Washington: Ten years of satellite observations of greenhouse gases have revealed the rise of carbon dioxide in the atmosphere.
They also showed that recent methane increases are likely due to manmade emissions.
Atmospheric carbon dioxide and methane are the two most important manmade greenhouse gases responsible for global warming.
Measurements from ESA`s 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. After years of stability, methane began increasing by 0.3-0.5 percent per year from 2007 on.
The main reason for the increase in carbon dioxide over the last ten years is emissions from burning fossil fuels, such as coal, oil and gas.
For methane the reason is less clear, but is most likely due to increasing manmade emissions, combined with natural variations caused by wetland emissions and biomass burning.
For carbon dioxide, seasonal fluctuations are the largest, caused by variations in the photosynthesis of vegetation. The observed `breathing` is largest in northern mid to high latitudes. This is expected since there the carbon exchange between the atmosphere and vegetation is particularly large, with forests sequestering carbon during the summer (`inhaling`), part of which is released during winter (`exhaling`).