NASA finds long-term increase in rainfall in tropics
NASA scientists have detected the first signs that tropical rainfall is on the rise with the longest and most complete data record available.
Using a 27-year-long global record of rainfall assembled by the international scientific community from satellite and ground-based instruments, the scientists found that the rainiest years in the tropics between 1979 and 2005 were mainly since 2001. The rainiest year was 2005, followed by 2004, 1998, 2003 and 2002, respectively.
"A warming climate is the most plausible cause of this observed trend in tropical rainfall," says co-author Robert F. Adler, senior scientist at Goddard's Laboratory for Atmospheres. Adler and Gu are now working on a detailed study of the relationship between surface temperatures and rainfall patterns to further investigate the possible link. The study [*abstract] appears in the Aug. 1, 2007, issue of the American Meteorological Society's Journal of Climate.
Obtaining a global view of our planet's rainfall patterns is a challenging work-in-progress:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: rain :: precipitation :: climate change :: water cycle :: tropics ::
Only since the satellite era have regular estimates of rainfall over oceans been available to supplement the long-term but land-limited record from rain gauges. Just recently have the many land- and space-based data been merged into a single global record endorsed by the international scientific community: the Global Precipitation Climatology Project, sponsored by the World Climate Research Program. Adler's research group at NASA produces the project's monthly rainfall updates, which are available to scientists worldwide.
Using this global record, Gu, Adler and their colleagues identified a small upward trend in overall tropical rainfall since 1979, but their confidence was not high that this was an actual long-term trend rather than natural year-to-year variability. So they took another look at the record and removed the effects of the two major natural phenomena that change rainfall: the El Niño Southern Oscillation and large volcanic eruptions.
El Niño is a cyclical warming of the ocean waters in the central and eastern tropical Pacific that generally occurs every three to seven years and alters weather patterns worldwide. Volcanoes that loft debris into the upper troposphere and stratosphere create globe-circling bands of aerosol particles that slow the formation of precipitation by increasing the number of small cloud drops and temporarily shielding the planet from sunlight, which lowers surface temperatures and evaporation that fuels rainfall. Two such eruptions - El Chicon in Mexico and Mount Pinatubo in the Philippines - occurred during the 27-year period.
The scientists found that during El Niño years, total tropical rainfall did not change significantly but more rain fell over oceans than usual. The two major volcanoes both reduced overall tropical rainfall by about 5 percent during the two years following each eruption. With these effects removed from the rainfall record, the long-term trend appears more clearly in both the rainfall data over land and over the ocean.
According to Adler, evidence for the rainfall trend is holding as more data come in. The latest numbers for 2006 show another record-high year for tropical rainfall, tying 2005 as the rainiest year during the period.
"The next step toward firmly establishing this initial indication of a long-term tropical rainfall trend is to continue to lengthen and improve our data record," says Adler, who is project scientist of the Tropical Rainfall Measuring Mission (TRMM), a joint mission between NASA and the Japan Aerospace Exploration Agency. The three primary instruments on TRMM are currently providing the most detailed view of rainfall ever provided from space. Adler's group has been incorporating TRMM rainfall data since 1997 into the global rainfall record.
NASA plans to extend TRMM's success of monitoring rainfall over the tropics to the entire globe with the Global Precipitation Measurement mission, scheduled for launch in 2013. This international project will provide measurements of both rain and snow around the world with instruments on a constellation of spacecraft flying in different orbits.
Image (click to enlarge): 6-year TRMM climatology, precipitation January 1998-December 2003. Credit: Nasa TRMM.
References:
Gu, G., R.F. Adler, G.J. Huffman, and S. Curtis, 2007: "Tropical Rainfall Variability on Interannual-to-Interdecadal and Longer Time Scales Derived from the GPCP Monthly Product" [*abstract], Journal of Climate, 20, 4033–4046.
NASA Goddard Space Flight Center: Tropical Rainfall Measuring Mission website.
The Global Precipitation Climatology Project (GPCP)
Article continues
Using a 27-year-long global record of rainfall assembled by the international scientific community from satellite and ground-based instruments, the scientists found that the rainiest years in the tropics between 1979 and 2005 were mainly since 2001. The rainiest year was 2005, followed by 2004, 1998, 2003 and 2002, respectively.
When we look at the whole planet over almost three decades, the total amount of rain falling has changed very little. But in the tropics, where nearly two-thirds of all rain falls, there has been an increase of 5 percent. - Guojun Gu, research scientist at Goddard Space Flight Center, lead authorThe rainfall increase was concentrated over tropical oceans, with a slight decline over land. Climate scientists predict that a warming trend in Earth's atmosphere and surface temperatures would produce an accelerated recycling of water between land, sea and air. Warmer temperatures increase the evaporation of water from the ocean and land and allow air to hold more moisture. Eventually, clouds form that produce rain and snow.
"A warming climate is the most plausible cause of this observed trend in tropical rainfall," says co-author Robert F. Adler, senior scientist at Goddard's Laboratory for Atmospheres. Adler and Gu are now working on a detailed study of the relationship between surface temperatures and rainfall patterns to further investigate the possible link. The study [*abstract] appears in the Aug. 1, 2007, issue of the American Meteorological Society's Journal of Climate.
Obtaining a global view of our planet's rainfall patterns is a challenging work-in-progress:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: rain :: precipitation :: climate change :: water cycle :: tropics ::
Only since the satellite era have regular estimates of rainfall over oceans been available to supplement the long-term but land-limited record from rain gauges. Just recently have the many land- and space-based data been merged into a single global record endorsed by the international scientific community: the Global Precipitation Climatology Project, sponsored by the World Climate Research Program. Adler's research group at NASA produces the project's monthly rainfall updates, which are available to scientists worldwide.
Using this global record, Gu, Adler and their colleagues identified a small upward trend in overall tropical rainfall since 1979, but their confidence was not high that this was an actual long-term trend rather than natural year-to-year variability. So they took another look at the record and removed the effects of the two major natural phenomena that change rainfall: the El Niño Southern Oscillation and large volcanic eruptions.
El Niño is a cyclical warming of the ocean waters in the central and eastern tropical Pacific that generally occurs every three to seven years and alters weather patterns worldwide. Volcanoes that loft debris into the upper troposphere and stratosphere create globe-circling bands of aerosol particles that slow the formation of precipitation by increasing the number of small cloud drops and temporarily shielding the planet from sunlight, which lowers surface temperatures and evaporation that fuels rainfall. Two such eruptions - El Chicon in Mexico and Mount Pinatubo in the Philippines - occurred during the 27-year period.
The scientists found that during El Niño years, total tropical rainfall did not change significantly but more rain fell over oceans than usual. The two major volcanoes both reduced overall tropical rainfall by about 5 percent during the two years following each eruption. With these effects removed from the rainfall record, the long-term trend appears more clearly in both the rainfall data over land and over the ocean.
According to Adler, evidence for the rainfall trend is holding as more data come in. The latest numbers for 2006 show another record-high year for tropical rainfall, tying 2005 as the rainiest year during the period.
"The next step toward firmly establishing this initial indication of a long-term tropical rainfall trend is to continue to lengthen and improve our data record," says Adler, who is project scientist of the Tropical Rainfall Measuring Mission (TRMM), a joint mission between NASA and the Japan Aerospace Exploration Agency. The three primary instruments on TRMM are currently providing the most detailed view of rainfall ever provided from space. Adler's group has been incorporating TRMM rainfall data since 1997 into the global rainfall record.
NASA plans to extend TRMM's success of monitoring rainfall over the tropics to the entire globe with the Global Precipitation Measurement mission, scheduled for launch in 2013. This international project will provide measurements of both rain and snow around the world with instruments on a constellation of spacecraft flying in different orbits.
Image (click to enlarge): 6-year TRMM climatology, precipitation January 1998-December 2003. Credit: Nasa TRMM.
References:
Gu, G., R.F. Adler, G.J. Huffman, and S. Curtis, 2007: "Tropical Rainfall Variability on Interannual-to-Interdecadal and Longer Time Scales Derived from the GPCP Monthly Product" [*abstract], Journal of Climate, 20, 4033–4046.
NASA Goddard Space Flight Center: Tropical Rainfall Measuring Mission website.
The Global Precipitation Climatology Project (GPCP)
Article continues
Monday, August 27, 2007
Major breakthrough: researchers engineer sorghum that beats aluminum toxicity
The research [*abstract], to be published in the September issue of Nature Genetics, provides insights into how specialized proteins in the root tips of some cultivars of sorghum and such related species as wheat and maize can boost aluminum tolerance in crops.
Sorghum is an important crop in Africa, Central America and South Asia and is the world's fifth most important cereal crop. Scientists also see the plant as a major energy crop and have received serious funding to develop drought-tolerant sorghums for biomass production (more here, here, here and here) as well as varieties that boost both food, fodder and fuel production all at the same time (earlier post, here and especially here). The new aluminum toxicity resistant plant could make sorghum a robust crop that can drive the bioeconomy forward.
Kochian's research shows that in aluminum-tolerant sorghum varieties, special proteins in the root tip release citric acid into the soil in response to aluminum exposure. Citric acid binds aluminum ions very effectively, preventing the toxic metal from entering the roots:
energy :: sustainability :: ethanol :: biomass :: bioenergy :: biofuels :: :: agriculture :: energy crops :: sorghum :: aluminum toxicity :: soil :: developing world :: biotechnology ::
Kochian and colleagues, including the paper's first author, Jurandir Magalhaes, who received his Ph.D. from Cornell in Kochian's lab and now directs his own lab at the Embrapa Maize and Sorghum Research Center in Brazil, used genetic mapping to identify a single gene that encodes a novel membrane-transporter protein responsible for the citric acid release. The gene, they discovered, is only turned on to express the protein and transport citric acid when aluminum ions are present in the surrounding soil.
The researchers have now used the sorghum gene to engineer transgenic aluminum-tolerant Arabidopsis thaliana (a small mustard plant used in plant research because of its small genome and short life cycle) and wheat plants. Sorghum is harder to genetically transform, Kochian said.
The map-based cloning of this agronomically important gene in sorghum is helping advance this species as a model for further exploring the mechanisms of aluminum tolerance and discovering new molecular genetic solutions to improving crop yields, Kochian said.
"This research also has environmental implications for badly needed increases in food production on marginal soils in developing countries," said Kochian. "For example, if we can increase food production on existing lands, it could limit encroachment into other areas for agriculture." Alternatively, it could free up land for energy crop production.
The research is supported in part by the McKnight Foundation Collaborative Crop Research Program, the Generation Challenge Program, the National Science Foundation and the USDA-ARS.
Map: Aluminum toxicity in acidic soils limits crop production in as much as half the world's arable land, mostly in developing countries in Africa, Asia and South America. Credit: Cornell University Chronicle Online.
References:
Leon V. Kochian et. al., "A gene in the multidrug and toxic compound extrusion (MATE) family confers aluminum tolerance in sorghum", Nature Genetics, advanced online publication, 26 August 2007 | doi:10.1038/ng2074
Cornell University Chronicles Online: Cornell researchers clone aluminum-tolerance gene in sorghum, promising boost to crop yields in developing world - August 27, 2007
Biopact: ICRISAT harnesses ethanol from drought tolerant sweet sorghum - January 25, 2007
Biopact: Sun Grant Initiative funds 17 bioenergy research projects - August 20, 2007
Biopact: Joint Genome Institute announces 2008 genome sequencing targets with focus on bioenergy and carbon cycle - June 12, 2007
Biopact: ICRISAT's pro-poor biofuel projects provide livelihood and food security to landless farmers in India - August 13, 2007
Biopact: Researchers and producers optimistic about sweet sorghum as biofuel feedstock - July 27, 2007
Biopact: Mapping sorghum's genome to create robust biomass crops - June 24, 2007
Bipact: ICRISAT launches pro-poor biofuels initiative in drylands - March 15, 2007
Article continues
posted by Biopact team at 11:15 PM 1 comments links to this post