Satellite observation set to fill gaps in understanding of carbon cycle
Scientists' understanding of the flux of carbon between the oceans, atmosphere, land and biosphere - the so-called carbon cycle - is set to dramatically improve with the introduction of satellite observation technologies. On June 6, more than 60 researchers from Europe, the US and Japan gathered in Italy for a three-day workshop entitled Carbon from Space, co-organised by the European Space Agency (ESA). It was an opportunity to learn about the missions being launched by all three partners in the coming years that will make carbon dioxide (CO2) measurement from space a reality. 'Direct satellite measurements of carbon dioxide will have as dramatic an impact as the Hubble Space Telescope within the Earth science field,' according to Philippe Ciais of the French Laboratory for Climate Sciences and the Environment (LSCE). 'It should give us a completely new picture of something more or less completely unknown, showing us the carbon flux across tropical areas such as South America and Africa, where we basically have no data available right now.' It is well known that human activity - particularly the burning of hydrocarbons that were previously locked up in the Earth - has dramatically increased levels of atmospheric CO2. But only around half of the carbon dioxide released through human activity actually stays there, as unidentified 'sinks' on land or the surface of oceans absorb the rest. However, scientists cannot be sure of the continuation of this effect without a better understanding of its distribution and strength. While satellite observation of another greenhouse gas - carbon monoxide - is well established, carbon dioxide is longer-lived and mixes well in the air, making it a much harder target for space-based observation. The most significant knowledge gaps exist in scientists' understanding of the exchange or 'flux' of carbon between the land surface and atmosphere. Nevertheless, the workshop heard that CO2 has been observed experimentally using sensors aboard NASA's weather and climate research satellite Aqua. In the near future, scientists' capacity to measure CO2 from space will increase as NASA launches its Orbiting Carbon Observatory in 2007, and the Japan Aerospace Exploration Agency (JAXA) launches its own Greenhouse gasses Observing Satellite (GOSAT) in 2008. Within ESA, meanwhile, proposals are currently being considered for science missions studying various aspects of the carbon cycle as part of the next round of Earth Explorers. Furthermore, a proposed new generation of Sentinel spacecraft would also include geostationary and orbiting satellites for atmospheric observation. According to another participant in the workshop, LSCE's Peter Rayner, the event provided a valuable opportunity to learn what new types of carbon-related data would be made available using satellite technology, ensuring that ground-based activities to support and validate these missions could be coordinated, and that remaining knowledge gaps to be tackled in the future could be identified. 'The new spacecraft are reliant on reflected sunlight, for instance, but the carbon cycle does not stop when areas are in darkness,' he concluded. 'Other methods will need to be developed to learn more.'
Countries
Japan, United States