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Even as the final touches of the IPCC report, scheduled to be released on February 2, are being hammered out, CNN.Com (from an AP report, February 29, 2007) notes that scientists are aready warning that the IPCC report does not adequately address the impacts on sea-level rise of melting Polar ice sheets:

"...The early versions of the report predict that by 2100 the sea level will rise anywhere between 5 and 23 inches. That's far lower than the 20 to 55 inches forecast by 2100 in a study published in the peer-review journal Science this month. Other climate experts, including NASA's James Hansen, predict sea level rise that can be measured by feet more than inches.

The EPA offers extensive information on the potential effects of sea-level rise.

"Do We Need to Do Anything About Sea Level Rise Now?

The primary mission of the EPA Sea Level Rise reports has been identifying instances where it is rational to prepare now for the coastal consequences of climate change, even though most of those consequences are decades away--or more. The Overview Chapter in the 1984 publication Greenhouse Effect and Sea Level Rise: A Challenge for this Generation outlines the case for taking adaptive actions: At least some global warming and accelerated sea level rise are inevitable because of historic emissions, the inertia of the oceans, and the economy's current dependence on fossil fuels. (In the mid-1980s there was not yet a consensus that the global surface temperature is rising.) Therefore, communities and individuals will have to eventually adapt to consequences of global warming such as sea level rise. The primary question is whether to wait or take action now. The chapter on "...Before and After a Coastal Disaster" shows that the decision whether to rebuild after a coastal disaster might depend on whether property owners believe that they can rely on the government to fund efforts to hold back the sea. The Economics Chapter estimates the possible costs of sea level rise for Charleston and Galveston, and concluded that anticipating sea level rise could cut in half the eventual costs. In the Forward, EPA's original Administrator, William Ruckelshaus, points out that democracies often find it difficult to prepare for looming problems until a catastrophe occurs. "The ultimate danger is that by remaining reliant on "the catastrophe theory of planning" in an era producing catastrophes of a magnitude greater than in the past, we can place our institutions in situations where precipitate action is the sole option – and it is then that our institutions themselves can be imperiled and individual rights overrun."

Scientists from NCAR and UCAR are among those who are responsible for the IPCC report coming out in February. The Rocky Mountain News (January 20, 2007) interviewed them on the process and the results:

"Change will last centuries

The concept of climate-change commitment has been around for about 20 years. What's new is that some of the latest, most sophisticated climate models now confirm the dire predictions of earlier, cruder simulations.

In a 2005 report in the journal Science, NCAR researcher Tom Wigley said that even if greenhouse gas levels could be magically stabilized today, sea levels would rise 10 to 20 inches per century for the next 400 years or more, imperiling coastal regions.

The Arctic Sea ice

The floating sea ice of the Arctic covers an area equal to that of the United States. The permanent presence of sea ice, ice sheets, and continuous permafrost are unique features of the Polar Regions. Even though it is characterized by its harsh environment and vast landscapes the Arctic serves as the home of many forms of life, including organisms living in the ice, fish and marine mammals living in the sea, birds, land animals such as polar bears, and human societies. But much more than that, its white ice cover reflects huge amounts of sunlight and thereby helps the world stay cool.

Today the latest state-of-the-art climate models include as many physical, biological and chemical processes as possible. The models are based on mathematical equations that describe the behaviour of the atmosphere and ocean, and their complex interactions with other components of the Earth system, such as the land surface, the biosphere (animals, plants and microbacterias) and the cryosphere (ice mass, such as glaciers and ice sheets). Their core goal is to describe how certain variables in the coupled atmosphere-ocean system, such as temperature, air pressure, winds or ocean currents, have changed in the past and will most likely change in the future. But the climate system is very complex and understanding or predicting climate changes in the future is a very difficult thing to do. And with weather forecasts becoming inaccurate after just a few days, one can easily ask how we can even claim to project most likely weather conditions in the future?

National Geographic News (December 14, 2006) reports on a new study of potential sea level rise in this century. "[T]he physics of how ice sheets melt and how the oceans will expand in a warmer world is still poorly understood.

So Stefan Rahmstorf, an ocean physicist at Potsdam University in Germany, took a different approach: He used studied actual observations of changes in sea level collected in the 20th century to make predictions for the 21st century.

Current models don't jibe with actual sea level rise during recent decades, Rahmstorf says. So he crafted a formula based on a relationship between global temperature and sea level seen during the past hundred years.

Reuters
Sunday, December 10, 2006 22:49 IST

In the Antartic summer, scientist work around the clock to uncover the past of this ice-clad landscape, in order to better predict its future, and the future of the planet: "Antarctica is a prime place for this research because it serves as an early warning system for climate change and is a major influence on global weather.

Because about 90 per cent of the world’s ice volume and 70 per cent of its fresh water is on the southernmost continent, any substantial warming could cause a rise in sea levels around the globe. Tom Wagner of the US National Science Foundation said, 'Its ice sheets are the main player in sea level rise; there is already evidence that they are shrinking.'"

Scientists at the annual meeting of the American Geophysical Union presented a new warning on global climate change. "Global warming could melt the Arctic's ice during the summer as early as 2040, raising serious environmental as well as commercial and strategic issues, experts said on Monday.
'The effects of greenhouse warming are starting to rear their ugly head,' said Mark Serreze, a scientist at the National Snow and Ice Data Center at the University of Colorado in Boulder.

"Investigators from the ARC Centre of Excellence for Coral Reef Studies (CoECRS) consider the reef – the most southerly coral reef yet known – is a harbinger of what could happen again as global CO2 levels and temperatures rise during the 21st century.
'We’ve dated the reef to about 128-125,000 years ago, right in the middle of the last interglacial, or the last period of global warming before our most recent ice age,' says Professor Malcolm McCulloch, deputy director of CoECRS and an earth scientist at The Australian National University.
'The reef lies about 2.5 metres above the current high tide zone, which means that for it to survive and grow, sea levels would have had to be at least 3 to 4 metres higher than at present.

The work of J.T. Overpeck at the University of Arizona and Bette Otto-Bliesner of the National Center for Atmospheric Research in Boulder, Colorado points to the features of the current climate that make this look like a climate in the past when sea levels were six meters higher. "Although ice sheet disintegration and the subsequent sea level rise lags behind rising temperatures, the process will become irreversible sometime in the second half of the 21st century, Overpeck said, 'unless something is done to dramatically reduce human emissions of greenhouse gas pollution.

'We need to start serious measures to reduce greenhouse gases within the next decade. If we don't do something soon, we're committed to four-to-six meters (13 to 20 feet) of sea level rise in the future.'"