IF YOU HAVE A

long list of places you want to see, it's time to start setting some priorities. Thanks to global warming, many popular travel destinations around the world are dramatically changing, says Christina Tunnah, director of marketing for guidebook publisher Lonely Planet. And not for the better. As the earth gets hotter, glaciers melt, sea levels rise and ocean temperatures increase. Here are six places you should visit now if you want to see them in all their glory.

1. Glacier National Park, Montana

Global warming is threatening at least a dozen of America's national parks, including Glacier National Park in Montana. Back in 1968 there were 38 glaciers inside the vast protected parkland. Today there are just 26.

By 2030 all of the park's namesake glaciers could be gone, according to the Natural Resources Defense Council and the Rocky Mountain Climate Organization. While these organizations don't claim to know all the harm that could be caused by the disappearance of the ice fields, one concern is a devastating increase in forest fires. Glacier National Park is home to more than 700 miles of hiking trails, 762 lakes and the famed Going-to-the-Sun Road, which offers a scenic drive over the Continental Divide.

2. Mount Kilimanjaro, Tanzania

One of the biggest draws in Africa is its highest peak, the famous snow-capped Mount Kilimanjaro. Located in Tanzania, the dormant volcano allows hikers to trek through what feels like four seasons in one day before taking in the stunning view of the surrounding plains from the summit.

If you want to see the storied snowy peak, you had better go before it melts. Since 1912, 82% of the ice fields have disappeared. And they could all be gone between 2015 and 2020 if the ice continues to recede at its current pace, according to Lonnie Thompson, professor of geological sciences at Ohio State University.

3. Churchill, Manitoba, Canada

The tiny Canadian town of Churchill is known as the Polar Bear Capital of the World. That's because in the autumn more than 900 descend upon its Hudson Bay shore waiting for the water to freeze over. Visitors can get up close and personal with the bears from the safety of guided tundra buggies or modified buses.

According to a study by the U.S. Geological Survey, two-thirds of the entire polar bear population could disappear in 50 years if the Arctic sea ice continues to melt at its current pace. Churchill's furry residents are already showing signs of environmental stress. Global warming is causing the Hudson Bay ice to break up three weeks earlier and freeze over two weeks later than it did 20 years ago. This shortens the animals' seal-hunting season and leaves them less nourished during the summer months.

4. Lake Mead, Nevada

Lake Mead is home to both stunning natural beauty and a man-made wonder, The Hoover Dam. Although it serves as a reservoir for parts of California and Nevada, this national park is also a respite from the desert heat and visitors enjoy boating, hiking, fishing and camping.

But Lake Mead's days may be numbered. Its water level is at its lowest in 40 years. While variation in elevation is normal, some scientists believe global warming is causing less snow and seasonal melting, which decreases water runoff into the lake. Indeed, there's a 50% chance Lake Mead will be dry by 2021 if the climate changes as expected and future water usage isn't curtailed, says a study by the Scripps Institution of Oceanography, University of California San Diego.

5. Mauritius

Located just east of Madagascar, Mauritius is a quiet tropical destination known for its impressive scuba diving. The island is ringed by a coral reef that managed to escape the worst of the 1998 heat wave that killed most of the corals in the Indian Ocean. But what wasn't destroyed by nature will likely get pummeled by man, says Thomas Goreau, president of the nonprofit Global Coral Reef Alliance. As the government shifts its economy away from sugar cane and toward tourism, increased sewage and sediment is already choking the coral. And while Mauritius has so far been lucky to avoid the worst of global warming, another hot year could finish off its reef entirely, says Goreau.

6. The Maldives

Another tropical paradise with a ticking clock is The Maldives, a tiny nation of roughly 1,200 coral islands southwest of Sri Lanka. Lonely Planet says this pricey destination could be the first to go on the global warming victim list. Indeed, the government of the Republic of Maldives says extreme weather is more frequent and destructive than in the past. And as climate change continues to push sea levels higher, the government worries that its land could become submerged. Its islands are just a few feet above sea level and during the 2004 tsunami only nine of the 200 inhabited islands didn't flood.