According to geologist Billy Hay from the University of Colorado, the old estimate in 2007 on projected sea level rise given by the Intergovernmental Panel on Climate Change (IPCC) could be way off due to several key factors that their models were missing.
The IPCC’s most recent model suggested that by 2100, sea levels could rise between 0.2 and 0.5 meters. However, data on current sea levels indicate that sea level rise is on a much faster pace than a mere half meter in the next 100 years. While it seems improbable that the IPCC could be so off just five years after their last prediction, Hay believes that several natural feedback systems were neglected by the IPCC models and have skewed the projections.
At the meeting of The Geological Society of America in Charlotte, NC last week, Hay presented his theories on these feedbacks.
His first idea focused on Arctic sea ice. Since sea ice is already in the ocean, its melting does not directly raise sea levels. However, when the ice melts it creates a warming effect on the entire Arctic Ocean. As this fresh Arctic sea ice water melts, it gets pushed out and replaced by saltier waters from the south. With more open water, more heat is trapped which warms the entire Arctic. As a result, as ice from the Arctic sea ice melts, it indirectly leads to melting of ice in Greenland and northern Canada.
Sticking with Greenland, Hay then turned his attention to the enormous ice caps covering 80 percent of Greenland’s surface along with the ice caps of Antarctica. With a better understanding of water underneath these ice caps, Hay believes that their presence allows ice to literally slide off the land and into the ocean.
Recent data has backed up Hay’s belief: this past summer Greenland underwent its largest melt in modern history with 97 percent of its ice sheet melting between July 8 and July 12.
What worries Hay is the impact humans can have on speeding up the process of sea level increase. Hay noted that during the last interglacial period, sea levels rose 10 meters naturally.
The final feedback mechanism, which Hays believes is leading to faster rises in sea levels, is the groundwater being mined to fight drought across the globe. This once hidden source of water is being pumped to the surface and ultimately ending up in the ocean.
With his model adjustments, where does Hay think the seal levels could go to by 2100? It is possible that the oceans could spike a meter or more — a much higher estimate than that from the IPCC in 2007.
If sea levels do continue their dramatic rise, human populations could be impacted in a dangerous way. About ten percent of the world’s population and some of the world’s poorest regions are found in coastal regions in danger of flooding. Based on Hay’s projections it is possible that these regions will suffer from more flooding in the coming years, causing economic and personal damage. In the long term, coastal homes will be steadily pushed inland.