NASA researchers are presenting a wide range of science results at the 2008 fall meeting of the American Geophysical Union. The meeting, which opens Monday and continues through Friday, Dec. 19, at the Moscone Convention Center, features more than 15,000 talks and poster presentations about the latest in Earth and planetary sciences and heliophysics.
Below are summaries of presentations by NASA researchers and their colleagues who use NASA research capabilities.
Insect Damage To Forests Measured By New Satellite-Based Method
Evergreen forests in North America have fallen prey to the worst insect infestation in recorded history. The evidence is particularly evident in British Columbia, where growing insect populations have destroyed millions of acres of pine trees in the last few years. Using NASA satellites, Jon Ranson and Paul Montesano of NASA's Goddard Space Flight Center developed a new detection technique that may soon provide loggers and forestry officials a means to monitor and measure the extent of damage.
Short-Lived Pollutants Have Large Arctic Impact
New observations and computer models show that short-lived pollutants including heat-absorbing soot and low-altitude ozone, contribute significantly to the warming trends observed recently in the Arctic. Drew Shindell of NASA's Goddard Institute for Space Studies compares the effect of these pollutants on the vulnerable northern environment with the impact of long-lived greenhouse gases such as carbon dioxide.
Studying The Archaeology And Climate Of The "Green" Sahara
NASA scientists are using space radar data, together with a variety of global climate records, to assess how climate change has affected the historical human occupation of Africa's Sahara. About 10,500 years ago, abrupt climate change turned the dry Sahara into a green savanna occupied by humans. Scientists from NASA's Jet Propulsion Laboratory and their colleagues explore the relationships between the human occupation of the Sahara and changes in solar irradiance and atmospheric-ocean circulation patterns.
NASA Observes Changes In Amazon From Tropical Deforestation
Christopher Potter of NASA's Ames Research Center and his colleagues will describe how Ames scientists were able to predict the effects of deforestation and burning on vegetation in the Amazon. Using satellite observations of monthly vegetation cover in the Brazilian Amazon from 2000 to 2004, scientists created a detailed map of aboveground biomass carbon pools, such as tropical forests. NASA scientists were able to predict losses of greenhouse gases from forests that were cut and burned each year across the region. Researchers found the total annual carbon balance of the Amazon region is three to four times higher than previously predicted.
Pollution "Weekend Effect" Seen On U.S. Southeast Lightning
The number of summertime lightning strikes in the Southeastern United States peaks during the middle of the week and decreases on weekends because of fluctuations in air pollution, according to Thomas Bell of NASA's Goddard Space Flight Center. The finding, based on analysis of lightning strike rates detected by ground-based instruments, correlates with other recently detected cycles of storminess and rainfall, which also peak midweek because of a rise in the abundance of airborne pollution from human activity. The new observations show that the trend is not confined to urban areas, which poses new questions about how pollution, cities and weather interact
Evidence For Spring Deposits And Mud Volcanoes On Mars
Scientists from NASA's Johnson Space Center and their colleagues report evidence for spring deposits in Mars' Vernal Crater in the Arabia Terra region. The Vernal springs may be part of a larger complex of spring deposits, suggesting that fluid flow in this region was relatively extensive. The researchers also mapped more than 20 pitted domes in an area of Acidalia Planitia. While a range of origins has been suggested for these domes, the researchers believe that they are similar to mud volcanoes on Earth. Together, these features are changing our understanding of the hydrologic history of Mars.
Not All Urban Heat Islands Are Equal
Scientists have struggled to define the boundaries of urban heat islands, metropolitan areas that can contribute to their own local warming. Scientists using NASA satellite observations have made the first global comparison of the heat-island effect. Marc Imhoff, Ping Zhang, and colleagues from NASA's Goddard Space Flight Center present results from a comparison of 80 such U.S. heat islands. They find that some heat islands in arid regions actually are cooler than surrounding areas. Heat islands in some non-desert regions show remarkable seasonal trends with substantially more heating in summer than in winter, suggesting that the amount of energy consumed for air conditioning will increase as cities expand.
Fire Severity Linked To Climate Change Impact Of Forest Fires
NASA researchers and their colleagues at the Russian Academy of Science, using current climate change scenarios, predict that severe fire seasons will increase in the future. Observations in recent decades indicate climate change and increasing drought length have increased the probability and occurrence of high-intensity fires, resulting in higher carbon emissions from fuel combustion and post-fire decomposition. In recent years, fires have increased in size and severity in the boreal regions of Siberia. Amber Soja of NASA's Langley Research Center observed that above-ground carbon in dead biomass tends to increase after fires, depending on the severity of the fire.
New Theory Of Origin Of Terra Meridiani Sediments On Red Planet
Paul Niles at NASA's Johnson Space Center argues that the sedimentary deposits discovered by NASA's Opportunity rover on Mars at Meridiani Planum are best explained by wind-driven reworking of residue from a large ice and dust deposit. Niles estimates that the ice deposit was located near Terra Meridiani and incorporated large amounts of dust, sand and sulfur dioxide aerosols produced by impacts and volcanism early in the planet's history. The results of this study suggest a mechanism for the movement of volatiles on Mars without invoking the theory of an early greenhouse effect on the planet.
"Peak Oil" Scenarios Reveal Implcations For Carbon Dioxide, Climate
Pushker Kharecha and James Hansen of NASA's Goddard Institute for Space Studies studied a wide range of future fossil fuel consumption scenarios. They found that the rise in carbon dioxide from burning fossil fuels can be kept below dangerous levels as long as emissions from coal are phased out globally within the next few decades. Kharecha also will discuss research that suggests target levels of carbon dioxide should be 350 parts per million, not 450 parts per million, as advocated previously.
NASA Studies Effects Of U.S. Biofuel Production On Carbon Cycle
Christopher Potter of NASA's Ames Research Center and his colleagues describe how they were able to predict the agricultural productivity of areas in the United States being converted to growing biofuel energy crops. Using computer models, scientists followed the effect of the land-use changes on carbon pools and the emission of greenhouse gasses. Their study used satellite observations of vegetation cover in Iowa and Nebraska to map above-ground and subsurface carbon pools in biofuel croplands. The researchers found that levels of organic matter in high corn-producing soils are likely to drop, having an adverse effect on the environment.