September 4, 2013
Breathing Earth Seen From Space, CO2 Levels Still Rising
Lee Rannals for redOrbit.com - Your Universe Online
Ten years of data taken from the European Space Agency's (ESA) Envisat mission and Japan's Greenhouse gases Observing Satellite (GOSAT) show that carbon dioxide increased by about 0.5 percent every year between 2003 and 2013. The measurements also show that methane began increasing by 0.3 to 0.5 percent per year from 2007 on.
The ESA says that the main reason for the increase in carbon dioxide over the last ten years is the burning of fossil fuels like coal, oil and natural gas. The story behind why methane is increasing is a little less clear, but current evidence points to man-made emissions combined with wetland emissions and biomass burning.
Scientists say they are observing the Earth "breathing" carbon dioxide in the northern mid to high latitudes. This happens because the carbon exchange between the atmosphere and vegetation is particularly large, with forest sequestering carbon during the summer, or "inhaling," and releasing the gas during the winter, or "exhaling."
“Some carbon dioxide models tend to underestimate the strength of the ‘breathing’, but we have to investigate this further using different models and methods,” said physicist and greenhouse gas expert Dr Michael Buchwitz from Germany’s University of Bremen.
“The goal of the GHG-CCI project is to generate high-quality global distributions of atmospheric carbon dioxide and methane, yielding improved information about the regional sources and sinks of these two important climate relevant gases. This is needed to improve climate predictions."
Satellite maps have revealed regions where methane levels are particularly high, but determining emission levels requires sophisticated model-based methods because atmospheric transport needs to be taken into account.
“The satellite data enable us to obtain detailed spatial patterns of methane emissions globally, which cannot be derived from the sparse surface observations, although these measurements are much more accurate,” said Dr Peter Bergamaschi, a scientist from the European Commission’s Joint Research Centre in Ispra, Italy.
Buchwitz says that continuing to understand the natural and man-made influences on atmospheric gases is key. He added that he hopes that the carbon dioxide data gap between GOSAT and the candidate CarbonSat mission can be closed by NASA's Orbiting Carbon Observatory -2 (OCO-2) mission and the planned GOSAT-2.
NASA's OCO-2 satellite is based on the original OCO mission and is expected to launch sometime in July 2014. This satellite includes three high-resolution grating spectrometers that will be able to take precise measurements of carbon dioxide in the atmosphere. Instruments like this will enable scientists to keep an even better eye on how our world is evolving as a result of climate change.