Nature & Environment

Scientists Directly Measure the Greenhouse Effect for the First Time

Catherine Griffin
First Posted: Feb 26, 2015 09:35 AM EST

Scientists have witnessed an increase in carbon dioxide's greenhouse effect at Earth's surface for the very first time. The findings reveal a warming effect that's being directly affected by rising CO2 levels in the atmosphere.

Scientists have long known that CO2 influences the balance between incoming energy from the sun and outgoing heat from the Earth. However, this effect has not been experimentally confirmed outside of the laboratory. Now, scientists have managed to make direct measurements.

The researchers measured atmospheric carbon dioxide's contribution to radiative forcing at two sites: one in Oklahoma and one in Alaska. Radiative forcing is a measure of how much the planet's energy balance is perturbed by atmospheric changes. Positive radiative forcing occurs when Earth absorbs more energy from solar radiation than it emits as thermal radiation back to space. IT can be measured at Earth's surface or high in the atmosphere.

In the end, the researchers found that CO2 was responsible for a significant uptick in radiative forcing at both locations-about two-tenths of a Watt per square meter per decade. The scientists also linked this trend to the 22 parts-per-million increase in atmospheric CO2. Much of this gas was due to the burning of fossil fuels.

"We see, for the first time in the field, the amplification of the greenhouse effect because there's more CO2 in the atmosphere to absorb what the Earth emits in response to incoming solar radiation," said Daniel Feldman, lead author of the new paper, in a news release. "Numerous studies show rising atmospheric CO2 concentrations, but our study provides the critical link between those concentrations and the addition of energy to the system, or the greenhouse effect."

The findings reveal a directly measured correlation between rising CO2 levels and heating. This, in turn, may help with future studies. The measurements enabled the scientists to detect the influence of photosynthesis on the balance of energy at the surface. This may lead to future findings.

The findings are published in the journal Nature.

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