Updated

In 2007, UNESCO flagged the Galapagos Islands as an endangered place. But in 2010, after Ecuador's government stepped up conservation efforts, the Galapagos were dropped from the list. It's a story that gives us hope: With conservation efforts, funding, and a hefty dose of eco-focused TLC, we can turn potential disasters around. With that in mind, we researched places with unique features—wildlife, geography, culture—that would be devastating to lose. Once Africa's wild lions are extinct, for example, there's no replacing them. Ditto the island nations of the world, and the 9th-century buildings of Venice. Of course, it's impossible to rank these spots-how can you say, for example, that the Great Barrier Reef is more (or less) important than the Amazonian jungle? Instead, we put together a timeline that shows just how quickly we could lose these earthly wonders if we don't act now. Yes, this is a sobering read, but the silver lining is that you can make a difference-here's how (and how to visit responsibly if you so choose).

SEE THE PLACES

By the year 2100, we could lose...

Antarctica

Antarctica has no permanent residents, but its existence (or lack thereof) has major implications for everyone on earth. Over the past 50 years, temperatures in parts of the continent have jumped nearly 37 degrees—a rate five times faster than the global average. In 2007, the Intergovernmental Panel on Climate Change released a report predicting sea levels would rise between seven and 23 inches by 2100. One caveat: the numbers didn't account for Antarctica's rapid ice melt. Now, researchers believe the sea could shoot up three to six feet by the end of the century. Antarctica's ice cap holds 70 percent of the freshwater on Earth; if it melts, the oceans could rise 187 feet, decimating entire island nations worldwide (the Maldives, for example). Antarctica's wildlife is also at risk. Krill are essential to the marine food chain—fish, seals, and whales eat them—but the shrimp-like crustaceans' numbers have dropped 80 percent since the 1970s, disrupting the whole ecosystem.

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Donate: Comprised of more than 30 NGOs worldwide, the Antarctic and Southern Ocean Coalition pushes initiatives like tourism regulation, and sustainable fishing. asoc.org

Go green: G Adventures, a sustainability minded tour operator based in Canada, offers a 13-day Antarctica cruise staffed by historians and marine biologists aboard the M/S Expedition. 888/800-4100, gadventures.com. From $4,999 per person.

Venice, Italy

One of the world's most beautiful, historic, and romantic cities is built on water—and it could soon find itself under it. Rising ocean levels resulting from global warming are a threat to the low-lying Venice, which is made up of 118 small islands on a lagoon that sits at sea level. Flooding from the Adriatic Sea's high tides has become dire in the last 60 years. In 1900, Piazza San Marco, Venice's central square, flooded seven times; in 2002, the number jumped to 108. The ocean's salt water eats away at Venice's historic buildings, among them the opulent Palazzo Ducale, which dates back to the 9th century. Floodgates are being built around the city, but they're not scheduled to begin operation until 2015. Water isn't the only thing flooding the city. Twenty million tourists visit the city annually, which encourages harmful real-estate development and jams Venice's waterways with traffic. Advocacy group Venice in Peril estimates that the city may be largely unlivable as early as next century.

Donate: Since 1966, Venice in Peril has spearheaded research on how to protect the city from flooding, as well as worked to restore Venice's monuments, buildings, and artwork. veniceinperil.org

Go green: If you really want to help Venice, don't visit. If you must go, though, go smart. Canonici de San Marco is a complex of eco tents eight miles outside of Venice, where you can bike in the countryside or take day-trips into the city (011-39/348-722-5577, viacanonici.com. From $157 per night including breakfast and transfers from the Mirano train station). The water that surrounds the city shaped its past-and is in control of its future. Laguna Eco Adventures offers tours of the lagoons on traditional wooden boats, powered by towering sails (011-39/329-722-6289, lagunaecoadventures.com. From $52 per person for a two to four-hour lagoon tour).

By the year 2070, we could lose...

The Himalayas

Like Antarctica, the Himalayas are covered in ice and snow. In fact, the world's highest mountain range—which runs 1,500 miles through seven countries, including India and China—contains the planet's largest non-polar ice mass, with over 46,000 glaciers. And just like in Antarctica, the ice is melting. Between 1950 and 1980, about half of the Himalayas' glaciers were shrinking. That number hit 95 percent in 2010, and scientists predict that the entire Himalayan land mass may be slashed 43 percent by 2070. Global warming is just one reason—soot from millions of coal- and wood-burning stoves in India and China also take a share of the blame. The glaciers absorb the heat, which exacerbates the warming process. The glacier loss will affect people living along Asia's 10 major rivers—who make up one-sixth of the total global population-that depend on glacial melt to stave off drought and starvation.

Donate: Founded by an Arizona man in 2009, the Himalayan Stove Project has an ambitious goal: Deliver 10,000 clean-burning, fuel-efficient stoves to Himalayan residents by 2014. himalayanstoveproject.org

Go green: Himalayan Eco Treks, which operates out of Nepal, organizes an array of earth-friendly trips, including a 25-day Best of Everest tour that includes eight days of trekking as well as easier days seeing cultural spots like the ancient town of Bhaktapur, a World Heritage site. 011-977-4/266-382, himalayanecotrek.com. From $2,765 per person for the 25-day tour.

By the year 2040, we could lose...

Wine Regions

The extreme heat waves and frosts that come with climate change affect soil conditions, so much so that the world's most prestigious wine regions from Bordeaux to Rioja to Napa Valley could be unable to grow quality grapes by the end of the century. To put it in perspective, temperatures in California's Napa (home to 45,000 acres of vineyards) could jump two degrees in the next 30 years, which would upset the balance of sweetness and acidity crucial to good wine, and essentially shrink America's most famous wine-producing region by 50 percent. The conditions are so extreme in Europe that long-established wine epicenters could be pushed northward to England and Scotland as continental temperatures rise. In fact, Brits are already ramping up the production of sparkling wines, traditionally the domain of France's Champagne region: In 1990, England was home to 140 acres devoted to sparkling-wine grapes; by 2010, the number spiked to 1,360.

Donate: Helping wine regions around the world is easy: Buy a bottle. The more money pouring into wine regions, the stronger the local economy--which means winemakers can invest in research and technology to keep their grapes healthy.

Go green: Napa Valley Reservations shuttles drinkers between four eco-friendly wineries in a fuel-efficient Mercedes-Benz Sprinter. 707/252-1985, napavalleyreservations.com. From $130 per person.

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By the year 2030, we could lose...

African Lion Habitats

Africa's wild lions have it especially rough: In the last 50 years, the continent's population plummeted from 450,000 to about 40,000, a drop of around 91 percent. The culprit: People. Africa could be home to 1.75 billion people by 2050. As Africa's human population explodes, the competition for resources (think food) increases while farmers and ranchers encroach onto the lions' territory. According to the University of Minnesota's Lion Research Center, Africa's lions may not survive into the next century; other experts say they could be gone in 20 years.

Donate: The Lion Conservation Fund raises local awareness about lion conservation and restores and protects the animals' habitats. lionconservationfund.org

Go green: Minnesota-headquartered Kuchanga Travel organizes "volun-tourism" trips to Zambia, where participants gather data on the country's wild lions and help guides care for the animals. Activities include educating local students about conservation and going on lion walks--literally strolling with the animals in the wild. 612/432-4473, kuchangatravel.com. From $2,080 per person for a two-week trip.

The Amazon

At current deforestation rates, 55 percent of the Amazon's 1.4 billon acres of rain forests could be gone by 2030. (Overexpansion of agriculture, illegal logging, and climate change are all to blame.) The rain forests, which are home to 30 million indigenous people and one-tenth of the world's known species, also contain up to 140 billion metric tons of carbon, which helps stabilize the global climate.

Donate: Founded by a pair of tropical ecologists in 1999, the Amazon Conservation Association works to protect the region's biodiversity. amazonconservation.org

Go green: Ecuador-based Tropic introduces visitors to the Huaorani, an indigenous Amazonian tribe whose members lend tips on tree climbing, kayaking nearby rivers, and face painting with achiote paste. Travelers bunk at an eco-lodge run by the Huaorani, and meals are crafted from local produce. 202/657-5072, tropiceco.com. Five-day trips from $860 per person.

The Alps

Increased carbon dioxide emissions are causing glaciers in the Alps to melt rapidly; according to scientists, most of them could be gone by as early as 2030. In some areas of the 600-mile mountain range, glaciers are shrinking by 3 percent every year. This obviously has dire implications, both in terms of physical catastrophes (massive flooding, which would impact the Alps' 13 million residents) and economic disasters (the Alps thrive on ski tourism, with more than 120 million annual visitors). In 2006, a Swiss ski-resort owner devised a creative solution to keep glaciers cold: He wrapped one in a 43,000-square-foot fleece blanket. Other resort owners soon followed suit and scientists have since experimented with wool, hemp, and plastic coverings. Also at stake: the region's 30,000 animal species and 13,000 plant species.

Donate: The World Wildlife Foundation's European Alpine Program is dedicated to preserving the region's biodiversity. wwf.panda.org

Go green: If you're traveling with Utah-based Alpenwild, expect to use public transportation, sleep in local inns--and see incredible scenery. The company's Best of the Alps tour leads hikers through lush forests and picturesque villages before hitting Zermatt, at the base of the Matterhorn, and the Jungfrao Mountains, home to the Aletschgletcher, Europe's longest glacier. 800/532-9488, alpenwild.com. From $3,495 per person.

By the year 2020, we could lose...

Virunga National Park, Democratic Republic of the Congo

Founded in 1925, Africa's oldest national park covers nearly two million acres and includes savannas, swamps, and ice fields. It also contains the highest biological diversity of any national park in Africa, with 2,000 plant species, 706 bird species, and 218 mammal species, including hippos and one-third of the world's mountain-gorilla population. Virunga has been in trouble for nearly 20 years—poaching and habitat destruction are to blame—but a huge problem is its location: it sits near a war zone. The park lies within the Democratic Republic of the Congo, but borders Rwanda. Rebel soldiers from the Forces for the Liberation of Rwanda (believed to have been involved with the Rwandan genocide in 1994) operate within the park, and more than 140 rangers have been killed in the line of duty since 1996. Virunga's hardwood forests are also being destroyed to support an illegal charcoal trade—if that keeps up, most of the trees in southern Virguna will disappear in 10 years.

Donate: Give directly to Virunga National Park; your money goes towards guarding mountain gorillas (you can pick an individual animal or an entire gorilla family to protect) and other conservation efforts. gorillacd.org

Go green: Safely visit the park with Congo-based Kivu Travel, which offers a five-day Gorilla and Volcano tour that includes a climb up the Nyiragongo volcano and a visit to Virunga's gorillas. kivutravel.net. From $1,650 per person.

Great Barrier Reef, Australia

Stretching 1,429 miles, Australia's Great Barrier Reef is the world's largest and most diverse reef system—and it could be gone in 100 years. Coral cover alone has been reduced by half in the last 50 years, and the GBR as a whole only has a 50 percent chance of survival if global CO2 emissions aren't cut by at least 25 percent by 2020. It's no surprise, then, that climate change is partly to blame. (Another culprit: agricultural run-off from farms, which affects water quality and creates algae blooms.) When the ocean warms up, the higher temperatures harm the more than 2,900 coral reefs, along with its 1,500 species of fish, 134 species of sharks and rays, 30 species of marine mammals like whales and dolphins, and 23 species of marine reptiles, including sea snakes and turtles. According to the World Wildlife Fund, more than 1,000 starving turtles washed up on Australian shores in 2011. Their main food source, sea grass, had been wiped out by erratic weather like floods and cyclones. Australia's economy also depends on the reef: Industries like tourism and fishing rake in an annual $5.4 billion and employ 63,000 people.

Donate: Australia's Great Barrier Reef Foundation funds environmental research and conservation efforts. barrierreef.org

Go green: Australian eco-tour company Quicksilver runs day-trips from Queensland to the Great Barrier Reef on high-speed catamarans. Once there, you can dive, snorkel, and watch marine life from an underwater observatory. 011-61/7-4087-2100, quicksilver-cruises.com. From $228 per person.

Any moment now, we could lose...

Machu Picchu, Peru

UNESCO called Machu Picchu's problems "urgent," and rampant tourism is the biggest threat to Peru's main attraction. Last year marked the centennial of Machu Picchu's "discovery" by Yale history lecturer Hiram Bingham; 1 million visitors descended on the site, up 30 percent from 2010. With more visitors comes more construction in nearby towns like Aguas Calientes (already packed with hotels and restaurants), straining the fragile land: riverbanks are erosion-prone, and landslides and fires also threaten the site. Ironically, Peru's economy depends on visitors. About 90 percent of the country's tourist revenue this region, and 175,000 local people make their living directly from Machu Picchu tourism. When heavy rains and landslides forced the site to close for two months in 2010, a $200 million loss ensued. Losing Machu Picchu is more than economic. Built as an Andes Mountain retreat for Incan ruler Pachacuti in 1450, the stone city is packed with clues that shed light on ancient Incan civilization. Archeological efforts are still ongoing, and new discoveries include cemeteries, roads, and a series of agricultural terraces.

Donate: The World Monuments Fund, which advocates for endangered sites across the globe, added Machu Picchu to its 2010 watch-list. whc.unesco.org

Go green: On Conservation VIP's 10-day volun-tourism trip, participants help local park rangers with archeological restoration and maintenance of the Inca Trail. 952/228-5946, conservationvip.org. From $2,850 per person.