Sep. 4--The Arctic has not only been warming rapidly in recent decades, this warming has reversed a cooling trend that had lasted nearly 2,000 years until the turn of the century, says a new study whose authors include University of Arizona and Northern Arizona University researchers.

The study, to be published today in a leading journal, hammers home more than ever the contribution of human-induced, greenhouse-gas buildup toward warming in that region, the authors said Thursday. They said the study showed or strongly suggested that: --Temperatures in the Arctic have risen 2.2 degrees on average from 1900 until now, even though the Arctic area has been receiving less energy from the summer sun for the past 8,000 years. That's due to changes in the Earth's orbiting patterns around the sun.

--The decade 1999-2008 was the Arctic's warmest in 2,000 years.

--The period 1950-2000 was the region's warmest 50-year stretch over that same 2,000 years.

--The rapid warming of the Arctic could be contributing to the unusually dry weather that has plagued the Southwest for a decade, particularly reducing this region's winter rainfall -- because winter storms are now going farther north than they used to.

--The Arctic has warmed about 2.5 degrees faster over the past decade than it would have if the cooling that had lasted until about 1900 had continued. That's about as much as the region had cooled over the 1,900-year period ending in the year 1900.

In addition, the New York Times reported that climate experts not connected with this study said that the human-caused warming could even fend off what had been presumed an inevitable descent into a new ice age over the next several dozen millenniums. The study is being published in the journal Science.

Several scientists who were not involved with the study concurred that the extent and pace of the temperature reversal far exceeds the natural level of variability in Arctic temperatures, supporting the idea that the warmup is human-caused and potentially disruptive, the Times reported.

"Without doubt, greenhouse-gas emissions are altering the normal cooling trend on large spatial scales throughout the Arctic," said Julie Brigham-Grette, an Arctic climate specialist at the University of Massachusetts familiar with the study.