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The Earth Observer July - August 2012 Volume 24, Issue 4 15

sheets and what we are learning about them through satellite data. Comparisons were

made between the Arctic and Antarctic sea- and land-ice changes over the last 30

years, highlighting the record-low Arctic sea ice areal extent in 2007 and the importance

of land-ice changes to sea-level rise. Prominent Arctic sea ice decreases since the

late 1970s were attributed at least in part to warming

in the Arctic region, whereas the mixed pattern

of sea ice increases and decreases in the Antarctic require

more complicated explanations, including possible

circulation changes.

Ralph Kahn’s [GSFC] presentation, titled, How

the Sun and a Changing Atmosphere Affect Climate,

focused on how climate is controlled by changes

in various radiative forcing components. The major

components are greenhouse gases, such as CO 2

and water vapor; airborne particles, such as wildfire

smoke, desert dust, volcanic ash, and urban and industrial

pollution; the reflectivity of Earth’s surface;

and the Sun. The strongest evidence pointing to

human-caused climate changes were temperature

simulations covering the last 90 years, reported by

the Intergovernmental Panel on Climate Change

(IPCC). They showed the differences between climate model results that included

and excluded anthropogenic forcing (primarily measured CO 2

increases). Those simulations

that included the increased anthropogenic forcing matched the observed

temperatures much more closely.

[Left to right] Gary Maxwell,

Mandy Warner, Compton

Tucker, Claire Parkinson, and

Ralph Kahn during the Q&A

period at the community

event. Image credit: NASA

feature articles

Compton Tucker [GSFC], whose presentation was titled, The Carbon Cycle: Observations

of Sources and Sinks, began by reviewing the carbon cycle and then discussed

the impact of climate change on the biosphere. Using satellite data, he showed that as

the Arctic warmed, it became greener. In contrast, satellite data showed that tropical

glacier mass decreased significantly (27% in 20 years), and was correlated to the increased

temperatures.

The following Q&A period (with questions submitted by the audience during the

break) was handled by a panel consisting of the three NASA scientists and three guest

experts representing the science policy community: Gray Maxwell [U.S. Senator Ben

Cardin’s Floor Manager], Mandy Warner [Environmental Defense Fund (EDF)—

Climate and Air Quality Analyst], and Clark Weaver [Goddard Earth Sciences and

Technology Center (GEST), representing the American Geophysical Union (AGU)].

Before the Q&A period, each of the guest panelists commented on the preceding

GSFC lectures and then described their own experience with climate change policy.

Maxwell, on behalf of Senator Cardin, initially thanked GSFC for its climate research

efforts. He went on to explain the difficulties Congress encounters when trying to

move climate legislation forward because of strong political positions taken by Congress

members, regardless of scientific results and predictions.

Warner explained the advocacy role of the EDF in working with Congress and government

agencies such as the Environmental Protection Agency (EPA) and the U.S.

Department of Energy. Progress has been limited because of increased partisanship at

the national level. However, Warner assured the attendees that there is progress at state

and local levels for reducing emissions, as exemplified by activities in California. She

also noted the success in implementating the administration’s new Corporate Average

Fuel Efficiency (CAFE) automobile gas mileage standards and the pending EPA restrictions

on power plant emissions.

Weaver, representing the AGU, gave an account of his visit to Capitol Hill to discuss

climate change with members of Congress and their staffs. He pointed out that their

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