NASA UNVEILS CO2 SATELLITE MAPPING TOOL

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite is proving a precise and sophisticated tool for tracking carbon-dioxide in the atmosphere, and its effect on climate in conjunction with water vapour, reports ScienceDaily.

The new data, which span the seven-plus years of the AIRS mission, measure the concentration and distribution of carbon-dioxide in the mid-troposphere--the region of Earth's atmosphere located between 5-12 kilometers (3-7 miles), above Earth's surface. They also track its global transport. The product represents the first-ever release of global carbon-dioxide data based solely on observations. The data have been extensively validated against both aircraft and ground-based observations.

In another major finding, scientists using AIRS data have removed most of the uncertainty about the role of water vapour in atmospheric models. The data are the strongest observational evidence to date for how water vapour responds to a warming climate.

"AIRS temperature and water vapour observations have corroborated climate model predictions that the warming of our climate produced as carbon-dioxide levels rise will be greatly exacerbated--in fact, more than doubled--by water vapour," said Andrew Dessler, a climate scientist at Texas A&M University, College Station, Texas.

He explained that most of the warming caused by carbon-dioxide does not come directly from it but from effects known as feedbacks. Water vapour is a particularly important feedback. As the climate warms, the atmosphere becomes more humid. Since water is a greenhouse gas, it serves as a powerful positive feedback to the climate system, amplifying the initial warming. AIRS measurements of water vapour reveal that water greatly amplifies warming caused by increased levels of carbon-dioxide. Comparisons of AIRS data with models and re-analyses are in excellent agreement.

"The implication of these studies is that, should greenhouse gas emissions continue on their current course of increase, we are virtually certain to see Earth's climate warm by several degrees Celsius in the next century, unless some strong negative feedback mechanism emerges elsewhere in Earth's climate system," said Dressler.