It has been known for a long time that atmospheric carbon dioxide influences the planet’s natural energy balance, that is, the equilibrium between incoming energy from the Sun and outgoing heat from the Earth. However, until now, this effect had never been directly observed (outside the lab).
A team of scientists from the US Department of Energy’s Lawrence Berkeley National Laboratory found their proof from two sites – one in Oklahoma and the other on the North Slope of Alaska, after measuring CO2’s heat-trapping ability over an 11-year period.
Between 2000 and 2010, atmospheric CO2 increased by a staggering 22 parts-per-million, thanks in large part to the burning of fossil fuels, researchers say. And while this shows a rise in CO2, how does it prove it contributed to the greenhouse gas effect? For this, the team used special spectroscopic instruments to measure radiative forcing – the rate at which the atmosphere warms up.
It turns out that because of the recent surge in atmospheric CO2, radiative forcing has increased two-tenths of a Watt per square meter per decade. This may not seem like a lot, but in relative terms, it’s significant. "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," Daniel Feldman, a scientist in the Berkeley Lab and the study’s lead author, said 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," he added. What’s even more concerning is that the greenhouse effect doesn’t seem to be letting up anytime soon. Just last year, greenhouse gas levels hit a record high, with a 34 percent increase in radiative forcing. The findings reveal a directly measured correlation between rising CO2 levels and heating, a link that was mathematically proven just two months ago.