The world's first satellite designed to map concentrations of carbon dioxide in the Earth's atmosphere will be launched by Nasa on Monday.

The Orbiting Carbon Observatory (Oco) will collect precise measurements of the greenhouse gas in the Earth's atmosphere, identifying where it is coming from, where it is absorbed and what happens to it in between.

This improved tracking of CO2 will help scientists develop maps how the gas is concentrated around the world and give a better picture of how it affects the Earth's climate. Policymakers and governments will be able to use the data when setting and monitoring CO2 emissions targets designed to tackle climate change.

"It's critical that we understand the processes controlling carbon dioxide in our atmosphere today so we can predict how fast it will build up in the future and how quickly we'll have to adapt to climate change," said David Crisp, principal investigator for the OCO, based at Nasa's Jet Propulsion Laboratory in Pasadena, California.

The Oco will blast off on a Taurus XL rocket from Vandenberg Air Force Base in California in the early hours of Monday morning (watch the video here). It will help scientists answer one of the biggest mysteries about the movement of CO2 in the Earth's atmosphere. Of all of the greenhouse gas emitted into the air since the industrial revolution in the 19th century, around 40% has stayed thee. Half of the remainder has been absorbed by the Earth's oceans but the rest has not yet been be accounted for. Scientists think the gas must have been absorbed on land but no one really knows where these missing carbon sinks are or what controls them.

"It's important to make clear that the 'missing' sinks aren't really missing, they are just poorly understood," said Scott Denning, an atmospheric scientist at Colorado State University. "We know the 'missing' sinks are terrestrial, land areas where forests, grasslands, crops and soil are absorbing carbon dioxide. But finding these sinks is like finding a needle in a haystack. It would be great if we could measure how much carbon every tree, shrub, peat bog or blade of grass takes in, but the world is too big and too diverse and is constantly changing, making such measurements virtually impossible. The solution is not in measuring carbon in trees. The solution is measuring carbon in the air."

Previous Nasa missions, such as the Atmospheric Infrared Sounder, have also measured the amount of carbon dioxide in the Earth's atmosphere but only at altitudes of 5km to 10km above the surface. "Oco is the first Nasa mission that has been dedicated, and optimised to make precise measurements of carbon dioxide throughout the atmospheric column, between the surface and space, with the greatest sensitivity near the Earth's surface, where most of the carbon dioxide sources and sinks are thought to be located," said Crisp.

Oco will collect about 8 million measurements every 16 days for at least two years. It will use three high-resolution spectrometers to split light into its various constituent colours. By anlaysing this light to detect the unique signature of gases such as carbon dioxide and oxygen in the atmosphere, scientists will be able to determine their relative concentrations and identify sources and sinks of CO2.

"Oco is primarily an exploratory science mission, whose objective is to test and validate a new technique for measuring carbon dioxide in the Earth's atmosphere from space. If we find that this approach works as well as we predict, it should provide scientists with the data that they need to produce the first global maps of carbon dioxide sources and sinks on regional scales, or spatial scales comparable to the size of Great Britain," said Crisp.