Kamis, 19 Agustus 2010

Drought Drives Decade-Long Decline in Plant Growth


Earth has done an ecological about-face: Global plant productivity that once flourished under warming temperatures and a lengthened growing season is now on the decline, struck by the stress of drought.

NASA-funded researchers Maosheng Zhao and Steven Running, of the University of Montana in Missoula, discovered the global shift during an analysis of NASA satellite data. Compared with a six-percent increase spanning two earlier decades, the recent ten-year decline is slight -- just one percent. The shift, however, could impact food security, biofuels, and the global carbon cycle.

"We see this as a bit of a surprise, and potentially significant on a policy level because previous interpretations suggested that global warming might actually help plant growth around the world," Running said.

"These results are extraordinarily significant because they show that the global net effect of climatic warming on the productivity of terrestrial vegetation need not be positive -- as was documented for the 1980’s and 1990’s," said Diane Wickland, of NASA Headquarters and manager of NASA's Terrestrial Ecology research program.

Conventional wisdom based on previous research held that land plant productivity was on the rise. A 2003 paper in Science led by then University of Montana scientist Ramakrishna Nemani (now at NASA Ames Research Center, Moffett Field, Calif.) showed that global terrestrial plant productivity increased as much as six percent between 1982 and 1999. That's because for nearly two decades, temperature, solar radiation and water availability -- influenced by climate change -- were favorable for growth.

Setting out to update that analysis, Zhao and Running expected to see similar results as global average temperatures have continued to climb. Instead, they found that the impact of regional drought overwhelmed the positive influence of a longer growing season, driving down global plant productivity between 2000 and 2009. The team published their findings Aug. 20 in Science.

"This is a pretty serious warning that warmer temperatures are not going to endlessly improve plant growth," Running said.

The discovery comes from an analysis of plant productivity data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite, combined with growing season climate variables including temperature, solar radiation and water. The plant and climate data are factored into an algorithm that describes constraints on plant growth at different geographical locations.

For example, growth is generally limited in high latitudes by temperature and in deserts by water. But regional limitations can very in their degree of impact on growth throughout the growing season.

Zhao and Running's analysis showed that since 2000, high-latitude northern hemisphere ecosystems have continued to benefit from warmer temperatures and a longer growing season. But that effect was offset by warming-associated drought that limited growth in the southern hemisphere, resulting in a net global loss of land productivity.

"This past decade’s net decline in terrestrial productivity illustrates that a complex interplay between temperature, rainfall, cloudiness, and carbon dioxide, probably in combination with other factors such as nutrients and land management, will determine future patterns and trends in productivity," Wickland said.


New Computer Model Advances Climate Change Research

Simulation of Earth's climate.

 Community Earth System Model to be used in next IPCC assessment

This simulation, produced by the CCSM, provides new knowledge about Earth's climate.

Scientists can now study climate change in far more detail with powerful new computer software released by the National Center for Atmospheric Research (NCAR) in Boulder, Colo.

The Community Earth System Model will be one of the primary climate models used for the next assessment by the Intergovernmental Panel on Climate Change (IPCC).

The CESM is the latest in a series of NCAR-based global models developed over the last 30 years. The models are jointly supported by the U.S. Department of Energy (DOE) and the National Science Foundation (NSF), which is NCAR's sponsor.

Scientists and engineers at NCAR, DOE laboratories, and several universities developed the CESM.
"The Community Earth System Model is yet another step toward representing improved physics and biogeochemistry in a coupled model," says Anjuli Bamzai, program director in NSF's Division of Atmospheric and Geospace Sciences, which funds NCAR.

"As our understanding of climate-relevant processes improves, it is imperative to represent these processes in the model."

The new model's advanced capabilities will help scientists shed new light on some of the critical mysteries of global warming, including:
  • What impact will warming temperatures have on the massive ice sheets in Greenland and Antarctica?
  • How will patterns in the ocean and atmosphere affect regional climate in coming decades?
  • What will be the likely interaction of climate change and tropical cyclones, including hurricanes?
  • How will tiny airborne particles, known as aerosols, affect clouds and temperatures?
The CESM is one of about a dozen climate models worldwide that can be used to simulate the many components of Earth's climate system, including the oceans, atmosphere, sea ice, and land cover.
The CESM and its predecessors are unique among these models in that they were developed by a broad community of scientists. The model is freely available to researchers worldwide.

"With the Community Earth System Model, we can pursue scientific questions that we could not address previously," says NCAR scientist James Hurrell, chair of the scientific steering committee that developed the model.

"Thanks to its improved physics and expanded biogeochemistry, it gives us a better representation of the real world."

Climate scientists rely on computer models to better understand Earth's climate system because they cannot conduct large-scale experiments on the atmosphere itself.

Climate models, like weather models, rely on a three-dimensional mesh that reaches high into the atmosphere and into the oceans.

At regularly spaced intervals, or grid points, the models use laws of physics to compute atmospheric and environmental variables, simulating the exchanges among gases, particles, and energy across the atmosphere.
Because climate models cover far longer periods than weather models, they cannot include as much detail. Thus, climate projections appear on regional to global scales rather than local scales.

This approach enables researchers to simulate global climate over years, decades, or millennia. To verify a model's accuracy, scientists typically simulate past conditions and then compare the model results to actual observations.

The CESM builds on the Community Climate System Model, which NCAR scientists and collaborators have regularly updated since first developing it more than a decade ago.

The new model enables scientists to gain a broader picture of Earth's climate system by incorporating more influences.

Using the CESM, researchers can now simulate the interaction of marine ecosystems with greenhouse gases; the climatic influence of ozone, dust, and other atmospheric chemicals; the cycling of carbon through the atmosphere, oceans, and land surfaces; and the influence of greenhouse gases on the upper atmosphere.

In addition, an entirely new representation of atmospheric processes in CESM will allow researchers to pursue a much wider variety of applications, including studies of air quality and biogeochemical feedback mechanisms.

Scientists have begun using both the CESM and the Community Climate System Model for an ambitious set of climate experiments to be featured in the next IPCC assessment reports, scheduled for release during 2013-14.

Most of the simulations in support of that assessment are scheduled to be completed and publicly released beginning in late 2010, so that the broader research community can complete its analyses in time for inclusion in the assessment.

The new IPCC report will include information on regional climate change in coming decades.
Using the CESM, Hurrell and other scientists hope to learn more about ocean-atmosphere patterns such as the North Atlantic Oscillation and the Pacific Decadal Oscillation, which affect sea surface temperatures as well as atmospheric conditions.

Such knowledge, Hurrell says, can eventually lead to forecasts spanning several years of potential weather impacts, such as a particular region facing a high probability of drought, or another region likely facing several years of cold and wet conditions.

"Decision makers in diverse arenas need to know the extent to which the climate events they see are the product of natural variability, and hence can be expected to reverse at some point, or are the result of potentially irreversible, human-influenced climate change. CESM will be a major tool to address such questions."

Media Contacts Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
David Hosansky, NCAR (303) 497-8611 hosansky@ucar.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2010, its budget is about $6.9 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives over 45,000 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly. 

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Indonesia Butuh Peta Mikrozonasi Untuk Manajemen Bencana

Indonesia sudah melansir peta gempa Indonesia yang baru beberapa waktu lalu. Peta ini akan sangat bermanfaat dalam manajemen bencana di Indonesia terkait dengan hazard gempa tektonik.

Namun peta itu tidak akan banyak membantu mengetahui risiko akibat gempa bila tidak diikuti dengan pembuatan peta mikrozonasi pada daerah-daerah rawan gempa. Sekedar info saja, belum satupun kota-kota di Indonesia yang memiliki peta mikrozonasi.

Apa manfaat peta mikrozonasi dengan skala 200 meter? Ketua Tim Revisi Peta Gempa Indonesia Masyhur Irsyam yang juga Guru Besar FT Sipil dan Lingkungan ITB menyatakan bahwa dengan peta ini akan lebih mudah mengetahui bangunan mana yang kuat atau tidak terhadap gempa.

Ini dikarenakan bahwa setiap daerah memiliki karakter yang berbeda walaupun, bisa jadi, dalam satu provinsi yang sama. Misalnya DKI Jakarta saja, daerah utara dan selatan memiliki karakteristik tersendiri tanahnya. Bagian utara lebih tebal lapisan lunaknya sedangkan bagian selatan kebalikannya. Hal ini akan berpengaruh bila terjadi gempa di DKI Jakarta maka bagian utara akan lebih “bergoyang”.
Masih menurut Pak Masyhur, Kota-kota besar di dunia yang memiliki risiko gempa telah memiliki peta mikrozonasi, sehingga mereka terdukung dalam pembuatan perencanaan kontinjensi bila gempa terjadi.

Jadi, berbeda dengan pandangan umum bahwa manajemen bencana hanya melulu membicarakan tim tanggap darurat yang berisikan mereka-mereka yang jago mendirikan tenda untuk penampungan, P3K, penyediaan air bersih dan dapur umum. Manajemen bencana memerlukan ahli GIS dan Cartography baik yang berbasis sains maupun yang bersifat partisipatif.

Peran para ahli inilah yang dibutuhkan saat ini, baik untuk membuat peta risiko dan juga peta evakuasi, dan tentunya juga untuk mendukung pembuatan Rencana Tata Ruang dan Wilayah yang berbasis pada keamanan, ketangguhan, dan berkelanjutan. Dengan peta ini akan mempermudah penentuan titik-titik penampungan, baik berupa gedung-gedung maupun ruang terbuka hijau yang disaat normal dijadikan pusat kegiatan masyarakat dan dalam kondisi darurat menjadi tempat untuk memenuhi kebutuhan darurat dan kebutuhan dasar para penyintas (survovor).

Melalui forum ini saya mengajak kawan-kawan yang memiliki keahlian pada bidang GIS, P-GIS maupun pemetaan untuk menyumbangkan ilmunya untuk diamalkan pada ladang amal manajemen bencana untuk menyelamatkan kehidupan. Mari ! Kita mulai Δ

sumber : http://petapartisipatif.wordpress.com/2010/08/19/indonesia-butuh-peta-mikrozonasi-untuk-manajemen-bencana/


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