Archive for the ‘sea level’ Category

Transportation: Getting Around in a Changing World

March 13, 2008

The National Academies has just released a new study: Potential Impacts of Climate Change on U.S. Transportation . The study notes that transportation planners are still using historical data to guide their operations and investments.

“Transportation professionals should acknowledge the challenges posed by climate change and incorporate current scientific knowledge into the planning, design, construction, operation, and maintenance of transportation systems. Every mode of transportation and every region in the United States will be affected as climate change poses new and often unfamiliar challenges to infrastructure providers.”

The scientists down in Antarctica studying glacier melt note that the new IPCC report didn’t take Greenland or Antarctic glacier melt into consideration in their rising sea level projection. Studies have already come out, warning that the IPCC projection was much too conservative.

Scientists are funny people. A person has to listen closely to what they’re saying, and what they’re not saying. Scientists who are studying the West Antarctic Ice Sheet say that if it succumbs to warming, the oceans will rise from 3 to 5 meters. They talk in shocked tones about how quickly the WAIS is melting from underneath. They caution that more research needs to be done, a decade of research, and that few people have a clear understanding of the play between the Antarctic atmosphere and ocean.

The National Academies advise transportation professionals: “Climate warming over the next 50 to 100 years will be manifested by increases in very hot days and heat waves, increases in Arctic temperatures, rising sea levels coupled with storm surges and land subsidence, more frequent intense precipitation events, and increases in the intensity of strong hurricanes…

Potentially, the greatest impact of climate change on North America’s transportation system will be flooding of coastal roads, railways, transit systems, and runways because of a global rise in sea level coupled with storm surge and exacerbated in some locations by land subsidence. The vulnerability of transportation infrastructure to climate change, however, will extend well beyond coastal areas…

USDOT should take a leadership role along with professional organizations in the forefront of civil engineering practice across all modes to initiate immediately a federally funded, multiagency research program.…Federal agencies have not focused generally on adaptation in addressing climate change.”

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West Antarctic Ice Sheet and Ocean Upwelling

March 10, 2008

Science writer Marc Airhart writes in Geology: “The new IPCC reports on climate change had essentially sidestepped the issue of Antarctica’s potential contribution to sea level rise. The authors pointed out, rightly, that there was just too much uncertainty to make predictions.”

So what’s going on with study of the West Antarctic Ice Sheet? The new theory has to do with ocean upwelling.

“Antarctica is encircled by atmospheric currents that largely insulate it from the rest of Earth’s climate and keep it colder than it otherwise would be,” Airhart writes. These air currents push water away from the continent. “As surface water is pushed away, warm deep water rises to replace it.” The stronger the air currents, the more the upwelling. It looks like what is happening is that as the world climate warms, these air currents become stronger and there is more upwelling.

This is the hypothesis. There isn’t enough observational data to validate this hypothesis yet.

However, it has been observed that the antarctic glaciers aren’t melting from the top, they’re melting from underneath.  If the West Antarctic Ice Sheet lost it’s “plug”, the Thwaits Glacier, the rest of the WAIS might follow.

 NASA’s Dr. Jim Hansen predicts a 5 meter (16 1/2 feet) rise in sea level by the end of this century.  Back in 1991, the EPA estimated the cost of a one meter rise in sea level would be around $250-$500 billion dollars.  But the fact that this rise will  be happening everywhere all at once, in the midst of an economic recession … really, I have no idea of what the fallout of something like that would be.  It will be a disaster, but a disaster in slow-motion. 

Poor Projections

March 2, 2008

“The extent to which sea level could rise by 2100 is greatly underestimated in current models, suggests a new study, highlighting the risk faced by coastal areas and island nations.

Radley Horton at Columbia University, US, and colleagues estimated that sea level could rise by 54 to 89 centimetres by the end of the century, in contrast to the latest estimate by the Intergovernmental Panel on Climate Change (IPCC) of 18 to 59 centimetres. The team used a different approach to directly estimate rates of sea-level rise on the basis of model projections of ground surface temperature changes. The future sea-level rise predicted was mostly determined by the assumed rate of greenhouse gas emissions, suggesting that changes in emissions will be the main determinant of sea-level rise in the twenty-first century.

Neither these estimates nor those of the latest IPCC report take into account the recent acceleration of ice loss in the Greenland and West Antarctic Ice Sheets or the indirect effects of loss of Arctic sea ice cover, however. The scientists point out that current projections could therefore strongly underestimate the magnitude of sea-level rise in the coming century if ice loss continues to accelerate in polar regions.”

 

Take a look at rising water maps.