Presentation on theme: "The Big Melt Accelerates Jessica Ford New York Time May 19, 2014 glacial.html?_."— Presentation transcript:
The Big Melt Accelerates Jessica Ford New York Time May 19, glacial.html?_
Outline Background info on Glacier formation Where is the ice coming form How it effect the United States How are Scientist keeping track of the ice melt
Background info on Glacier formation Glaciers are, simply, rivers of ice formed from snow in regions that are frozen year-round. The snow compacts over time into granular, porous ice, which glaciologists call firn. When firn compacts even more, it becomes glacier ice, which flows, usually slowly, down mountainsides. Depending on how fast new snow accumulates at the top, or melts at the bottom, a glacier grows or shrinks in length and thickness.
Mountain Glaciers Some that are melting are the smallest glaciers in the high mountainous regions of the Andes, the Alps and the Himalayas and in Alaska. Together they make up only 1 percent of the ice on the planet and would cause sea level to rise only by one to two feet. However, melting from the mountain glaciers alone raises sea level about 0.7 millimeters a year.
Muir glacier at glacier bay national park and preserve in Alaska is among the many worldwide that are disappearing. Muir, left, as seen in august 1941, and photographed in august 2004, 63 yeas later.
Antarctica and Greenland The ice sheets of Antarctica and Greenland together possess about 100 times as much ice as all of the mountain glaciers combined, but contribute only slightly more to the sea level rise Greenland, with 10 percent of the world’s ice, has enough to raise sea level by 23 feet. In 2012, when summer Arctic temperatures were particularly warm, surface melting was observed almost everywhere on Greenland’s glaciers, even in the mountains. That had not happened for decades.
Where ice once capped the Sermeq Avangnardleq glacier, vast expanses of the Arctic Ocean are now clear.
Antarctica and Greenland Antarctica is the largest frozen mass on the planet, accounting for about 90 percent of the earth’s ice. East Antarctica, which is generally higher and colder and less likely to melt. West Antarctica, some of the ice resides in bowl-shape depressions, which are similarly vulnerable to melting. West Antarctica glacier disintegration is now confirming: In the coming centuries, more land will be covered by water and more of nature will be disrupted. Scientist say that the melt in West Antarctica is irreversible, and have discovered long, deep canyons below sea level and under the ice sheet. So even as the glaciers retreat, they will still be in contact with the encroaching warm water, and as a result, more ice will melt.
How it effect the USA While levels worldwide are expected to rise an average of two to three feet by 2100, they could surge more than six feet along the Atlantic seaboard. A 2012 study by the U.S. Geological Survey concluded that sea levels along the East Coast will rise three to four times faster than the global average over the next century. Miami, one of the nation’s most populous cities, is built atop a porous limestone foundation on the South Florida coast, making it extremely vulnerable to rising sea levels As Arctic ice continues to melt, the waters around Miami could rise up to 24 inches by 2060
Of the 50 states, Florida is the most vulnerable to rising sea levels, standing just a few feet above the current level. Miami is in an especially dangerous position because of its porous limestone foundation
Keeping Track Not to long ago, the only way to measure glaciers was to put stakes in the ice. With using surveying tools, glaciologists would mark the location and return later to see how far the ice had moved. Today satellites are used to help provided a global view NASA’s Gravity Recovery and Climate Experiment, or Grace IceSat, bounced lasers off the ice to precisely measure glaciers’ height.
Conclusion Scientists say that the melting will continue as long as the heat- trapping carbon dioxide in the atmosphere increases. Even if carbon dioxide and temperatures stabilize, the melting and shifting of glaciers will continue for decades or centuries as they adjust to the new equilibrium. And if a full melt happens it would cause the sea to rise 215 ft.
Bibliography Scientists Warn of Rising Oceans From Polar Melt By JUSTIN GILLIS and KENNETH CHANG MAY 12, say.html?action=click&contentCollection=Science&module=RelatedCoverage®ion=Marginalia&pgtype=article&_r=0 Consider Clashing Scientific and Societal Meanings of ‘Collapse’ When Reading Antarctic Ice News By ANDREW C. REVKIN May 12, :21 pm antarctic-ice- news/?action=click&contentCollection=Environment&module=RelatedCoverage®ion=Marginalia&pgtype=article How are glaciers formed?