2006 was the warmest year on record in the United States and the sixth warmest worldwide, according to the National Climatic Data Center (NCDC) and the World Meteorological Organization (WMO) respectively, continuing a nine-year warming trend that scientists believe is unprecedented and may signal an acceleration of global warming.

What Caused the Exceptionally Warm Weather in 2006?

According to climate experts, the warmer-than-usual temperatures in 2006 were due to a combination of three factors:
· unusual regional weather patterns in several places that caused spring-like conditions through December and into early January;
· a cyclical El Niño effect in the Pacific Ocean; and
· the increase of carbon dioxide and other greenhouse gases in the atmosphere, which are creating an amplified greenhouse effect and contributing to global warming.

"People should be concerned about what we are doing to the climate," said Jay Lawrimore, chief of the climate monitoring branch of the National Oceanic and Atmospheric Administration (NOAA), in an interview with The Washington Post. "Burning of fossil fuels is causing an increase in greenhouse gases, and there's a broad scientific consensus that it is producing climate change."
Here are some other climate highlights for 2006:

· In the United States, average temperatures nationwide in 2006 were 2.2 degrees Fahrenheit higher than the mean temperatures nationwide for the 20th century.
· The global mean surface temperature in 2006 was 0.42 degrees Celsius above the 1961-1990 annual average of 14°C (or 57.2 degrees Fahrenheit), according to the WMO.
· 2006 was also the hottest year on record in the United Kingdom.
· December 2006 was the fourth-warmest December on record in the United States.
· Average temperatures for all 48 contiguous U.S. states were above average, or well above average for the year, and seven months in 2006 were much warmer than average.
· New Jersey recorded the hottest temperatures ever seen in that state.
· Because of the warmer U.S. temperatures from October through December, energy use for residential heating was 13.5 percent below average for those three months.

The Global Warming Debate is Over

There is no longer any serious scientific debate about whether global warming is occurring or whether greenhouse gases caused either directly or indirectly by human activities are contributing significantly to the warming trend. Where scientists still disagree is on the rate at which the global temperature is rising and how much time we have left to intervene before the planet reaches a tipping point past which there is no way to avoid or mitigate the potential devastating effects.
A single warm year is not something scientists would be concerned about, but the past nine years have all been among the hottest 25 years on record in the United States, and many have been among the warmest years globally. What has scientists worried is the trend of increasingly warm years, and a build up of greenhouse gases that is higher than at any time in the past 650,000 years (which is as far back as science has been able to take readings from ice core samples).

"No one should be surprised that 2006 is the hottest year on record for the U.S.," said Brenda Ekwurzel, a climate scientist with the Union of Concerned Scientists, in an interview with The Washington Post. "When you look at temperatures across the globe, every single year since 1993 has been in the top 20 warmest years on record."
"Realistically, we have to start fighting global warming in the next 10 years if we want to secure a safe environment for our children and grandchildren," she said.