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Goddard Global Warming Warning

While NASA Administrator Michael Griffin and National Public Radio debate semantics on whether NASA is doing enough to support climate studies, the agency and Columbia University are about to release more data on global warming, supported by Goddard Space Flight Center spacecraft data.

The data involve the arctic and Antarctic, viewed here from the Galileo spacecraft (Click on picture to enlarge). The lead author of a new report on the issue is James Hansen, of NASA’s Goddard Institute for Space Studies in New York. The institute makes heavy use of data generated by spacecraft under the Goddard Space Center in Greenbelt, Md. near Washington.

Hansen’s scientific work was earlier at the center of controversy when a Bush administration political appointee in public affairs at NASA Headquarters allegedly changed NASA releases to reinforce administration policy.

The new NASA and Columbia Earth Institute data find that human-made greenhouse gases have brought the Earth's climate close to critical tipping points, with potentially dangerous consequences for the planet, NASA managers say. "If global emissions of carbon dioxide continue to rise at the rate of the past decade, this research shows that there will be disastrous effects, including increasingly rapid sea level rise, increased frequency of droughts and floods, and increased stress on wildlife and plants due to rapidly shifting climate zones," says Hansen.

From a combination of climate models, satellite data, and data from ancient polar ice, scientists conclude that the West Antarctic ice sheet, Arctic ice cover, and regions providing fresh water sources and species habitat are under threat from continued global warming, NASA says.

Hansen’s research appears in the current issue of the scientific journal Atmospheric Chemistry and Physics.

Tipping points can occur during climate change when the climate reaches a state such that strong amplifying feedbacks are activated by only moderate additional warming. This study finds that global warming of 0.6 deg C in the past 30 years has been driven mainly by increasing greenhouse gases, and only moderate additional climate forcing is likely to set in motion disintegration of the West Antarctic ice sheet and Arctic sea ice.

Amplifying feedbacks include increased absorption of sunlight as melting exposes darker surfaces and speedup of iceberg discharge as the warming ocean melts ice shelves that otherwise inhibit ice flow. Goddard and other researchers used data on earlier warm periods in Earth's history to estimate climate impacts as a function of global temperature, climate models to simulate global warming, and satellite data to verify ongoing changes.

--Craig Covault

Pentagon Gains On Next-Generation Missile Warning

After 10 years of development and billions of dollars of cost overrun, the Pentagon is beginning to gain confidence in progress on its $11 billion next-generation space-based missile warning system. Testing on the first geosynchronous Space-Based Infrared System (Sbirs) satellite at Lockheed Martin's Sunnyvale, Calif., manufacturing facility is continuing as officials there await delivery of its payload this summer. Northrop Grumman, which builds the Sbirs sensors, is also continuing tests on the GEO-1 payload at its plant in Asuza, Calif. Pictured here is the GEO-1 bus in the thermal vacuum chamber in Sunnyvale. It completed the test cycle earlier this year. Below the jump (click on "Continue reading...") is the Northrop Grumman sensor. This photo is taken from the front of the sensor, and the two lenses – one each for an infrared scanning sensor and staring sensor – are shown. For details about progress with Sbirs and new infrared imagery of a satellite boosting into orbit captured from the first Sbirs sensor in space, read the article on page 24 of the June 4 edition of Aviation Week & Space Technology.

Active Water Cycle Discovered

Using observations by NASA's Mars Odyssey orbiter, (Click on image to enlarge) scientists have discovered that water ice lies at variable depths over small-scale patches on Mars, an indication that Mars has a currently active water cycle—a major discovery.

The findings draw a much more detailed picture of underground ice on Mars than was previously available. They suggest that when NASA's next Mars mission, the Phoenix Mars Lander, starts digging to icy soil on an arctic plain in 2008, it might find the depth to the ice differs in trenches just a few feet apart.  Phoenix is completing launch processing at the Kennedy Space Center in preparation for its scheduled Aug. 3 launch.

The new results appear in the May 3, 2007, issue of the journal Nature.

"We find the top layer of soil has a huge effect on the water ice in the ground," said Joshua Bandfield, a research specialist at Arizona State University, Tempe, and author of the paper. His findings come from data sent back to Earth by the Thermal Emission Imaging System camera on Mars Odyssey. The instrument takes images in five visual bands and 10 heat-sensing (infrared) ones.

The new results were made using infrared images of sites on far-northern and far-southern Mars, where buried water ice within an arm's length of the surface was found five years ago by the Gamma Ray Spectrometer suite of instruments on Mars Odyssey.

Color coding in this map of a far-northern site on Mars indicates the change in nighttime ground-surface temperature between summer and fall. This site, like most of high-latitude Mars, has water ice mixed with soil near the surface. The ice is probably in a rock-hard frozen layer beneath a few centimeters or inches of looser, dry soil. The amount of temperature change at the surface likely corresponds to how close to the surface the icy material lies. Phoenix will land in the north polar regon at about 70 degrees north latitude.

The dense, icy layer retains heat better than the looser soil above it, so where the icy layer is closer to the surface, the surface temperature changes more slowly than where the icy layer is buried deeper. On the map, areas of the surface that cooled more slowly between summer and autumn (interpreted as having the ice closer to the surface) are coded blue and green. Areas that cooled more quickly (interpreted as having more distance to the ice) are coded red and yellow.

The depth to the top of the icy layer estimated from these observations, as little as 5 centimeters (2 inches), matches modeling of where it would be if Mars has an active cycle of water being exchanged by diffusion between atmospheric water vapor and subsurface water ice.

--Craig Covault