1. Nauru
Nauru is the smallest country in the world, covering 8 square miles. With about 10,000 residents, it is the second-least populated country after the Vatican City.
A coral reef surrounds the entire island, which is dotted with pinnacles made of phosphate.
Nauru's environment has been seriously harmed by phosphate-mining operations.
2. Mount Kilimanjaro
Africa's largest mountain is receding. The glaciers are melting because of deforestation and global warming.
3. Kiribati
Republic of Kiribati is an island nation consisting of 32 atolls and one raised coral island, dispersed over 1,351,000 square miles.
Coconuts have stopped growing on some islands, as salt water has flooded former freshwater areas.
4. The Marshall Islands
The Marshall Islands are made up of more than a 1,000 low-lying atolls, islands, and islets in the northern Pacific Ocean.
In 2008, waves and high tides caused flooding in the capital city of Majuro, located 3 feet above sea level.
5. Venice
Venice in Italy has long been sinking, but the frequency of floods increases each year.
6. Kosrae
Kosrae, in the Federated States of Micronesia, is experiencing coastal erosion.
7. The Poles
Ice decline has been rapid.
8. Carteret Islands
The Carteret Islands, northeast of Papua New Guinea, are low-lying islands.
The Islands have become inhabitable due to the combined effects of sea-level rise, erosion, storm surges, and saltwater contamination of the soil.
9. Solomon Islands
Made up of almost a 1,000 islands, the Solomon Islands have beautiful coral reefs, lagoons, and underwater volcanoes.
In addition to rising sea levels, cyclones and flooding are causing shoreline erosion.
10. Glacier National Park
Some scientists have predicted Montana's Glacier National Park will be glacier-free by 2020 due to climate change.
11. Seychelles
The Seychelles is made up of about 115 islands in the Indian Ocean. The Islands are surrounded by spectacular coral reefs.
The coral is what stops beach erosion, but rising water temperatures are causing the coral to die.
12. Tokelau
Tokelau is a territory of New Zealand that consists of three tropical coral atolls.
Rising sea levels and water temperatures are threatening the coral reefs and coastlines.
13. Kivalina
Kivalina is at the tip of an 8-mile barrier reef in Alaska. It is a traditional Inupiat Eskimo village with about 375 residents.
The city of Kivalina sued Exxon Mobil Corporation, stating that the large amounts of greenhouse gases they emit contribute to climate change and threaten the community's existence.
14. Maldives
The Maldive Islands in the Indian Ocean consists of thousands of small islands and atolls. The president of the Maldives announced the government would start buying land in other countries, including India, for citizens displaced by rising waters.
15. Tuvalu
Tuvalu in Polynesia comprises four reef islands and five atolls.
Tuvalu has suffered from flash flooding and freshwater shortages.
Prince William and Kate visited Tuvalu in September.
