September 3rd, 2009The human-driven buildup of heat-trapping greenhouse gases in the atmosphere appears to have ended a slide, many millenniums in the making, toward cooler summer temperatures in the Arctic, the authors of a new study report.
September 3rd, 2009Arctic temperatures are now higher than at any time in the last 2,000 years, research reveals. Changes to the Earth's orbit drove centuries of cooling, but temperatures rose fast in the last 100 years as human greenhouse gas emissions rose. Scientists took evidence from ice cores, tree rings and lake sediments. The 23 sites sampled were good enough to provide a decade-by-decade picture of temperatures across the region.
September 3rd, 2009A new study led by Northern Arizona University and involving the University of Colorado at Boulder indicates Arctic temperatures have reversed from a long-term cooling trend and are now the warmest they have been in at least 2,000 years, bad news for the world's coastal cities facing rising seas in the coming decades. High northern latitudes have experienced a long-term, slow cooling trend for several millennia, the result of a wobble in Earth's rotation that has been increasing the distance between the sun and Earth and decreasing Arctic summer sunshine. The research team assembled high-resolution records of climate for the past 2,000 years and found that the cooling trend reversed in the 20th century.
August 26th, 2009An international team of researchers, including scientists from the University of Colorado, drilled 5,767 feet down into the Greenland ice sheet this summer, setting a record for the length of ice core recovered in a single season. Even so, scientists will have to drill another 2,600 feet next summer to hit bedrock -- and to find the ice that Jim White, a researcher at CU's Institute for Arctic and Alpine Research, has been seeking.
August 26th, 2009A new international research effort on the Greenland ice sheet with the University of Colorado at Boulder as the lead U.S. institution set a record for single-season deep ice-core drilling this summer, recovering more than a mile of ice core that is expected to help scientists better assess the risks of abrupt climate change in the future. The project, known as the North Greenland Eemian Ice Drilling, or NEEM, is being undertaken by 14 nations and is led by the University of Copenhagen. The goal is to retrieve ice from the last interglacial episode known as the Eemian Period that ended about 120,000 years ago. The period was warmer than today, with less ice in Greenland and 15-foot higher sea levels than present -- conditions similar to those Earth faces as it warms in the coming century and beyond, said CU-Boulder Professor Jim White, who is leading the U.S. research contingent.
June 27th, 2009Summer fire seasons in the great forests of the West have always hinged on elements of chance: a heat wave in August, a random lightning strike, a passing storm front that whips a small fire into an inferno or dampens it with cooling rain. But tiny bark beetles, munching and killing pine trees by the millions from Colorado to Canada, are now increasingly adding their own new dynamic. As the height of summer fire season approaches, more than seven million acres of forest in the United States have been declared all but dead, throwing a swath of land bigger than Massachusetts into a kind of fire-cycle purgatory that forestry officials admit they do not yet have a good handle on for fire prediction or assessment.