That dream vacation - diving along the Great Barrier Reef, skiing in the Swiss Alps - could remain a dream forever if you don't get a move on.

The brilliant coral off the coast of Australia could be largely gone by 2050, says a 2007 report by the Intergovernmental Panel on Climate Change. And rising temperatures in the Alps are already forcing operators to invest in more snowmaking equipment, says Forbestraveler.com. The attention lately focused on these changes, and the overall issue of global warming, has already prompted one latter-day oracle to predict we will travel differently this year and beyond.

"Let's face it, Al Gore's An Inconvenient Truth and the time-lapse photography were not lost on a number of people," says Ann Mack, director of trend-spotting for JWT, the nation's largest advertising agency. "And increasingly, people are wanting to see these sights of the world before they change shape or change form. As global warming is rising up the world's agenda, ecotourists are flocking to previously ignored places."

It's been called climate sightseeing, a kind of farewell tour of Earth's greatest hits. Hard data is not available - determining exactly why people go where they do is next to impossible. But a clear interest in ecotourism, coupled with much greater accessibility to places such as the Earth's poles, means more people are visiting far away and endangered sites, whatever their motives.

The subject is full of paradoxes: The more you travel, for example, the more you're contributing to the problem that made you go to an endangered site in the first place. And some places - Canada, perhaps Russia and other cold climes - are likely to attract more tourists as they warm.

Robert Henson, a meteorologist at the National Center for Atmospheric Research and author of The Rough Guide to Climate Change, says: "Stay longer. Go ahead and travel, but do it smartly. Get direct flights; use a train to get around."

Here is a short list of places that scientists and key reports say are feeling the effects of global warming today - places to consider as you put together your travel plans.

Glacier National Park, Montana

Scientists say the glaciers will be gone by 2030. The U.S. Geological Survey has been keeping a close eye on Glacier for a long time - the park is the site of one of the nation's most important research programs on climate change. Photos from the early 1900s up to today show glaciers receding for decades - and the weather there is on a wild ride, with record droughts, near-record summer temperatures and near-record snowfall. Though it's unclear whether this decade's changes are speeding up the glaciers' decline, there's no doubt they're receding. Glacier is a huge park, with more than 700 miles of trails through pristine forests. To learn about the park, go to nps.gov/glac/index.htm.

Alaska

Most of the many glaciers here are also receding, with a few minor exceptions, and have been for 15 to 20 years, says Ron Peck, president of the Alaska Travel Industry Association. The traveler's challenge here may be fighting the crowds. Peck says Alaska counted 1.7 million visitors last summer, up 3 percent from the previous year. Travel to Alaska has changed drastically during the past 20 years, says Steve Cosgrove, owner of Dynamic Travel in Southlake. "The average tour was a salmon bake and a totem pole tour. Now there's river rafting, scuba diving - it's a completely different experience now."

A lot of people arrive on cruise ships - in 2006, Alaskan ports had 3.3 million cruise-passenger visits (that's probably about three times the actual number of passengers, because each passenger visits several ports on a cruise.) Find more information at travelalaska.com.

New England

Henson says a "fair amount" of research shows the sugar maples so beloved for their brilliant foliage and maple syrup are in some danger during the next few decades. On the other hand, a report in July by scientists in Cambridge and the Union of Concerned Scientists says the hardwoods that make up the classic New England forest scenery "may be able" to last the century. Spruce and fir trees are in more danger of going away over time.

Either way, the forests themselves would change drastically as temperatures rise and different trees become dominant, the report says. Some of the area's songbirds are likely to take flight for cooler climes - the song sparrow, Bicknell's thrush, Baltimore orioles. Other species such as the great horned owl might not be affected and might even increase. And delicious New England maple syrup? Some production has already shifted to Canada for technological and tree-related reasons, Henson says.

Western pine forests

This is mostly the fault of the mountain pine beetle, "a little critter that gets in and messes with the flow of the sap to the tree," says Henson, who lives in Colorado. These beetles have been running amok lately in parts of the West that haven't had consecutive cold winters. And they're on the move over the Continental Divide from western Colorado, Henson says.

Already, Henson says, he sees big stretches around Aspen and Glenwood, Colo., on U.S. 70 west of Denver, where the trees' pine needles are red. This isn't a normal change. The trees are dying, and they won't regrow for decades. New Orleans

It's been sitting on a swamp for years, and that's not going to get any better. Henson also worries about the impact of recovery from Hurricane Katrina: "The Netherlands is already kind of resigned to the fact they're going to have to build giant dikes around the country," he notes. "New Orleans is more in the classic rebuilding mode."

Without getting into the political problems that may have hindered the city's recovery, suffice to say climate change is going to pick up the pace of any encroaching water. The French Quarter has been fine to visit since shortly after Katrina, with plenty of the renowned, great restaurants and hotels open. Henson was in the Crescent City in late January and said a two-hour Gray Line tour is a great way to see what's happened and how recovery is progressing. Travelers who like to give back to their destinations still have plenty of opportunities - city residents still need help rebuilding homes, for example. Find information at nola.com.

The Everglades, Florida

According to the Natural Resources Defense Council, an environmental action group, "the anticipated 2- to 3-foot rise in sea level over the next 100 years will cause salt water to flow 10 miles or more inland - right into the Everglades." Researchers also are predicting more tropical storms, which is more bad news for Florida.

The vulnerable and fragile Everglades are on travel.msn.com's list of "World's Endangered Destinations" and mentioned frequently in climate-change discussions because they are changing in ways that could happen in other coastal areas. For details on Everglades National Park, go to nps.gov/ever.