It might take stunts like an underwater cabinet meeting conducted by the president of the Maldives to illustrate the potential consequences of rapidly increasing sea levels, according to glaciologist Robert Bindschadler of NASA's Goddard Space Flight Center. In a lecture on Friday at the Thayer School of Engineering, "Waking Giants: Ice Sheets in a Warming World," Bindschadler argued that the public must realize that some parts of the world will eventually be entirely submerged by melting glaciers, reporting that ice sheets are becoming more active and will likely increase the sea level by one meter within the next century.
Outlet glaciers extended sheets of moving ice like the Jakobshavn Glacier in Greenland have begun to accelerate in recent years, resulting in huge ice streams that move cubic kilometers of ice per year and leave behind building-sized icebergs, Bindschadler said.
"Previously, the Jakobshavn Glacier was moving 10 kilometers every 50 years," Bindschadler said. "In late 1999, it started to retreat much faster, moving the next ten kilometers in five years rather than 50. This drains at least 10 percent of the Greenland ice sheet and creates a very dynamic environment."
By using satellites to monitor the levels of snowfall accumulation and the amount of melting ice, glaciologists are able to determine if a glacier is gaining or losing mass, according to Bindschadler.
"Ice sheets are losing mass," Bindschadler said. "Antarctica a few decades ago was in mass balance; recently, it's been losing mass faster and faster."
Ice shelves, which take thousands of years to form, can sometimes break up and disintegrate within days, according to radar data collected by glaciologists, Bindschadler said.
As temperatures in Greenland and Antarctica rise, the accumulation of ice through snowfall is predicted to increase by approximately 10 percent, because the atmosphere will be capable of holding more moisture, he said. However, glaciologists also project that melting will increase by 50 percent and ice flow will increase by an even greater amount.
"Water is the agent of change killing the ice sheets," Bindschadler said. "Water is hot if you're an ice sheet not in a good way."
Water has the ability to destroy glacial structure, Bindschadler said. As it fills cracks in glaciers, it breaks the ice into tall, thin blocks and accelerates glacial movements that increase sea level.
Glaciologists hypothesize that water flows through the ice until it is blocked by an impermeable sheet beneath the glacier. As it runs across the sheet, it lubricates the glacier and increases ice flow speed by up to 70 percent, Bindschadler said.
Because models of ice sheet movement are not precise, scientists can only estimate changes in sea level using a combination of historical correlations and current data, according to Bindschadler.
All methods of calculation suggest that sea levels will rise by approximately one meter by 2100, intensifying the effects of oceanic natural disasters and displacing millions of people, Bindschadler said. Over 100 million people in Asia live within one meter of sea level and the economic impact would be the equivalent of a $944-billion loss of gross domestic product globally, he said.
"A lot of people live in the areas that will be new ocean," Bindschadler said. "It is a disturbing story. This is our future; it's not a liberal conspiracy."
