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CORVALLIS, Ore. - The Intergovernmental Panel on Climate Change, a United Nations-sponsored group of scientists, issued its latest report on the state of scientific understanding on climate change. Two Oregon State University faculty members played key roles in the landmark report.

Peter Clark, a professor in OSU's College of Earth, Ocean, and Atmospheric Sciences, was one of two coordinating lead authors on a chapter outlining sea level change. He and fellow coordinating lead author John Church of Australia oversaw the efforts of 12 lead authors and several dozen contributing scientists on the science of sea level change.

Philip Mote, director of the Oregon Climate Change Research Institute at OSU, was one of 12 lead authors on a chapter looking at the cryosphere, which is comprised of snow, river and lake ice, sea ice, glaciers, ice sheets, and frozen ground. The cryosphere plays a key role in the physical, biological and social environment on much of the Earth's surface.

"Since the last IPCC report, there has been increased scientific understanding of the physical processes leading to sea level change, and that has helped improve our understanding of what will happen in the future," Clark said.

"One of the things our group concluded with virtual certainty is that the rate of global mean sea level rise has accelerated over the past two centuries - primarily through the thermal expansion of the oceans and melting of glaciers," Clark added. "Sea level rise will continue to accelerate through the 21st century, and global sea levels could rise by 0.5 meters to at least one meter by the year 2100."

The rate of that rise will depend on future greenhouse gas emissions.

Among other findings, the sea level chapter also concluded that it is virtually certain that global mean sea level will continue to rise beyond the year 2100, and that substantially higher sea level rise could take place with the collapse of the Antarctic ice sheet.

Mote, who also is a professor in the College of Earth, Ocean, and Atmospheric Sciences, said analyzing the cryosphere is complex and nuanced, though overall the amount of snow and ice on Earth is declining.

The report notes: "Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent." Other cryosphere changes include:

• Greenland and Antarctica are not only losing ice, but the rate of decline is accelerating;
• The amount of sea ice in September has reached new lows;
• The June snow cover also has reached new lows and has decreased by an average of 11.7 percent per decade - or 53 percent overall - from 1967 to 2012;
• The reduction in snow cover can formally be attributed to human influence - work done by Mote and David Rupp of OSU.

 Rick Spinrad, OSU's vice president for research, praised the efforts of the two OSU faculty members for their contributions to the report.

 "OSU is a global leader in environmental research as reflected by the leadership roles of Dr. Clark and Dr. Mote in this seminal assessment," Spinrad said. "The impact of the IPCC report will be felt by scientists and policy makers for many years to come."

The IPCC report is comprised of 14 chapters, supported by a mass of supplementary material. A total of 209 lead authors and 50 review editors from 39 countries helped lead the effort, and an additional 600 contributing authors from 32 countries participated in the report. Authors responded to more than 54,000 review comments.

The report is available online at the IPCC site: http://www.ipcc.ch/