The study finds that if Greenland ice melts at moderate to high rates, ocean circulation by 2100 may shift and cause sea levels off the northeast coast of North America to rise by about 30 to 50 centimeters (12 to 20 inches) more than other coastal areas. The research builds on recent reports that have found that sea level rise associated with global warming could adversely affect North America, and its findings suggest that the situation is even more urgent than previously believed.
"If the Greenland melt continues to accelerate, we could see significant impacts this century on the northeast U.S. coast from the resulting sea level rise," says Aixue Hu, a scientist with the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, and lead author of the paper. "Major northeastern cities are directly in the path of the greatest rise."
Hu's paper will be published on 29 May in Geophysical Research Letters, a journal of the American Geophysical Union (AGU). A previous study in Nature Geoscience in March warned that warmer water temperatures could shift ocean currents in a way that would raise sea levels off the Northeast by about 20 cm (8 in) more than the average global sea level rise. But it did not include the additional impact of Greenland ice, which at moderate to high melt rates would further accelerate changes in ocean circulation and drive an additional 10 to 30 cm (4 to 12 in) of water rise toward heavily populated areas in northeastern North America on top of average global sea level rise. More remote areas in extreme northeastern Canada and Greenland could see even higher sea level rise.
Scientists have been cautious about estimating average sea level rise this century in part because of complex processes within ice sheets. The 2007 assessment of the Intergovernmental Panel on Climate Change projected that sea levels worldwide could rise by an average of 18 to 58 cm (7 to 23 inches) this century, but many researchers believe the rise will be greater because of dynamic factors in ice sheets that appear to have accelerated the melting rate in recent years.
To assess the impact of Greenland ice melt on ocean circulation, Hu and his coauthors used the Community Climate System Model, an NCAR-based computer model that simulates global climate. They considered three scenarios: the melt rate continuing to increase by 7 percent per year, as has been the case in recent years, or the melt rate slowing down to an increase of either 1 or 3 percent per year.
If Greenland's melt rate slows down to a 3 percent annual increase, the study team's computer simulations indicate that the runoff from its ice sheet could alter ocean circulation in a way that would direct about 30 cm (one foot) of water rise toward the northeast coast of North America by 2100. This would be on top of the average global sea level rise expected as a result of global warming. Although the study team did not try to estimate that mean global sea level rise, their simulations indicated that melt from Greenland alone under the 3 percent scenario could raise sea levels by an average of 53 cm (21 inches).
If the annual increase in the melt rate dropped to 1 percent, the runoff would not raise northeastern sea levels by more than the 20 cm (8 in) found in the earlier study in Nature Geoscience. But if the melt rate continued at its present 7 percent increase per year through 2050 and then leveled off, the study suggests that the northeast coast could see as much as 51 cm (20 in) of sea level rise above a global average that could be several feet. However, Hu cautioned that other modeling studies have indicated that the 7 percent scenario is unlikely.
In addition to sea level rise, Hu and his co-authors found that, if the Greenland melt rate were to defy expectations and continue its 7 percent increase, this would drain enough fresh water into the North Atlantic to weaken the oceanic circulation that pumps warm water to the Arctic. Ironically, this weakening of the meridional overturning circulation would help the Arctic avoid some of the warmed ocean impacts of global warming and lead to at least the temporary recovery of Arctic sea ice by the end of the century.
The northeast coast of North America is especially vulnerable to the effects of Greenland ice melt because of the way a north-south oceanic flow, known as the meridional overturning circulation, acts like a conveyor belt transporting water through the Atlantic Ocean. The circulation carries warm Atlantic water from the tropics to the north, where it cools and descends to create a dense, deep layer of cold water flowing south. As a result, sea level is currently about 71 cm (28 in) lower in the North Atlantic than the North Pacific, which lacks such a dense layer.If the melting of the Greenland Ice Sheet were to increase by 3 percent or 7 percent yearly, the additional fresh water could partially disrupt the northward conveyor belt.
This would reduce the accumulation of deep, dense water. Instead, the deep water would be slightly warmer, expanding and elevating the surface across portions of the North Atlantic.
"The oceans will not rise uniformly as the world warms," says NCAR scientist Gerald Meehl, a co-author of the paper. "Ocean dynamics will push water in certain directions, so some locations will experience sea level rise that is larger than the global average."
The research was funded by the U.S. Department of Energy and by the National Science Foundation. It was conducted by scientists at NCAR, the University of Colorado at Boulder, and Florida State University.Title:
Weiqing Han: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, Colorado, USA;
Jianjun Yin: Center for Ocean-Atmospheric Prediction Studies (COAPS), Florida State University, Tallahassee, Florida, USA.Citation:
Lett., 36, L10707, doi:10.1029/2009GL037998Contact information for authors:
Peter Weiss | American Geophysical Union
Further reports about: > Arctic > Atlantic > Atmospheric > Atmospheric Research > Climate change > Geophysical > Geoscience > Greenland > Greenland ice > Melting rock > NCAR > Nature Immunology > Pacific Ocean > Sheet > computer simulation > conveyor belt > crystalline > fresh water > global sea level > global warming > ice sheet > ocean circulation > sea level > sea level rise
NASA eyes Pineapple Express soaking California
24.02.2017 | NASA/Goddard Space Flight Center
'Quartz' crystals at the Earth's core power its magnetic field
23.02.2017 | Tokyo Institute of Technology
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News