It is no secret that greenhouse gas emissions, and especially carbon dioxide, are on the rise much to the alarm of governments, scientists and environmentalists around the globe. These gases get their name from their effect of trapping the suns energy inside the atmosphere causing temperatures to rise. However, scientists have not directly observed this effect, until now.
In a paper published in Nature, researchers from the Lawrence Berkeley National Laboratory examined ten years of data taken between 2000 and 2010 on Alaska's North Slope and in Oklahoma. The instruments at each location examined the concentrations of carbon dioxide and the effect of "radiative forcing," which occurs when more radiation from the sun is absorbed than is reflected back into space. Researchers saw "the fingerprint of carbon dioxide" trapping heat in action, said the study author Daniel Feldman. According to Feldman, no other researcher had looked in the atmosphere for this type of proof of climate change before.
"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," Feldman says. "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."
Both locations utilized spectrometers capable of identifying individual components of the atmosphere. Using these instruments, researchers were able to directly look at the CO2 in the atmosphere and see how much infrared radiation was emitted from the carbon dioxide.
The increase in energy to the atmosphere is about 0.2 Watts per square meter per decade. And while this may seem insignificant, the surface of the Earth is 196.9 million square miles, so this figure adds up.
In doing so, the data show clouds, water vapor and changes in sun's radiation are not responsible for warming the air, as some who doubt mainstream climate science claim, Feldman says. Nor could it be temperature data being tampered with, as some contrarians insist.
Researchers also noticed changes in the data. For example, in the spring, when plants bloom and grow, they use more carbon dioxide causing the amount of radiative forcing to decline.
"The data say what the data say," Feldman says. "They are very clear that the rising carbon dioxide is actually contributing to an increased greenhouse effect at those sites."
