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Recent NASA photos showed the opening of the
Northwest Passage and revealed that a third of the Arctic’s sea ice
has melted in recent years. Are sea levels already starting to rise
accordingly — and, if so, what are the effects?
Researchers were astounded when, in the fall of 2007,
they discovered that the year-round ice pack in the Arctic Ocean had lost
some 20 percent of its mass in just two years, setting a new record low
since documentation of the terrain with satellite imagery was begun in
1978. Without action to stave off climate change, some scientists believe,
at that rate all of the year-round ice in the Arctic could be gone by as
early as 2030. This massive reduction has allowed an ice-free
shipping lane to open through the fabled Northwest Passage along northern
Canada, Alaska, and Greenland. Although the shipping industry — which
now has easy northern access between the Atlantic and Pacific oceans
— may be cheering this “natural” development, scientists
worry about the impact of the resulting rise in sea levels around the
world. With about a third of the world’s population
— and 25 percent of Americans — living within 300 feet of an
ocean coastline, sea-level rise is a big deal. According to the
Intergovernmental Panel on Climate Change, made up of leading climate
scientists, sea levels have risen some 3.1 millimeters per year since 1993.
The World Wildlife Fund reports that low-lying island
nations, especially in equatorial regions, have been hardest hit by this
phenomenon, and some are threatened with total disappearance. Rising seas
have already swallowed up two uninhabited islands in the Central Pacific.
On Samoa, thousands of residents have moved to higher ground as shorelines
have retreated by as much as 160 feet, and islanders on Tuvalu are
scrambling to find new homes as saltwater intrusion has made their
groundwater undrinkable and increasingly strong hurricanes and ocean swells
have devastated shoreline structures. WWF says that rising seas throughout tropical and
subtropical regions of the world have inundated coastal ecosystems,
decimating local plant and wildlife populations. In Bangladesh and
Thailand, coastal mangrove forests — important buffers against storms
and tidal waves — are giving way to ocean water. Unfortunately, even if we curb global-warming
emissions today, these problems are likely to get worse before they get
better. According to marine geophysicist Robin Bell of Columbia
University’s Earth Institute, sea levels rise by about 1/16 inch for
every 150 cubic miles of ice that melts off one of the poles. “That may not sound like a lot, but consider
the volume of ice now locked up in the planet’s three greatest ice
sheets,” she writes in a recent issue of Scientific American. “If the
West Antarctic ice sheet were to disappear, sea level would rise almost 19
feet; the ice in the Greenland ice sheet could add 24 feet to that; and the
East Antarctic ice sheet could add yet another 170 feet to the level of the
world’s oceans: more than 213 feet in all.” Bell underscores
the severity of the situation by pointing out that the 150-foot tall Statue
of Liberty could be completely submerged within a matter of decades.
For more information:
Intergovernmental Panel on Climate Change, www.ipcc.ch; WWF, www.panda.org;
Earth Institute at Columbia University, www.earth.columbia.edu.
Send questions to Earth Talk, care of E/The Environmental Magazine,
P.O. Box 5098, Westport, CT 06881 or e-mail earthtalk@emagazine.com.
This article appears in Jul 3-9, 2008.
