Climate data from more than 7,000 weather stations around the world shows 2005 has tied 1998 as the warmest year ever, since reliable records were kept in the 1800s.
Winter hides a chilling fact that scientists have known for years. The world is getting warmer. After three years of steady warming, the global mean temperature rose 1.36 degree Fahrenheit in 2005 to equal the record set in 1998 as the hottest year on record.
The increase may seem slight, but scientists say the impact is not.
One of them, Karen Masters, says forests are drying up, threatening the extinction of some animal and plant species. "I don't see how extinction can be avoided" she said.
And humans are not immune. A study in the journal Nature confirms previous estimates that 150,000 more people die each year, and five million more become ill because global warming is promoting the spread of insect and water-borne diseases, especially in poor countries.
It's also causing problems in areas where few people live. In the Arctic, melting sea ice has forced polar bears to wander further, some of them to drown in the open seas.
Dr. Lara Hansen, with the World Wildlife Fund, calls it a disaster for polar bears who depend on the sea ice so they can hunt and breed.
"We know there is a minimum weight that a polar bear female has to be in order to reproduce, and polar bears are getting precariously close to that limit."
The situation has prompted at least three environmental groups to sue the U.S. government to list polar bears as an endangered species that are threatened by global warming.
Kassie Siegel, an environmental lawyer, says she is suing to, "force the Bush administration to confront global warming in a court case for the first time."
A growing number of experts blame the world's rising temperature on the use of fossil fuels and other activities that spew carbon dioxide and so called "greenhouse gases" into the atmosphere. The United States, the world's largest energy consumer, remains the holdout among developed countries. The others have signed the Kyoto protocol, an international agreement which sets limits on the emission of greenhouse gases.
Canadian Prime Minister Paul Martin chastised the Bush administration at a UN conference on climate change.
"To the reticent nations, including the United States, I'd say this: there is such a thing as a global conscience and now is the time to listen to it."
But U.S. ambassador David Wilkins defends U.S. policy, and says his country is reducing greenhouse gases and promoting cleaner energy sources. "When it comes to global consciousness, the United States is walking the walk. And when it comes to climate change, we are making significant progress, more progress than many of those who have been most critical of us."
While the debate continues, some scientists predict worldwide temperatures will rise another degree by the year 2030 and two to four degrees more by the end of this century.