New evidence from satellites orbiting the Earth has put an end to an doubts about whether greenhouse gases are actually increasing.
Until now, researchers depended on ground-based measurements and theoretical models to measure the increase. New sets of data taken from two satellites orbiting the Earth have now provided the first directly observable evidence of a rise in greenhouse gases.
?It?s the first time that we have seen observationally that these changes are really having an effect on the radiative forcing of the climate,? said Dr. Helen Brindley, an atmospheric physicist at Imperial College in London. Radiative forcing is the measure of the climate effects of greenhouse gases.
By comparing the two sets of data, Brindley and her colleagues have shown a change in greenhouse gas emissions from Earth over the past 27 years which agrees with ground-based measurements.
?Because we know where in the spectrum certain greenhouse gases are observed, when we look at the changes between the two periods, we can say that change is due to changes in CO2 or methane,? Brindley said. ?There has been quite a significant change over the past 30 years, particularly in methane.?
Methane, one of the most powerful greenhouse gases, is emitted from landfill sites and disused mines. A disturbing new source of methane could be melting tundra, during unusually hot arctic summers.
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