Whale Skate Island in the Northwest Hawaiian Islands was a tiny dot of land in the vast Pacific, about 10 to 15 acres in size. It was covered with vegetation, nesting seabirds, Hawaiian monk seals and turtles laying eggs. It no longer exists.
"That island in the course of 20 years has completely disappeared" with rising sea levels, said Beth Flint, a U.S. Fish and Wildlife Service wildlife biologist for the Pacific Remote Island Refuges. "It washed away."
And with it went habitat for the birds, seals and turtles, who had to find other islands or die, in one of the more dramatic illustrations of how global warming might be affecting Earth's species and their habitat.
Warming temperatures are melting away feeding grounds from polar bears, wiping out a small-animal population in the western United States and choking the world's coral reefs, some scientists suggest.
Millions of other species are at risk of succumbing to the elevated temperatures or being forced to search for cooler environments, they say.
"There are a lot of threats to biodiversity on a local scale, but global climate change is a very broad threat that's affecting ecosystems all around the world," said Lara Hansen, chief scientist for the climate change program at the Washington, D.C.-based World Wildlife Fund. "It's happening at rates that defy evolution and adaptation."
Hansen testified last month before the Senate Commerce Committee on the effects of climate change, and said climate change "is arguably the greatest threat to the world's biodiversity."
"Those numbers being impacted rival or exceed the only other major thing that we know that is this broad, and that's habitat destruction," she said in an interview.
The Intergovernmental Panel on Climate Change said the average global temperature has risen by 0.6 degrees Celsius in the past century. The group of 2,500 scientists is sponsored by the United Nations and the World Meteorological Organization.
Considering many species are already living at their thermal maximum, even the slightest temperature increase is significant, Hansen said.
The American pika, a distant relative of the rabbit, might become the first known North American mammal to fall victim to warming, she said.
Pikas, which resemble hamsters, live in cool and moist areas of Washington state, Oregon, Idaho, Montana, Wyoming, Colorado, Utah, Nevada, California, New Mexico and British Columbia.
A study published last year in the Journal of Mammalogy said climate change may have contributed to the extinction of the pika populations in the Great Basins over the past several decades.
Erik Beever, lead author of the study, said pikas have vanished in two more locations since the study was published. Now, pikas have vanished in nine of 25 sites where they were previously documented.
"That suggests to me that these losses are happening relatively quickly," he said. "I suspect these other populations are pretty vulnerable in the future."
Beever, of the U.S. Geological Survey's Forest and Rangeland Ecosystem Science Center in Corvallis, Ore., said while there is evidence showing that climate change "seems to be a strong driver" of the pika disappearance, other potential factors include changing habitat area, proximity to roads and presence of livestock grazing.
In the Arctic, polar bears are losing their sea ice, limiting their seal-hunting range, Hansen said. Since the ice season is also becoming shorter, polar bears are having longer periods of fasting, she said.
"As a result, we see them in worse condition," she said. "They are smaller and have less reproductive success."
Coral, a living creature of the sea, is among those affected by slightly warmer water temperatures. Warmer water can cause coral bleaching, or the death of the organism. The colorful tissue of the corals is stripped away, leaving behind the bone-white skeleton.
Jim Maragos, a coral reef biologist with the U.S. Fish and Wildlife Service in Honolulu, has studied corals surrounding the Hawaiian Islands chain and U.S. territories in the Pacific.
"At all of our refuges in the remote Pacific Islands over the last 20 years, there's been at least some coral bleaching," he said. "These are places that have no people. There's no other excuses except for that there was warm temperatures. So we know that warm temperatures caused it. What we don't know is what's causing the warm temperatures."
Jeff Palovina, acting director of the NOAA Fisheries Pacific Islands Science Center, said it will take many years before scientists can say with confidence that global warming is the sole reason for the bleaching. It could be caused by El Nino-La Nina ocean currents, general variability, or it might have been happening for years before people noticed it.
"We know there's more observation going on now than there were 20 years ago in the Northwestern Hawaiian Islands," he said. "So we don't know if we missed episodes of coral bleaching in the past. It'll take a lot longer to be able to say it's one cause or another."
From the pristine waters off Maui to the lush rain forests on the Big Island, Hawaii is home to thousands of rare plants and animals. Of more than 22,000 known species in Hawaii, 8,850 are found only on the islands, according to the Hawaii Audubon Society.
Many might be at risk. Warmer temperatures in Hawaii are believed to have allowed mosquitoes to climb higher on the islands' mountainsides, carrying avian malaria with them to attack native birds.
Mosquitoes "continue to plague Hawaiian honeycreepers, endemic species that have been crowded into high-elevation forests on the upper edge of their former range due to habitat destruction by humans and other introduced species," according to a study prepared by the Honolulu-based East-West Center for the U.S. Global Change Research Program.
"Climate change, therefore, has direct effects on Pacific island species and ecosystems, and it is very likely that its effects are multiplied" by other human activities that affect habitat, the study said.
Warming might expand the habitat and infectivity of disease-carrying insects, increasing the potential for transmission of diseases such as malaria and dengue fever, according to an Environmental Protection Agency report, "Climate Change and Hawaii."
But some scientists are reluctant to place the blame on global warming and say any changes in biodiversity in the Pacific could be linked to the El Nino-Southern Oscillation cycle.
"To be very frank, no one can demonstrate that global warming has had any effect on our biodiversity here," said Fred Mackenzie, a University of Hawaii professor of oceanography, geology and geophysics. "It can have tremendous impact, but I would like to see the evidence that says it has had an impact."