller ice bodies are currently losing about as much mass as the ice sheets.”
The most significant ice losses occurred in Arctic Canada, Alaska, coastal Greenland, the southern Andes and the Himalayas, the study found.
The glaciers outside of the Greenland and Antarctic sheets lost an average of roughly 260 billion metric tons of ice annually during the period, leading to a rise in ocean levels of about 0.7 millimeters per year.
By contrast the glaciers in Antarctica, smaller ice masses that are not connected to the ice sheet, made scarcely any contribution to sea-level rise over the study period.
If you are wandering around Greenland’s ice sheet and you run into this crazy thing, it is NASA’s GROVER (government acronym for something Goddard Remotely Operated Vehicle for Exploration and Research). It is solar powered and it crawls around Greenland on its own and uses ground-penetrating radar to look at ice. And it’s cool.
NASA robot explores ice in Greenland. Video. Will explore for months at a time via remote. Possibly prototype to explore other planets.
Trailer for Chasing Ice, an insane enviromentary that has swept-up dozens of awards. Scientists risk their lives over three-years to record the death of several of the world’s last remaining glaciers. Our glaciers are melting, disappearing faster than thought possible, and all due to a warming earth.
Sea ice is any form of ice found at sea that originated from the freezing of sea water. It is the most visible feature of the Arctic Ocean, with its extent waxing and waning with the seasons. Ice thickness is highly variable, ranging from a thin veneer to tens of meters. While the existence of sea ice reflects the cold conditions inherent to high latitudes, sea ice also strongly modulates the energy budget and climate of the Arctic and beyond, particularly because it is white, and hence reflects much of the sun’s energy back to space (it has a high albedo) and also through acting as a lid, insulating the underlying ocean from a generally much colder atmosphere.
Historically, at its maximum extent in March, Arctic sea ice covered an area more than 15 million square kilometers, somewhat less than twice the size of the contiguous United States. The minimum extent, occurring in September, the end of the melt season, was typically around 7.0 x106 km2. However, as assessed over the modern satellite record spanning 1979 to the present, Arctic sea ice extent exhibits downward linear trends for all months, weakest in winter and strongest for September. The downward September trend appears to have accelerated over the past decade. Through 2001, the September trend stood at -7.0% per decade. Through 2012, it was more than twice as large at -14.3% per decade. The six lowest September extents in the satellite record have all occurred in the past six years, with September of 2012 setting a new low mark. Decreased summer ice extent has been accompanied by large reductions in winter ice thicknesses that are primarily explained by changes in the ocean’s coverage of thick multiyear ice (MYI). MYI is ice that has survived at least one summer melt season. In the mid-1980s, MYI accounted for 70% of total winter ice extent, whereas by the end of 2012 it had dropped to less than 20%. At the same time the proportion of ice older than 5 years declined from 50% of the MYI pack to less than 8%.
Ice loss is also contributing to strong rises in Arctic air temperature during autumn and winter, not just at the surface, but extending through a considerable depth of the atmosphere. As discussed, sea ice acts as a lid, insulating the underlying ocean from a generally much colder atmosphere. With less ice, the insulating effect is weaker, so heat can readily be transferred from the ocean to the atmosphere above. This strong warming, termed Arctic amplification, is starting to extend beyond areas of ice loss to influence Arctic land areas.
Continued loss of the ice cover is in turn likely to impact on patterns of atmospheric circulation and precipitation not just within the Arctic, but into middle latitudes; there is evidence that this is already occurring. The basic reason for this is that the outsized warming of the Arctic changes the atmospheric stability and temperature differences between the Arctic and lower latitudes. Finally, as the ice cover retreats, the Arctic is becoming more accessible for marine shipping as well as oil and natural gas exploration, increasing the economic and strategic importance of the region.
Dr. Mark Brandon, a Polar Oceanographer (@icey_mark), discusses how humans impact the Arctic. It’s a high-level talk, meaning it’s easy to follow and not very sciencey. He makes much use of the fact that fire retardants are routinely found in the fat of polar bears and other animals to show how our pollution travels north.
A blog about the interactions between the built environment, people, and nature.
I'm a climate change consultant specializing in climate adaptation, environmental law, and urban planning based in the U.S. In addition to traveling and hiking, I research, publish, and lecture on how cities can adapt to climate change.
Professional and sponsorship inquiries, please