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Ocean Research


April 2011 Issue

68 Percent of New England and Mid-Atlantic Beaches Eroding
An assessment of coastal change over the past 150 years has found that 68 percent of beaches in the New England and Mid-Atlantic region are eroding, according to a new U.S. Geological Survey (USGS) report.

Scientists studied more than 650 miles of the New England and Mid-Atlantic coasts and found the average rate of coastal change—taking into account beaches that are both eroding and prograding—was negative 1.6 feet per year. Of those beaches eroding, the most extreme case exceeded 60 feet per year.

The past 25 to 30 years saw a small reduction in the percentage of beaches eroding, dropping to 60 percent, possibly as a result of beach restoration activities, USGS said.

The Mid-Atlantic coast—from Long Island, New York, to the Virginia-North Carolina border—is eroding at higher average rates than the New England coast, the study found. The difference in the type of coastline, with sandy areas being more vulnerable to erosion than areas with a greater concentration of rocky coasts, was the primary factor.

The researchers found that although coastal change is highly variable, the majority of the coast is eroding throughout both regions, indicating erosion hazards are widespread. For more information, visit www.usgs.gov.

Ice Sheet Melt Accelerating, 20-Year Study Finds
The Greenland and Antarctic ice sheets are losing mass at an accelerating pace, according to a new study. The findings of the study—the longest to date of changes in polar ice sheet mass—suggest these ice sheets are overtaking ice loss from mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.

The results of the study was published in March in Geophysical Research Letters.

The nearly 20-year study reveals that in 2006, a year in which comparable results for mass loss in mountain glaciers and ice caps are available from a separate study conducted using other methods, the Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average.

The pace at which the polar ice sheets are losing mass was found to be accelerating rapidly. Each year over the course of the study, the two ice sheets lost a combined average of 36.3 gigatonnes more than they did the year before. In comparison, the 2006 study of mountain glaciers and ice caps estimated their loss at 402 gigatonnes a year on average, with a year-over-year acceleration rate three times smaller than that of the ice sheets.

"That ice sheets will dominate future sea level rise is not surprising—they hold a lot more ice mass than mountain glaciers," said lead author Eric Rignot, of NASA's Jet Propulsion Laboratory and the University of California, Irvine. "What is surprising is this increased contribution by the ice sheets is already happening. If present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations Intergovern?mental Panel on Climate Change in 2007."

The authors conclude that if current ice sheet melting rates continue for the next four decades, their cumulative loss could raise sea level by 15 centimeters by 2050. When this is added to the predicted sea level contribution of eight centimeters from glacial ice caps and nine centimeters from ocean thermal expansion, total sea level rise could reach 32 centimeters.

The authors caution that considerable uncertainties remain in estimating future ice loss acceleration. For more information, visit www.agu.org/journals/gl.

Shallow Crustal Faults Pose Risk, New Zealand Earthquake Shows
The destructive and deadly earthquake that hit Christchurch, New Zealand in February was only a moderate 6.3 magnitude, but it had certain characteristics that offer an important lesson to cities up and down the West Coast of North America facing similar risks, experts say.

This earthquake was an aftershock of the much more powerful 7.1-magnitude earthquake that struck New Zealand last September near the same area and caused no deaths.

This year's weaker earthquake was much shallower, was situated directly under Christchurch, hit during the lunch hour when more people were exposed to damage, and shook sediments that were prone to "liquefaction," which can magnify the damage done by the ground shaking.

That same description fits many major cities and towns in Washington, Oregon, California and British Columbia, said Robert Yeats, a researcher on New Zealand and U.S. seismic risks and professor emeritus of geology at Oregon State University.

The risks from comparatively shallow "crustal" faults, Yeats said, are often given less attention compared to the concerns about the major subduction zone earthquake facing the Pacific Northwest in its future, or other major quakes on famous plate boundaries such as the San Andreas Fault. There are dozens or hundreds of faults such as this that can cause serious earthquakes in the West, Yeats said.

For more information, visit www.oregonstate.edu.

International Consortium to Explore Iron and the Oceans
A group of 12 universities and research centers from around the world, called ISIS, has formed to explore the potential impact of iron fertilization of the oceans to reduce the amount of carbon dioxide (CO2) in the Earth's atmosphere.

Iron fertilization in the oceans has been researched for its effectiveness in stimulating plankton growth to sequester carbon. Plankton use CO2 from the ocean surface in photosynthesis to produce organic carbon, a small fraction of which sinks. This process eventually can carry carbon to the depths of the ocean and keep it there for decades to centuries.

Some opponents to the approach cite environmental concerns from "geoengineering" the ocean, but ISIS isn't ready to geoengineer, said Woods Hole Oceanographic Institution Senior Scientist Ken Buesseler, who helped organize ISIS.

"Without good science, governments or corporations might move ahead with geoengineering projects prematurely, particularly as carbon markets develop or climate change threats become more serious," he said. "We need to be working now, to ensure that we know potential impacts and consequences."

For more information, visit www.whoi.edu.


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