NEW BRUNSWICK/PISCATAWAY, N.J. – Rutgers' David Robinson is co-organizer of a symposium, "Deciphering the Complex Changes in Global Ice and Snow," to be held at 3 p.m., Saturday, Feb. 16 during the annual meeting of the AAAS (American Association for the Advancement of Science) in Boston.
Robinson, chair of Rutgers' department of geography and New Jersey state climatologist, is one of the leading scientists monitoring the extent of continental snow cover. He will open the symposium with his paper, "The Northern Hemisphere's Spring Snow Drought," which draws attention to convincing evidence of global climate change.
AAAS, the world's largest general science organization and publisher of the peer-reviewed journal Science, describes its meeting as "the world's finest showcase for the excitement and significance of scientific discovery." Sessions are scheduled February 14-19 at the Sheraton Boston Hotel, Hynes Convention Center and Boston Marriott-Copley Place.
The symposium will bring together experts in various dimensions of climatology to assess the state of the earth's cryosphere – snow and ice in its various forms. "Much has been written piecemeal in recent years on the thinning of Arctic sea ice, calving of Antarctic ice sheets, changes in glaciers and shifting patterns in snow cover," Robinson said. "Bringing it all together in Boston allows us to present a bigger, stronger story about global climate change."
Robinson's presentation will focus on snow cover, which he describes as the largest surface variable in the climate system – a seasonal part of the cryosphere that comes and goes in most areas of the earth. In any given winter, Northern Hemisphere continents are covered by approximately 45 to 50 million square kilometers of snow. In summer, snow cover shrinks to a few million kilometers, most of which sits on top of the Greenland ice sheet.
Robinson's data comes from satellite monitoring of the Northern Hemisphere over the past three decades combined with earlier historic records gathered from surface stations. "Never before have we had such a comprehensive picture of the extent of snow cover over time," he reports.
This data shows that the amount of snow covering in North America and Eurasia has been shrinking over the years and melting earlier, suggesting an earlier and longer spring, Robinson said. "At the same time, other indicators such as temperature records are also suggesting an earlier spring."
The early loss of snow has contributed significantly to higher spring temperatures that dry and warm the ground and, in turn, warm the atmosphere. The trend over time closely parallels some computer model projections of greenhouse-enhanced warming.
"I cannot conclude that this early spring loss of snow cover is absolutely, positively linked with human, greenhouse-induced warming," Robinson says. "However, I do think it is another piece of evidence that, along with records of temperature and other environmental indicators, leaves one rather convinced that humans are having some influence on the global climate right now."
The symposium will also focus on sea ice as another significant seasonal variable. In the Southern Hemisphere, sea ice covers about 20 million square kilometers in winter and drops to four to five million in summer. "Both snow cover and sea ice are major variables that have implications for the earth's energy balance and, in turn, our climate system," observes Robinson.
Robinson and his colleagues will also discuss the condition of alpine glaciers in mountainous areas of the middle and high latitudes and even down in the tropics. "Ice is even being lost from the top of Tanzania's Mount Kilimanjaro, and some projections show that it might be totally gone within the next decade or two," he cautions. "These high-altitude glaciers may be a kind of canary, providing an early warning in the whole global-change scenario."
The symposium will also discuss the ice caps that sit atop Greenland and the South Pole. Big pieces of these ice sheets – some the size of Rhode Island or Delaware – are breaking off and moving into polar oceans. Climatic change could increase the flow of these massive fragments, potentially raising global sea levels.
"With the snow cover, ice caps and glaciers that make up the global cryosphere in an apparent state of decline, the gathering of experts in these areas for this symposium is both timely and relevant," said Robinson.