Himalayan glaciers will shrink by almost 10 percent, even if temperatures hold steady

Science Daily: Come rain or shine, or even snow, some glaciers of the Himalayas will continue shrinking for many years to come.

The forecast by Brigham Young University geology professor Summer Rupper comes after her research on Bhutan, a region in the bull's-eye of the monsoonal Himalayas. Published in Geophysical Research Letters, Rupper's most conservative findings indicate that even if climate remained steady, almost 10 percent of Bhutan's glaciers would vanish within the next few decades. What's more, the amount of melt water coming off these glaciers could drop by 30 percent.

Rupper says increasing temperatures are just one culprit behind glacier retreat. A number of climate factors such as wind, humidity, precipitation and evaporation can affect how glaciers behave. With some Bhutanese glaciers as long as 13 miles, an imbalance in any of these areas can take them decades to completely respond. "These particular glaciers have seen so much warming in the past few decades that they're currently playing lots of catch up," Rupper explains.

In fact, snowfall rates in Bhutan would need to almost double to avoid glacier retreat, but it's not a likely scenario because warmer temperatures lead to rainfall instead of snow. If glaciers continue to lose more water than they gain, the combination of more rain and more glacial melt will increase the probability of flooding -- which can be devastating to neighboring villages.

"Much of the world's population is just downstream of the Himalayas," Rupper points out. "A lot of culture and history could be lost, not just for Bhutan but for neighboring nations facing the same risks."...

The glacial lakes of Bhutan, NASA image

Melting glaciers raise sea level

Terra Daily via SPX: Anthropogenic climate change leads to melting glaciers and rising sea level. Between 1902 and 2009, melting glaciers contributed 11 cm to sea level rise. They were therefore the most important cause of sea level rise. This is the result of a new assessment by scientists of the University of Innsbruck. They numerically modeled the changes of each of the world's 300 000 glaciers.

Until 2100, glaciers could lead to an additional 22 cm of sea level rise. Since 1900 the global sea level has risen by approximately 20 cm. Melting glaciers are one of the causes - along with warming and thereby expanding sea water, melting Greenland and Antarctic ice sheets, and changing terrestrial water storage in dammed lakes and groundwater reservoirs.

A team of scientists at the University of Innsbruck has now assessed the contribution of melting glaciers to sea level rise during the 20th century. They numerically modeled each of the world's roughly 300 000 glaciers and used thousands of on-site measurements to validate the model results.

"These calculations show that between 1902 and 2009, glaciers contributed about 11 cm to sea level rise", says Dr. Ben Marzeion from the Institute for Meteorology and Geophysics. "This means they were the most important cause of sea level change."

Surprisingly, melt rates were more or less constant over time: While temperatures during the first decades of the 20th century were considerably lower, glaciers were larger and extended into lower and thus warmer areas. Additionally, brief but strong warm episodes in the Arctic led to strong glacier retreat in the Arctic in the 1930s and 1950s....

Fiescher Glacier, Valais, Alps of Switzerland, from Snapshots Of The Past, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license.

Glacial ghosts set sea-level trap for East Coast

Paul Voosen in E&E News: The United States has a debt, etched in stone, to pay back to the sea. Across the world, the oceans are rising. Because of human-caused warming, global sea level has increased at 3 millimeters a year for the past two decades. Sucking in 90 percent of the excess heat trapped by greenhouse gases, the ocean is the world's thermometer, running hot. It's the largest sign, and impact, of climate change.

But as the surge sloshed into New York Harbor last week by Superstorm Sandy made clear, sea-level rise is also a deeply local phenomenon. There is no average ocean. There are only particular coastlines, shaped by geology, currents and gravity. The past matters. And in few places does it matter more than the United States.

Most of the country's eastern coastline is caught at the end of an unstoppable collapse, stemming from the loss of ice sheets many millennia ago. It's a complex process, with one succinct outcome: The ice age set a sea-level trap for the United States. From Massachusetts to the Carolinas, the Eastern Seaboard is sinking.

"[It's] going to experience significantly more sea-level rise than the global average," said Jerry Mitrovica, a geophysicist at Harvard University and expert on the continent's glacial legacy. "The U.S. East Coast could be at double the global average."...

The Greenland Ice Sheet from the air, shot by Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license