Zachariae Isstrom Glacier in Accelerated Retreat

Greenland’s ZI losing 5 billion tons of mass per year: Report

The northeast Greenland glacier Zachariae Isstrom  (ZI) has come unmoored from a stabilizing sill and is crumbling into the North Atlantic Ocean at an accelerated rate of 5 billion tons per year, according to a report published in the current issue of Science.

ZI, which holds “a 0.5-meter sea-level rise equivalent,” entered a phase of accelerated retreat in fall 2012, says the report.

“The acceleration rate of its ice velocity tripled, melting of its residual ice shelf and thinning of its grounded portion doubled, and calving is now occurring at its grounding line. Warmer air and ocean temperatures have caused the glacier to detach from a stabilizing sill and retreat rapidly along a downward-sloping, marine-based bed. ”

“Zachariae Isstrom is being hit from above and below,” said senior author Eric Rignot, a researcher at Earth system science at UCI. “The top of the glacier is melting away as a result of decades of steadily increasing air temperatures, while its underside is compromised by currents carrying warmer ocean water, and the glacier is now breaking away into bits and pieces and retreating into deeper ground.”

Its “equal-ice-volume” neighbor Nioghalvfjerdsfjorden, which is also melting rapidly, though retreating at a slower rate along an upward-sloping bed, drain a sector about 200,000 km² in size, or 12% of the Greenland Ice Sheet, says the report

“These two glaciers together drain the northeast Greenland ice stream, the only large, dynamic feature that extends continuously deep to the ice sheet interior near Greenland’s summit. This marine-based sector holds a 1.1-m sea-level rise equivalent.”

“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers were to start retreating,” says Rignot. “We no longer need to wonder; for a couple of decades now, we’ve been able to directly observe the results of climate warming on polar glaciers. The changes are staggering and are now affecting the four corners of Greenland.”

The report is published in the current issue of Science, posted at http://www.sciencemag.org/  [Science. ISSN 0036-8075 (print), 1095-9203 (online) ]

China’s Glaciers Shrink by 18 Percent

Glaciers in China retreat by 18 pct in 5 decades

China’s glaciers have retreated by about 18 percent since the 1950s, say Chinese scientists, reported Xinhua.

Using data gathered by remote sensing between 2006 and 2010, the scientist calculated 48,571 glaciers covering 51,840km² in the western China, the report quoted the Chinese Academy of Sciences (CAS) as saying. CAS released its second catalog of the country’s glaciers on Saturday.

“An average of 243.7 square km of glacial ice had disappeared every year over the past half century, according to the survey by the CAS Cold and Arid Regions Research Institute.

“The worst shrink was detected on the Altai Mountains located in Xinjiang Uygur Autonomous Region and the Gangdise Mountain in the Tibet Autonomous Region, with retreat hitting 37.2 percent and 32.7 percent respectively over the past five decades,” said the report.

“Major glaciers on the Qinghai-Tibet plateau, especially the east part of Gangdise as well as the southern and western Himalayas were melting at the most rapid pace, with areas shrinking by 2.2 percent every year, according to the survey.”

Unfortunately, the report didn’t include the decadal rate of retreat for comparison purposes.

Original Caption: Photo taken on Dec. 19, 2011 shows the shrinking Puruo Gangri glacier, southwest China’s Tibet Autonomous Region. According to the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences (CAS), glaciers on the Qinghai-Tibet Plateau and surrounding areas have shrunk by 15 percent from 53,000 to 45,000 square kilometers over the past three decades. (Xinhua/Chogo). More images…

However, in May 2014, “a state laboratory director with the Cold and Arid Regions Environmental and Engineering Research Institute of CAS,” was reported as saying that glaciers in the Tibetan Plateau had been shrinking since the 20th century, and that the rate of retreat had accelerated since the 1990s.

“More and bigger cracks have appeared in ice at regions of an altitude above 6,300 meters in Mount Qomolangma, a sign of rapidly melting glaciers,” Xinhua reported him as saying.

“Southwest China’s Qinghai-Tibet Plateau, the major source of the country’s largest rivers, has seen its glaciers shrink rapidly over the past 30 years,” Xinhua reported CAS as saying in May 2014.

CAS stated that glaciers on the plateau and surrounding areas had shrunk by 15 percent from 53,000 to 45,000km² over the past three decades.