But here's an inconvenient truth that's really scary: Gore may be right about a lot of things, including Greenland's rapid rate of melt and Florida flooding, along with a good stretch of the U.S. Gulf Coast, including New Orleans.

This should be sobering for Alaskans, who are already seeing the effects of increasing storms, coastal erosion and permafrost thaw, which scientists say are related to climate change.

Robert Corell was in Anchorage recently and gave several eye-opening lectures on climate change. Corell is a leading U.S. oceanographer who helped lead the United Nations Intergovernmental Panel on Climate Change, and who stood beside Gore in Oslo to receive the Nobel Peace prize awarded jointly to the former vice president and the IPCC science team.

Corell chaired the Arctic Climate Impact Assessment team, a part of the IPCC effort. He is a former professor at the University of New Hampshire and also directed the National Science Foundation's global climate change program.

In his talks in Alaska, one of Corell's main points was that the warming trend appears to be racing ahead of the modeling that scientists have done, as evidenced by recent polar ice surveys. Humankind may soon be experiencing climate and environmental changes that can't be predicted, Corell said at the conclusion of a talk at the University of Alaska Anchorage May 1.

That the warming trend is occurring is now commonly accepted, although a small number of scientists still believe natural causes may be as responsible for warming trends as man-made causes.

Still, most scientists now accept the IPCC's conclusions, including the belief that warming is caused or strongly influenced by human activities. The models have been put together over several years and reviewed by about 2,500 scientists, and the conclusions are now accepted by 140 nations, including the U.S.

But even if emissions of greenhouse gases were to be sharply curtailed immediately the buildup of carbon dioxide will continue for a long time, and the warming of the atmosphere even longer.

Corell said the buildup of CO2 will continue toward a peak in perhaps 100 years, but even then, carbon dioxide levels would not stabilize in the atmosphere for several hundred years, and the warming trend caused by the buildup will not end for about 500 years have passed. Even then, the atmospheric warming effects of higher temperatures in the ocean will continue, Corell said.

Northern regions like Alaska are already feeling the effects. Alaska's average statewide temperature has increased 3.4 degrees Fahrenheit since the 1950s and the winter average has increased even more, by 6.3 percent, according to data compiled by the University of Alaska Fairbanks' International Arctic Research Center.

The effects have been easy for Alaskans to observe.

“Higher temperatures of recent decades have been associated with an earlier snowmelt in spring, a reduction in summer sea ice coverage, a retreat of many glaciers and a warming of permafrost,” John Walsh, director of UAF International Arctic Research Center, told the U.S. Senate Commerce Committee in a May 8 briefing.

Walsh's group at UAF is working to refine global climate models so that regional effects in places like Alaska can be predicted with more certainty. Useful information for Alaskans would include predictions on firmness of the ground for surface transportation, snow cover characteristics and vegetative dryness during fire season.

Efforts are also underway to understand how “feedback” effects can be incorporated into the models.

“Feedbacks between ice, snow and the atmosphere exert potentially strong leverage on high-latitude climate change, and these feedbacks introduce large uncertainties into simulations by existing climate models,” Walsh told the senate committee.

Unfortunately, the uncertainties may mean that the models are too conservative.

“The recent retreat of summer sea ice (in the Arctic Ocean) is occurring at a faster rate than projected by any of the models” developed by the IPCC, he said. In parts of Alaska early spring snow melt-off may be resulting in increased vegetation.

In his UAA lecture Corell said that the current global models can reasonably be expected to predict temperature changes in the next 100 years because they have accurately verified changes over the last century for which there is real temperature data. After 100 years, all bets are off, he said.

The Earth has seen dramatic changes before. There was even a time 600 million years ago when the entire planet was covered with ice. Scientists now believe the more recent ice ages, which saw much of the northern hemisphere covered by glaciers, were caused by periodic shifts in the earth's orbit.

The last 10,000 years, however, have seen exceptionally stable climate conditions with a range of temperature variation of 0.7 degrees Centigrade from the average, a comfortable and stable environment for the development of agriculture, society and civilization, Corell told his UAA audience.

Global temperature measurements show we are now moving rapidly out of that comfortable temperature band, he said. Present-day temperature averages are at the top of the band. On average, global temperatures have increased 0.74 degrees C over past 100 years, according to the IPCC reports.

Effects that are already appearing include increasing drought in certain regions like the U.S. Southwest and changes in storm patterns and storm intensity. These will affect agriculture, and some of the current food supply shortages and price increases may be related to climate change.

“The effects on the food system are expected to get worse as temperatures increase beyond 1 percent,” Corell said.

The models predict a temperature increase of 1.5 degrees C to 4.5 degrees C with the most likely increase being 2 degrees C to 3 degrees C, he said.

Climate change models have become much more sophisticated and complex. In the 1970s, the models included mainly atmospheric changes, while they now include changes induced by changed ocean conditions and increasing levels of pollutants, such as sulfur emissions.

The generation of models used in the IPCC's forecasts were developed in the 1990s and their conclusions already appear to be too conservative.

Actual changes - the rapid retreat of summer Arctic sea ice and the buildup of carbon dioxide in the atmosphere - appear to be accelerating faster than predicted.

CO2 content currently is 379 parts per million. Models predict an atmospheric CO2 content of 450 ppm by 2025 to 2030, but measurements of a 1.9 percent increase in world CO2 emissions in 2002 indicate that this buildup is occurring at a faster rate, and that 450 million ppm could be reached by 2020.

Rising ocean levels must also be considered. Melting of the Greenland and Antarctic ice sheets would cause only part of this, Corell said. Much of it will likely come from natural expansion of the water as it warms.

Average sea levels have increased an average of 8 centimeters (3 inches) over the last 20 years and Corell said most scientists believe a 1-meter increase in sea levels to be most likely in next 100 years. This is enough to inundate parts of southern Florida and a good stretch of the U.S. Gulf Coast, including New Orleans, he said.

Some scientists predict ocean level increases of up to 4 meters. This more pessimistic view results from a recent study of the last interglacial warm period initiated by the European Commission. This period spanned about 1,000 to 1,500 years between two ice ages. The temperature increase was 1 degree C on average but the ocean level increase was estimated at 4 meters, Corell said.

If Greenland were to entirely melt, which the models indicate could eventually happen, the sea level increase is estimated at about 7 meters, or 23 feet.

The science teams also feel, with 95 percent certainty, that the warming is caused or strongly influenced by the buildup of greenhouse gases from industrial activity.

“We have measured a dramatic buildup of carbon dioxide, methane and nitrogen oxide in the atmosphere over the last 150 years,” essentially since the beginning of the industrial revolution, Corell said. “Something is clearly different.”

Using the global climate change models, computer simulations were done for regions of the world assuming no greenhouse gas buildup, as if the industrial revolution had never happened.

In his UAA lecture Corell showed those and compared them with simulations that took the base case (no greenhouse gases) and added effects induced by the buildup of greenhouse gases in the atmosphere. The correlation between the predicted temperature buildups in different regions and the actual temperatures measured was startling.

In the climate change discussion, much of the attention is focused on carbon dioxide, but methane is a gas that is 25 times as potent as CO2 in its greenhouse effect and methane emissions are not being measured in the U.S., although they are in Europe.