Scientists for the first time have actually seen the effects greenhouse gases -- mostly carbon dioxide -- have on the Earth's surface temperature.

The landmark achievement proves the climate-changing greenhouse effect exists, and is worsening.

A research team led by scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory measured the capacity of atmospheric carbon dioxide to absorb heat given off by the Earth's surface over an 11-year period.

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Research has long shown that releasing huge amounts of carbon dioxide into the atmosphere will produce a "greenhouse gas effect" in which heat that otherwise would dissipate into outer space is trapped by a blanket of gases in the atmosphere that absorbs it.

Scientists report they've now actually seen the process at work, confirming climate model predictions.

"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 lead author Daniel Feldman, a scientist at the Berkeley Lab's Earth Sciences Division, in the statement.

"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 observations were made at two locations in North America: one in Oklahoma and one on the North Slope of Alaska, from 2000 to the end of 2010. Scientists measured atmospheric CO2's contribution to radiative forcing at both sites.

Radiative forcing measures how much the Earth's energy balance is perturbed by atmospheric changes. Positive radiative forcing occurs when the Earth absorbs more energy from solar radiation than it emits as thermal radiation back to space.

They found that CO2 was responsible for a significant uptick in radiative forcing at both locations.

Researchers used state-of-the-art high precision spectroscopic instruments that measure the thermal infrared energy that travels from the atmosphere to Earth's surface. The instruments are able to detect CO2 by its unique spectral signature.

They found that atmospheric carbon dioxide concentrations prevented thermal radiation from escaping into space so the Earth absorbs more solar heat that it emits back into space.

These high concentrations of carbon are directly linked to the burning of fossil fuels, said the researchers.

"We measured radiation in the form of infrared energy," explained Feldman. "Then we controlled for other factors that would impact our measurements, such as a weather system moving through the area."

The research will be published Feb. 25 in the advance online issue of the journal Nature.