In early 2009 the first two satellites to measure the global concentrations of carbon dioxide in the Earth’s atmosphere from space were launched. Both aimed to dramatically improve the way scientists monitor greenhouse gas emissions by replacing partial observation from sensors in aircraft, ships, and on the ground with the complete planetary coverage that only satellites can provide. Such measurements are vital to improving our understanding of the role of the terrestrial biosphere in the global carbon cycle, which, according to the Intergovernmental Panel on Climate Change’s Fourth Assessment Report, is the largest single source of uncertainty in the global carbon budget.
To reduce the uncertainty a huge scientific effort is required, from launching the satellite through to translating the satellite images and data into a usable format for the world’s climate change specialists. Working at such a cutting edge is not without risks. On 24 February 2009, shortly after takeoff, the NASA satellite known as the Orbiting Carbon Observatory failed to reach orbit and crashed back to Earth. Fortunately, a month earlier Japan’s GOSAT (Greenhouse Gases Observing Satellite) had successfully launched and is now sending back images and data on carbon dioxide and methane from 56,000 observation points over the Earth. Turning such images and data into maps and inventories and verifying their contents is essential to providing Earth System scientists with the information that, until now, they have been missing. IIASA over the past decade has been specializing in processing and verification of this type.
Between 2001 and 2005, IIASA worked with 13 partners, including the European Space Agency, as part of the EU-funded Siberia II project, which would become the first project to exploit the full range of electromagnetic wavelengths used by satellite sensors. The study, coordinated by Professor Christiane Schmullius of the University of Jena, Germany, showed that certain key processes, notably land cover and cryospheric dynamics (the dynamics of the frozen areas of the Earth), vegetation seasonality, and fire, can be recovered from satellite data. IIASA applied its ecological knowledge of Siberia’s forests to calibrate and validate the techniques needed for retrieving such information from the satellites. This, in turn, enabled the project to be the first to accomplish full greenhouse gas accounting (FGGA) for 3 million km2. FGGA compiles an inventory of all the greenhouse gas emissions that are emitted and removed from the atmosphere; it thus provides vital input for scientists to develop climate change models and for policymakers to set and monitor targets to reduce emissions.
The results of Siberia II brought scientists a step closer to understanding the way nature releases and absorbs carbon to and from the biosphere. But despite the uncertainty of the greenhouse gas accounting being reduced to half that previously reported, the uncertainty of the final results still remained at between 40 and 60 percent. More research was needed, particularly to better understand the Earth’s carbon sinks—the reservoirs that absorb carbon dioxide out of the atmosphere and store it.
Advances in space-based measurements of the Earth in theory offered the raw data for use as a basis for furthering this understanding. The Advanced Synthetic Aperture Radar (ASAR) on the European Space Agency’s Envisat satellite could measure boreal forest biomass well beyond levels previously reported by penetrating cloud cover and darkness and, most importantly, vegetation, to measure the quantity of biomass not visible to the human eye. Forests store the carbon they absorb in both biomass and soil; the boreal, mainly coniferous, forest ecosystems of high northern latitudes sequester much more carbon than tropical forests, making them one of the most significant carbon sinks in the world.
However, scientists still needed to reliably retrieve detailed biomass information from the images taken by the ASAR. A team led by Dr. Maurizio Santoro from the research consultancy, Gamma Remote Sensing, developed a new processing algorithm to produce a large-scale boreal forest biomass inventory and map from the satellite information. The team asked IIASA to provide validation sites for the development and testing of the algorithm and to review the subsequent procedures and results. “The algorithm provided unexpectedly good results,” says IIASA’s Professor Anatoly Shvidenko. “Besides helping researchers to better project future climate and biological processes, the maps can provide effective forest fire protection monitoring and other important forest management activities.” Indeed, forest wild fires can dramatically increase the amount of carbon released to the atmosphere. For example, thanks to the radar data and algorithm, we now know that the catastrophic Russian forest fire of 2003 emitted 270 million tons of carbon—more than the 250 million ton goal for emission reductions under the Kyoto Protocol.
Land Use in Russia. Combining satellite information with measurements taken on the ground, IIASA produced the above map of Russia showing land cover uses for every kilometer. Such maps serve as a basis for accounting for the release and take up of greenhouse gas emissions.
The success of any future international agreement to tackle climate change that succeeds the Kyoto Protocol relies on the ability to accurately monitor countries’ greenhouse gas emissions and compare these with agreed targets. One of the main goals of the GOSAT mission, managed by a consortium of the Japan Aerospace Exploration Agency, Japan’s Ministry of the Environment, and Japan’s National Institute for Environmental Studies (NIES), is to measure carbon dioxide and methane across the globe. The NIES team led by Dr. Shamil Maksyutov has asked IIASA to independently verify the measurements. IIASA is using its vast databases of land resources and estimates of carbon in the terrestrial ecosystems from ground observations to rigorously compare with and therefore validate the data from the satellite. Increasing the quality of data on land cover is an ongoing challenge for scientists, and IIASA has recently developed an innovative tool, Geo-Wiki, that enrolls the help of a global network of volunteers to check land cover information.
Because of the huge costs involved in launching satellites, space agencies always conduct extensive studies into the feasibility and benefits of new satellite missions. Currently, the European Space Agency is assessing the scientific focus of the Earth Explorer mission due to be launched in 2016. One of the final three candidate missions is BIOMASS which aims to acquire global measurements of forest biomass to assess terrestrial carbon stocks and fluxes by using, for the first time, radar with the P-bandwidth which is uniquely sensitive to forest biomass. Work by IIASA has helped to demonstrate the feasibility and benefits of such a cutting-edge scientific mission which is expected to cost in the region of €150 million. If BIOMASS is selected as the satellite mission, it will provide an efficient and cost-effective tool to consistently measure biomass on the ground and so allow another crucial step to be taken not only toward reducing the uncertainties surrounding the spatial distribution of carbon stocks and carbon exchange, but also in estimating carbon emissions due to human-induced or natural disturbances.
The Benefits of Global Earth Observation.
Scientists today are increasingly turning to satellites for a comprehensive overview of what is occurring in the environment. Despite satellites costing millions of euros to launch, the social, economic, and environmental benefits of the data they provide easily outweigh the costs. The EU-funded project GEOBENE, led by IIASA with 12 partners, systematically studied the benefits of global earth observation. The project covered nine areas: disasters, health, energy, climate, water, weather, ecosystems, agriculture, and biodiversity. The benefits of global earth observation were huge. For example, it enabled agribusinesses to spot where fertilizer needed to be applied, thus helping them boost crop yields, and provided early warnings of water shortages. The study also demonstrated how satellite data could improve weather forecasts, target conservation efforts more effectively, and make the planning of food operations more efficient.
Last edited: 28 August 2012
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