Scientists witness greenhouse effect

Scientists have for the first time actually observed an increase in carbon dioxide's greenhouse effect at the Earth's surface. They attributed this upward trend to rising emissions from the burning of fossil fuels. 

The influence of atmospheric carbon dioxide (CO2) on the balance between incoming energy from the Sun and outgoing heat from the Earth - the planet's so-called 'energy balance' - is well established. However, this effect has not been experimentally confirmed outside a laboratory until now.

A team of researchers - led by the US Department of Energy's Lawrence Berkeley National Laboratory (LBNL) - measured atmospheric CO2's contribution to radiative forcing at two research facilities - one in Oklahoma, the other on the North Slope of Alaska. Radiative forcing is a measure of how much the planet's energy balance is disrupted by atmospheric changes. Measurements were taken between 2000 and the end of 2010.

The result is two sets of readings over 11 years from two very different locations , and includes 3300 measurements from Alaska and 8300 from Oklahoma obtained on a near-daily basis.

The researchers found that CO2 was responsible for a significant increase in radiative forcing at both locations, about 0.2 Watts per square metre per decade. They linked this trend to the 22 parts-per-million increase in atmospheric CO2 over the eleven-year period. Much of this CO2 is from the burning of fossil fuels, according to the National Oceanic and Atmospheric Administration's CarbonTracker modelling system that monitors CO2 sources around the world.

According to LBNL, the results agree with theoretical predictions of the greenhouse effect due to human activity. It says it also provides further confirmation that the calculations used in today's climate models are on track when it comes to representing the impact of CO2.

Lead author of the research paper, LBNL's Daniel Feldman, said, "We see, for the first time, 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." He added, "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 research was reported yesterday in the advance online publication of the journal Nature.

Researched and written
by World Nuclear News