Tutorial: Warming Air, Rising Seas

October 13th, 2011 | 1 Comment
Climate Change, Okeanos Tutorials, The View From Lazy Point

Adapted from: 2011. The View From Lazy Point. Henry Holt Co.  New York.

Twenty thousand years ago when the Ice Age froze an enormous quantity of Earth’s water, sea level was nearly 400 feet (about 120 m) lower than today. Vast areas that are now seafloor were plains grazed by herds of animals. But the rise has been slow—literally a glacial pace. But now “glacial pace” is faster than it used to be, since nearly all the world’s glaciers— about 90 percent—are melting, faster.

And because seawater expands as it warms, warming ocean water compounds ocean rise caused by melting ice.

During all of human civilization, neither sea level nor the rate of its rise has ever been higher, or faster, than now. Sea level has risen about 8 inches (20 cm) over the last 100 years. And the rate of rise is accelerating.

“There has been nothing like this rate of sea level rise in the last 1,000 years,” says climatologist Stefan Rahmstorf, professor of oceanography at the University of Potsdam, Germany. “If there had been, Roman-built wharves would be four meters (13 feet) underwater—and they’re not.”

Sea ice can melt all it wants to; that won’t raise sea levels. It’s already in the ocean, displacing all the water its mass will ever displace. That’s why a drink with ice in it doesn’t overflow when the ice melts. Melting land ice—raises the sea. There’s still enough land-ice worldwide to raise sea level another 240 feet (73 m).

The Greenland Ice Sheet is up to two miles (3 km) thick and a little smaller than Mexico. Melted, it would raise global sea level by over 20 feet (6 m). That would take centuries. But since 2000, some of Greenland’s major glaciers—each draining enormous areas and already among the fastest-moving glaciers on Earth—have doubled their speed. Overall, Greenland’s rate of ice loss tripled between 2001 and 2006, to about 50 cubic miles (200 cubic kilometers) a year. (The city of Los Angeles uses about one cubic kilometer of water per year.) It continues to accelerate.

Professor Rahmstorf says, “The current change is extremely fast compared to past global change.”

“The acceleration of the melting isn’t factored into most models designed to predict sea level rise,” adds Julian Dowdeswell, who directs the Scott Polar Research Institute at the University of Cambridge in Great Britain. “Our minimum prediction for sea level is a half-meter (about 1.5 feet) rise over the next 100 years,” Julian says, “but many glaciologists think it will rise much higher than currently predicted in this century, at least a meter (3 feet), maybe even a meter and a half (5 feet).”

The slow tsunami of rising sea will inexorably sweep millions to higher ground. The World Bank says that as sea-level rises three feet or 1 m (likely early in the next century, possibly even in this century), in Bangladesh alone 30 million people will have to squeeze inland, while half of Bangladesh’s rice fields would be spoiled by saltwater. Already among the world’s first climate refugees: 500,000 former inhabitants of Bhola Island in Bangladesh, left homeless after half of the island became permanently inundated in 2005.

The National Defense University, an educational institute overseen by the U. S. military in Washington, D.C., explored the potential impact of a hypothetical flood in Bangladesh that sent hundreds of thousands of refugees streaming into neighboring India. In real life, India is already racing to build a 2,100-mile (3,400 km) fence. “It gets real complicated real quickly,” said Deputy Assistant Secretary of Defense Amanda J. Dory, while helping the Pentagon try to incorporate climate change into national security planning.

The main cause of the warming temperatures that are causing the rise in sea level, remember, is the carbon dioxide that’s released when we burn fossil fuels. Lord Nicholas Stern, former chief economist and senior vice-president of the World Bank, warned that failing to reduce carbon dioxide and other world-warming gas emissions could bring “an extended world war.”

Australia’s Defense Ministry warns that while Australia should ease suffering caused by global warming, if conflict erupts the country should use its military “to deal with any threats.” It won’t be pretty.

Many cities were situated to take advantage of—so they now depend on—meltwater from glaciers and snowpack. Water as lifeblood. As South America’s glaciers and snowpack shrivel, La Paz, Bogotá, Santiago—to where might these cities move? The summer weep of Himalayan glaciers feeds river water to 1.3 billion people, including 40 percent of the people from India to south China. Seventy percent of the Ganges River’s water comes from the Gangotri Glacier, which will likely disappear in a few decades, making the sacred Ganges an intermittent, seasonal river for the nearly half-billion people dependent on it. Glaciers that feed both China’s Yellow River (whose basin is home to 150 million people) and the Yangtze River (whose 370 million people rely heavily on river-irrigated rice) are shrinking at seven percent annually. Glaciers also feed the Indus, Brahamaputra, and Mekong Rivers. Chinese spokespeople often downplay environmental problems. On the issue of glaciers and rivers, Chinese Academy of Sciences representative Yao Tandong had this assessment: “The full-scale glacier shrinkage in the plateau regions will eventually lead to an ecological catastrophe.”

And the ensuing unrest will likely rise and widen, like the sea itself. It will cost us time and treasure—and probably blood.

So ask not for whom the bell tolls. Those warning gongs are for everyone. Refugees displaced by environmental problems (drought, deforestation, sea level rise—) now equal the number displaced by things like political oppression, religious persecution and ethnic troubles—about 25 million a year. Predicted droughts and coastal flooding from rising sea level would displace around 200 million. If climate changes really do create hundreds of millions of refugees, how will people avoid widening havoc?

Life will go on; it’s not the end of the world. But we’re running high-stakes risks because we’re fundamentally messing with the stability that’s prevailed during everything we call civilization.

References and Further Reading:

Greenland ice melting: Dowdeswell, J. A., 2006, “The Greenland Ice Sheet And Global Sea-Level Rise,” Science 311:963 964.

Greenland melting rate change, and Los Angeles uses one cubic kilometer of water: Rincon, P., 2006, “Greenland Ice Swells Ocean Rise,” BBC news, Feb. 16, online.

Between 2001 and 2006 Greenland’s ice sheet tripled its rate of loss: Reach, J., 2006 “Greenland Ice Sheet Is Melting Faster, Study Says,” National Geographic News, August 10, online. Also: Howat, I. M., 2007, “Rapid Changes In Ice Discharge From Greenland Outlet Glaciers,” Scienceexpress.org, 8 February, available online.

Climate refugees: Friedman, L., 2009, “How Will Climate Refugees Impact National Security?” Scientific American, March 23.

Sinking Indonesian islands: “Mass Relocation Planned As Seas Rise,” Financial Times, November 1, 2008, available online.

Well over half a million: Barnett, J and Adger,W. N., 2003, “Climate Dangers And Atoll Countries,” Climatic Change 61: 321–37.

Something approaching a hundred million: Brooks, N., et al., 2006, Sea Level Rise: Coastal Impacts And Responses, German Advisory Council on Climate Change, Berlin, available online.

Cities exposed to the sea: German Advisory Council on Global Change, 2006, The Future Ocean–Warming Up, Rising High, Turning Sour, German Advisory Council on Global Change, Berlin, available online.

Thirty million in Bangladesh: Chopra, A., 2009, “Salt Surge Puts Crops In Peril,” The National, available online.

At risk from rising sea-level: Myers, N., 2002, “Environmental Refugees: A Growing Phenomenon Of The 21st Century,” Philosophical Transactions of the Royal Society B 357: 609–613.

“It gets real complicated:” Broder, J.M., 2009, “Climate Change Seen As Threat To U.S. Security,” New York Times, August 9.

India is building a fence: Friedman, L., 2009, “How Will Climate Refugees Impact National Security?” Scientific American, March.


One Response to “Tutorial: Warming Air, Rising Seas”

  1. Anne says:

    Hello and thank you for an excellent website. So-called environmentally induced migration is multi-level problem. According to Essam El-Hinnawi definition form 1985 environmental refugees as those people who have been forced to leave their traditional habitat, temporarily or permanently, because of a marked environmental disruption (natural or triggered by people) that jeopardised their existence and/or seriously affected the quality of their life. The fundamental distinction between `environmental migrants` and `environmental refugees` is a standpoint of contemporsry studies in EDPs.

    According to Bogumil Terminski it seems reasonable to distinguish the general category of environmental migrants from the more specific (subordinate to it) category of environmental refugees.

    Environmental migrants, therefore, are persons making a short-lived, cyclical, or longerterm change of residence, of a voluntary or forced character, due to specific environmental factors. Environmental refugees form a specific type of environmental migrant.

    Environmental refugees, therefore, are persons compelled to spontaneous, short-lived, cyclical, or longer-term changes of residence due to sudden or gradually worsening changes in environmental factors important to their living, which may be of either a short-term or an irreversible character.

Leave a Reply