Sea Ice & CO2 Levels

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	The Importance of Sea Ice

This simulation shows how increasing CO2 levels may affect sea ice thickness at the poles. Visualizations are shown for both a control run, where CO2 levels remain constant, and an experimental run, with CO2 levels increasing at 1 percent per year. The 50-year control run reveals no perceptible change in ice thickness. However, after 140 years of integration the increasing CO2 run obtains a quadrupling of atmospheric CO2 and shows a dramatic reduction in sea ice thickness at the North Pole. The ice thickness is depicted with a blue to white color mapping, where white represents the thickest ice.

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Animations of monthly averaged data for the southern hemisphere also clearly show a large annual cycle.

Control Run, Jul-Aug-Sep Averages, Year 170 - Year 219

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By averaging over the Northern Hemisphere Summer months (July-August-September), the seasonal influences are dimished, making the interannual changes more evident. This control run animation reveals interannual variability (consistent with observations), but there is no perceptible change in ice thickness over the 50 year period.

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In the CO2 runs, year 220 is present day and atmospheric CO2 is assumed to increase at 1% per year.

After 70 years of integration, CO2 levels have doubled from their present day levels, and there are large open water areas present within the Arctic basin during the late summer (September). By this time, the annually averaged global surface air temperature has warmed by a little over 1C. However, the warming in the Arctic is greater than 3 times this amount, and is the largest on the globe.

After 140 years of integration, CO2 levels have quadrupled from their present day levels, and the Arctic is largely ice free in the summer months. This has important implications for climate as well as effects on socio-economic conditions. Some nations, for example, are very interested in the possibility of opening shipping channels across the Arctic and exploiting this connection between the Atlantic and Pacific Oceans. Also, the disappearance of the ice pack could have a negative impact on wildlife such as seals and polar bears which use the ice pack for breeding and hunting grounds.

North Pole

Sept 220

Sept 369

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(click images to enlarge)

In the Southern Hemisphere, the sea ice does thin under the climate change scenario runs, but the changes are typically smaller than those observed in the northern hemisphere. This is likely due to changes in ocean heat uptake.

Year 220

Year 369

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(click images to enlarge)

These visualizations show the JAS averages and include a red line that depicts the maximum extent of 1 cm thick sea ice from the summer averaged control run. Interannual variability is evident again, but there is a very perceptible change in ice thickness over the 150 year period.

Year 220

Year 369

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(click images to enlarge)

• Marika Holland, CGD/NCAR
• Cecilia Bitz, U. Washington
• Bruce Briegleb, CGD/NCAR
• Elizabeth Hunke, LANL
• Bill Lipscomb, LANL
• Richard Moritz, U. Washington
• Julie Schramm, CGD/NCAR

• Fred Clare, NCAR/CISL
• John Clyne, NCAR/CISL
• Tim Scheitlin, NCAR/CISL

2003-02-01