Last year topped off a nine-year streak of global warming "unprecedented in the historical record" and largely driven by burning fossil fuels, the NCDC reported Tuesday. According to the report, average U.S. temperatures in 2006 were 2.2 degrees Fahrenheit higher than the average temperature across the country for the 20th century.
Last month -- which brought early blossoming of daffodils and cherry trees in the normally icy eastern states -- was the fourth-warmest December on record, while average temperatures for all 48 mainland states were above average or well above average.
New Jersey experienced its hottest temperatures ever on record, while Boston saw temperatures of 8 degrees above average and Minneapolis-St. Paul suffered temperatures 17 degrees higher than normal during December.
"No one should be surprised that 2006 is the hottest year on record for the U.S.," said climate scientist Brenda Ekwurzel of public interest group the Union of Concerned Scientists. "When you look at temperatures across the globe, every single year since 1993 has been in the top 20 warmest years on record."
The warming is caused mostly by excess burning of fossil fuels, which release carbon dioxide into the atmosphere. Climate scientists warn that the atmosphere has more carbon dioxide now than it has in the past 650,000 years, which is creating a blanket of the gas that traps heat on Earth. To make matters worse, the National Oceanic & Atmospheric Administration (NOAA) says an El Nino weather pattern in the Pacific near the equator has prevented icy Arctic air from moving south and east across the United States.
The Bush administration has rejected proposals in recent years to place limits on carbon dioxide emissions or adopt a system of carbon taxes to help curb the United States' sizeable contribution to greenhouse gas emissions.
NOAA chief of climate monitoring Jay Lawrimore said he believes global warming could be seriously slowed or even solved with the development of new, clean technologies for industrial and vehicular use.
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