Posted on October 25, 2013 by Bob Berwyn
‘The warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere …’
Baffin Island‘s ice caps are melting fast under an unprecedented regime of global warming, according to a new CU-Boulder study: Photo courtesy NASA.
By Summit Voice
FRISCO — After radiocarbon dating samples of moss at the edge of melting ice caps on Baffin Island, scientists said there’s little doubt that current warming in the Arctic is unprecedented, even on a geological time scale.
Average summer temperatures in the Eastern Canadian Arctic during the last 100 years are higher than during any century in the past 44,000 years and perhaps as long ago as 120,000 years, according to a University of Colorado Boulder study.
“The key piece here is just how unprecedented the warming of Arctic Canada is,” said CU-Boulder geologist Gifford Miller, also a fellow at CU-Boulder’s Institute of Arctic and Alpine Research. “This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere.” Continue reading
Filed under: climate and weather, Environment, global warming, Greenland | Tagged: Arctic, Baffin Island, climate change, global warming, greenland, Little Ice Age | 1 Comment »
Posted on September 3, 2013 by Bob Berwyn
Study shows pollution melted glaciers even as temperatures cooled
Atmospheric pollution in the form of soot from fossil fuel combustion, apparently caused a rapid retreat of Alpine glacers even as regional temperatures cooled at the start of the Industrial age. Photo courtesy NASA Earth Observatory.
By Summit Voice
FRISCO — Matching climate records with ice core samples, scientists say the rapid retreat of Alpine Glaciers in Europe at the end of the Little Ice Age was probably linked with the sudden accumulation of soot particles associated with the beginning of the industrial Age.
Soot from industrial sources and even from wildfires has recently been implicated in the darkening of the Greenland ice sheet, leading to increased surface melt.
The new study helps resolve what had been a puzzle, as the sudden glacier decline coincided with a period of cooling regional temperatures. Between 1860 and 1930, temperatures in Europe cooled by nearly two degrees, yet at the same time, any large valley glaciers retreated by an average of about 0.6 miles (1kilometer).
“Something was missing from the equation,” said lead author Tom Painter, a snow and ice scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. The study was published Sept. 2 in the Proceedings of the National Academy of Sciences. Continue reading
Filed under: climate and weather, global warming, snow | Tagged: alpine glaciers, climate, Little Ice Age, pollution, soot, The Alps | Leave a comment »
Posted on April 23, 2013 by Bob Berwyn
Late 20th century temperature spike reversed long cooling trend
New study finds that Europe’s 2003 heatwave brought the hottest temperatures in 2000 years.
By Summit Voice
SUMMIT COUNTY — Heat-trapping greenhouse gases have driven global temperatures higher than at any other time during the past 1,400 years, according to a new study covering all seven continents. The big spike between 1971 and 2000 reversed a natural cooling trend that had lasted several hundred years, according to climate data from tree rings, pollen, cave formations, ice cores, lake and ocean sediments, and historical records from around the world.
“This paper tells us what we already knew, except in a better, more comprehensive fashion,” said study co-author Edward Cook, a tree-ring scientist at Lamont-Doherty Earth Observatory who led the Asia reconstruction. Continue reading
Filed under: climate and weather, global warming | Tagged: 2003 European heat wave, climate change, global warming, greenhouse gases, Lamont–Doherty Earth Observatory, Little Ice Age, Medieval Warm Period, Nature Geoscience, University of Bern | Leave a comment »
Posted on January 23, 2013 by Bob Berwyn
New study tracks rapidly accelerating rate of ice decline since 1950s
The Perito Moreno Glacier is one of the largest in Patagonia at 30 kilometers long. The glacier descends from the Southern Patagonian Icefield (image top)—2100 meters elevation (6825 feet) in the Andes Mountains—down into the water and warmer altitudes of Lago Argentino at 180 meters above sea level. Satellite image courtesy NASA Earth Observatory.
By Summit Voice
SUMMIT COUNTY — Glaciers in large parts of the Andes have shrunk on average by 30 to 50 percent since the 1970s, and the unprecedented retreat could soon begin to affect water supplies for Andean communities.
Temperatures in the region have warmed by more than 1 degree Fahrenheit in the past few decades, said Antoine Rabatel, a researcher at the Laboratory for Glaciology and Environmental Geophysics in Grenoble, France, and lead author of a recent study on the glaciers in the region.
Globally, glaciers have been retreating at a moderate pace as the planet warmed after the peak of the Little Ice Age, a cold period lasting from the 16th to the mid-19th century. Over the past few decades, however, the rate of melting has increased steeply in the tropical Andes, at a pace not seen for at least the last 300 years. Continue reading
Filed under: climate and weather, Environment, global warming | Tagged: Andes, climate change, global warming, Intergovernmental Panel on Climate Change, Little Ice Age, tropical glaciers, water | Leave a comment »
Posted on October 19, 2012 by Bob Berwyn
Study in Alpine lakes traces 1,600-year of history climate change
Sediments in Austria’s Mondsee show more evidence of flooding during transitions to cooler climate phases.
By Summit Voice
SUMMIT COUNTY — While many recent research projects have highlighted the potential for more extreme weather as the planet warms up, a new study from the GFZ German Research Centre for Geosciences indicates that parts of the Alps saw more extreme flooding during periods of transition to cooler climatic conditions.
By studying sediment layers in the Mondsee, an Alpine lake near Salzburg, Austria, the researchers found evidence of flooding during the time of the Great Migration and the Early Middle Ages (AD 450-750), as well as the transition to the Little Ice Age (AD 1140-1520). In contrast, there was less flooding during the medieval warm phase (AD 1000-1140) and the coldest period of the Little Ice Age (AD 1600-1700). Continue reading
Filed under: climate and weather, global warming | Tagged: Alps, climate change, extreme weather, flooding, Great Migration, Little Ice Age, Mondsee | Leave a comment »
Posted on October 1, 2012 by Bob Berwyn
Paleo-climate data suggests region should be cooling, but greenhouse gas forcing has overpowered nature pattern
New research shows that the Arctic reversed a long-term cooling trend and began warming rapidly in recent decades. The blue line shows estimates of Arctic temperatures over the last 2,000 years, based on proxy records from lake sediments, ice cores and tree rings. The green line shows the long-term cooling trend. The red line shows the recent warming based on actual observations. Courtesy Science, modified by UCAR.
By Summit Voice
SUMMIT COUNTY — Without ever-increasing concentrations of heat-trapping greenhouse gases in the atmosphere, the Arctic would gradually be cooling instead of experiencing the rapid warming that’s been documented in the past few decades.
The long-term cooling trend, documented back to at least 2,000 years ago, is related to wobbles in the Earth’s orbit that have reduced the intensity of sunlight reaching the Arctic in summertime, when Earth is farther from the Sun, according to a recent study led by scientists from Northern Arizona University and the National Center for Atmospheric Research.
But in the middle of the 20th century, the gradual cooling ended abruptly, replaced by a sharp increase in Arctic temperatures — even though orbital cycles would suggest a continued cooling trend. The research, based on geologic records and computer models, strongly suggests that the heat-trapping effects of greenhouse gases are overpowering natural climate cycles. Continue reading
Filed under: Arctic, climate and weather, Environment, global warming | Tagged: Arctic, Arctic temperature increases, climate, global warming, Little Ice Age, National Center for Atmospheric Research, Northern Arizona University | Leave a comment »
Posted on September 16, 2012 by Bob Berwyn
Arctic foxes. Photo courtesy Yvonne Cox.
Study shows impacts to Arcit fox populations
By Summit Voice
FRISCO — It’s very likely that human-caused global warming will disrupt the natural cycles of glaciation that have prevailed in recent millennia, and that could spell trouble for species that have relied on bridges of sea ice to maintain genetic diversity.
That includes Arctic foxes that were able to colonize Iceland during the Little Ice, according to research by scientists at the UK’s Durham University, who said that Arctic foxes were able to migrate to Iceland from Russia, North America and Greenland when such a bridge formed, between 200 and 500 years ago.
Iceland’s population of about 10,000 arctic foxes is not at risk, the researchers said, but explained that increasing isolation from the rest of the Arctic, caused by warmer temperatures and a lack of sea ice, could further differentiate the island’s population from their mainland relatives. Continue reading
Filed under: biodiversity, climate and weather, Environment, global warming | Tagged: Arctic, Arctic fox, climate, global warming, Iceland, Little Ice Age, Natural Environment Research Council, Sea ice | Leave a comment »