Tuesday, October 9, 2012

Arctic melting WAY ahead of schedule

For those like me who has believed the science of climate change has been essentially settled since at least the 1980s, I sometimes get impatient that folks still feel the need to prove the point.  But because the denialists have questioned the science, the science keeps coming.  Not surprisingly, it's getting very sophisticated and mature.  11 miles (17.7 km) of core samples indeed.

Arctic Ice Melt, Sea Level Rise May Pose Imminent Threat To Island Nations, Climate Scientist Says

The Huffington Post | By James Gerken 10/05/2012

This Sept. 16, 2012, image released by NASA shows the amount of summer sea ice in the Arctic, at center in white, and the 1979 to 2000 average extent for the day shown, with the yellow line. Scientists say sea ice in the Arctic shrank to an all-time low of 1.32 million square miles on Sept. 16, smashing old records for the critical climate indicator. (AP Photo/U.S. National Snow and Ice Data Center, File)

Low-lying island nations threatened by rising sea levels this century could see the disastrous consequences of climate change far sooner than expected, according to one of the world's leading climate scientists.

In the wake of last month's discovery thatthe extent of Arctic sea ice coverage hit a record low this year, climate scientist Michael Mann told the Guardian that "Island nations that have considered the possibility of evacuation at some point, like Tuvalu, may have to be contending those sort of decisions within the matter of a decade or so."

Mann, who is the director of Pennsylvania State University's Earth System Science Center, said that current melting trends show sea ice is "declining faster than the models predict."

"The models have typically predicted that will not happen for decades but the measurements that are coming in tell us it is already happening so once again we are decades ahead of schedule," Mann told the Guardian.

This year's record melting, which occurred under more "normal" conditions than the previous record set in 2007, left Arctic sea ice at a minimum "nearly 50 percent lower than the average ... for the years 1979-2000," according to Climate Central.

Rapidly decreasing sea ice suggests that the melting of polar ice sheets may occur more rapidly than previously predicted. Mann explained to the Guardian that "we [will] really start to see sea level rises accelerate," as the Greenland and the west Antarctic ice sheets disappear. Unlike with the melting of sea ice, these ice sheets would introduce vast quantities of water into the world's oceans, making them "critical from the standpoint of sea level rise," according to Mann.

The ongoing rise in average global temperatures, which has accelerated Arctic ice melt, has been largely attributed to the burning of fossil fuels and the resultant increase in greenhouse gases like carbon dioxide in our atmosphere.

For the most vulnerable island nations, like the Maldives, Kiribati, the Torres Strait Islands and many others, rising seas will bring significant coastal erosion and saltwater contamination of limited freshwater supplies. Environmental group Oceana recently noted that nations dependent upon the sea will face food security threats as greater temperatures and atmospheric concentrations of carbon dioxide increase ocean acidity and put marine life at risk.

Despite the increasingly clear picture painted by scientific observations and climate modeling, "There's a huge gap between what is understood by the scientific community and what is known by the public," according to NASA scientist James Hansen. Recent polling suggests that as much as 35 percent of the U.S. population and 37 percent of the British public remain unconvinced of the scientific reality of climate change.  more
Ancient Climate Record Kept in 11 Miles of Ice
By OurAmazingPlanet Staff | LiveScience.com – 4 hrs ago

Inside the National Ice Core Laboratory in Denver rests more than 11 miles (18 kilometers) of ice, drilled from Earth's glaciers, which are shedding new light on the dimly understood history of the planet's climate.

These ice cores, taken from both Antarctica and the Arctic, provide a unique glimpse into the past. Scientists take pieces of the ice to perform a wide variety of experiments.

Some scientists study the bubbles trapped within the cores — each a tiny pocket of air enclosed at the time the ice formed, essentially frozen in time. Testing that air for various chemicals can tell scientists a lot about what the Earth's climate was like at the time the bubble formed.

Other researchers look at levels of chemicals that can reveal how much precipitation fell in any given year. The samples also contain particles of volcanic dust that speak to Earth's geologic past and its potential influence on climate. [Video: Ice Cold Science Heats Up Climate Debate]

Laboratory manager Mark Twickler likens the ice core layers to tree rings because each layer represents a year of weather, just as each tree ring represents a stage of growth. "The unique thing about polar glaciers is that each year brings another layer of snow," he said in a statement. "There are times where it snows less for a couple years, and then it snows more."

By looking at the composition of the snow, scientists can "tell what the temperatures were, how rough the oceans were around Antarctica, and even how dusty it was in Australia," Twickler said. "It's basically like looking at a weather report, year to year, going back in time."

The facility itself is kept at minus 10 degrees Fahrenheit (minus 23.3 degrees Celsius), so workers inside bundle up as if they were in Antarctica, where many of the samples were drilled, into a 70,000-year-old portion of the West Antarctic Ice Sheet. Researchers drilled down more than 2 miles (3.2 km) to retrieve the oldest pieces of ice in the sheet.

U.S. Geological Survey scientist Joan Fitzpatrick is looking at samples from the West Antarctic Ice Sheet to research how these masses of frozen water respond to changing climate. To do that, she creates thin wafers of ice from the core and then places the wafer samples under a microscope to analyze individual ice crystals.

"If the climate is warming, is the ice sheet going to get thinner overall?" she asked in a statement. "We really don't have a good handle on how the ice sheet as a whole will respond in a changing climate." But the samples at the lab allow scientists to compare recent data with more long-term information, to discover the impact of our behaviors on the climate. more

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