Climate and Global Change Notes 28-1 Climate & Global Change Ice and Sea-Level Rise Changes Melting Expansion Science Concepts The Earth System (Kump, Kastin & Crane) Chap. 15 (pp ) Chap. 16 (pp )

Climate and Global Change Notes 28-2 Sea-Level Rise Causes of Sea-Level ChangeThermal expansionAddition of water, i.e., from melting glaciersChanges in salinity; fresh water is less dense than salt water and thus takes up slightly more space than an equal mass of salt waterGraph of data from satellites and floats (mechanical devices drifting in the ocean), show that sea level rose, on average, 3 mm (0.1 inches) per year between 1993 and 2005Researchers attributed about half of this increase to melting ice and half to thermal expansion NewImages/images.php3?img_id=17300 Change in mean sea level (mm) Trend 60-Day Average

Climate and Global Change Notes 28-3 Sea-Level Rise Causes of Sea-Level Change Intergovernmental Panel on Climate Change, Climate Change 2001; Synthesis Report, p. 67 Terrestrial water storage, extraction of groundwater, building of reservoirs, changes in runoff and seepage into aquifers Subsidence in river delta region, land movements and techtonic movements Surface and deep ocean circulation changes and storm surges Expansion of water caused by warming Exchange of the water stored on land by glaciers and ice sheets with ocean water

Climate and Global Change Notes 28-4 ExplanationSea-level could rise 1-4 ft during the next 100 y due to global warming The mechanism underlying is simple; -As ocean waters heat, they expand -Water locked up in small landed glaciers melt The Greenland and West Antarctic ice sheets each contain enough water to raise sea level about 22 ft, while East Antarctica has enough ice to raise sea level over 190 ft. Sea-Level Rise

Climate and Global Change Notes 28-5 Changes in Glacial and Sea Ice Glaciers IKONOS satellite image Bear Glacier along the Gulf of Alaska on 8/8/05 -IKONOS comes from the Greek word for "image" -IKONOS is a commercial multispectral Earth observation satellite that collects imagery at 1- and 4-m resolution Note -Small icebergs floating in lake -Crevasse region -Dark gray “racing stripes” are dirt and debris from rocks glacier passes -Bright blue-green color of small lake result of “glacial flour” - highly reflective fine sediment ground off rocks by the ice and carried down slope NewImages/images.php3?img_id=17453

Climate and Global Change Notes 28-6 Changes in Glacial and Sea Ice Glaciers Around the World - Montana & Washington “More than 110 glaciers have disappeared from Montana’s Glacier National Park over the past 150 years, and researchers estimate that the park’s remaining 37 glaciers may be gone in another 25 years.” -Example to right: Sperry Glacier retreated m/y from ; then retreated at 11 m/y to about 5 m /y from ; from retreated from 3-5 m/y South Cascade Glacier in the Washington Cascade Mountains (below) retreat from 1928, 1979, and research/glacier_retreat.htm nasa.gov/ Study/GLIMS/

Climate and Global Change Notes 28-7 Glaciers Around the World - Africa “Half a world away on the African equator, Hemingway’s snows of Kilimanjaro are steadily melting and could completely disappear in the next 20 years.” Observation - Ice on Africa's highest mountain shrank by 80% in the past century. The snow cap formed some 11,000 years ago. Landsat captured these images of Kilimanjaro 2/17/93 (top) and 2/21/00 (bottom). Changes in Glacial and Sea Ice research/news/ / Study/GLIMS/

Climate and Global Change Notes 28-8 Changes in Glacial and Sea Ice Glaciers Around the World - Alps “And in the Alps, glaciers are retreating and disappearing every year ….” Composite ASTER image of Gangotri Glacier (Himalayas) terminus -Contour lines are approximate Image by Jesse Allen, Earth Observatory; Based on data from the ASTER Science Team; Glacier retreat boundaries from the Land Processes Distributed Active Archive Center Observation - Retreating glaciers may cause some earthquakes. Study of glaciers in several parts of the world suggests that the number of earthquakes have increased as large glaciers have melted. Bull. Amer. Meteor. Soc., 2004, p.1645

Climate and Global Change Notes 28-9 Changes in Glacial and Sea Ice Glaciers Around the World - South American Glaciers South America’s Patagonian ice fields and glaciers located in the far southern Andes mountains in Argentina Upsala Glacier -Third largest glacier of the Southern Patagonian Ice Field -Estimated area of over 800 square kilometers NewImages/images.php3?img_id=16441 Yellow line Jan 2001 Yellow line Jan 2001 Jan 2004 Jan 2001

Climate and Global Change Notes Changes in Glacial and Sea Ice Glaciers Around the World - South American Glaciers (Con’t) Upsala Glacier (Con’t) -Glacial frontal margins >R indicates a bare-rock ridge [extent shown by dark grey] >ch indicates a water channel >i indicates an island [shown by light grey] chile-arg/wet/historic.html 4 km

Climate and Global Change Notes Glaciers Around the World - Greenland Ice Sheet Airborne laser used to survey the altitude of the ice sheet's surface 1993 and and 1999 Produced difference map Ice sheet lost at least 51 cubic kilometers of volume during that five year period Changes in Glacial and Sea Ice

Climate and Global Change Notes Changes in Glacial and Sea Ice Glaciers Around the World - Jakobshavn Isbrae Glacier in Greenland Fastest moving glacier in the world In recent years, it has gotten even faster Starting in late 2000, following a period of slowing down in the mid 1990s, the glacier accelerated and its speed nearly doubled Each year glacier’s front edge retreated farther inland, and the colored lines on the image above mark the location of the terminus from 2001 through NewImages/images.php3?img_id=16760

Climate and Global Change Notes Changes in Glacial and Sea Ice Sea Ice Around the World - Antarctic Temperature Trend Strongest cooling at the South Pole, strongest warming along the Antarctic Peninsula Bright red spots or streaks along edge of continent show where icebergs calved or ice shelves disintegrated, meaning satellite began seeing warmer ocean water One possible cause involves ozone in the stratosphere that absorbs UV radiation, absorbing this energy warms the stratosphere. Loss of UV-absorbing ozone may have cooled the stratosphere and strengthened the polar vortex around the South Pole ewImages/images.php3?img_id=17257

Climate and Global Change Notes Changes in Glacial and Sea Ice Sea Ice Around the World - Antarctica Image from Synthetic Aperture Radar (SAR) on the Canadian RADARSAT satellite. SAR has 100 m resolution that can sense Earth's surface in darkness or through clouds 10/13/98 ice more than 90 miles long and almost 30 miles wide broke away or “calved” from Ronne Ice Shelf in Antarctica y2000/ast27dec_1.htm

Climate and Global Change Notes Changes in Glacial and Sea Ice Sea Ice Around the World - Antarctica (Con’t) Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Earth Observing System (EOS) Terra satellite Larsen B ice shelf in Antarctica disintegrated in 35-day period Shattered ice formed a "plume" of thousands of icebergs now adrift in the Weddell Sea

Climate and Global Change Notes Changes in Glacial and Sea Ice Sea Ice Around the World - Antarctica (Con’t) Retreat of the ice shelves on the Antarctic Peninsula RADARSAT 100 km

Climate and Global Change Notes Changes in Glacial and Sea Ice Sea Ice Around the World - Arctic Changes between average and average

Climate and Global Change Notes Ocean Currents Sea Ice Around th e World - Arctic (Con’t) 2007 sets record Arctic sea ice melt Sept. 16, 2007, sea ice extent was 4.13 million km 2 (1.59 million miles 2 ) 38% below average and 24% below 2005 record 2007 brought an ice-free opening though Northwest Passage for several weeks Alaska Canada

Climate and Global Change Notes Ocean Currents Sea Ice Around the World - Arctic (Con’t) Graph of sea ice melt shows the 5-day mean sea ice extent for June through Sept. Sea ice acts as the Earth’s built-in air conditioner - its light color reflects most sunlight In contrast, dark ocean water absorbs most of sunlight As sea ice continues melting, increased exposure of ocean water changes Earth’s; thus, contributing to further warming thereby leading to continued sea ice melt and reinforcing the melting cycle As summer melt continues to increase, wintertime recovery becomes more difficult to achieve NewImages/images.php3?img_id=17782

Climate and Global Change Notes Ocean Currents Sea Ice Around the World - Arctic (Con’t) July Arctic perennial sea ice has been decreasing at a rate of 6% per decade since 1979 Images show the minimum sea ice concentration in 1979 and Data were collected by the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSMI). Credit: NASA /1023esuice.html ArcticReflector/arctic_reflector2.html

Climate and Global Change Notes FactsSea ice also thinned by about 40% in recent decades, from an average of 10 ft in the period to about 6 ft in the period On average, current thinning is estimated at about 4 in / yr.Since 1993, the Greenland Ice Sheet - the Arctic’s largest - has thinned by more than a yard a year on its southern and eastern edges.Alaskan permafrost is thawing across the state. Near Barrow, permafrost was 8 to 10 in thinner in than it was between 1964 and Woodard, C., 2000: The great melt: Is it normal, or the result of global warming. The Chronicle of Higher Education, July 14, XLVI, No. 45, A20-A21. Changes in Glacial and Sea Ice