Nasa satellite will track earth’s ability to absorb carbon dioxide

A Nasa satellite being prepared for launch today is expected to reveal details about where carbon dioxide, a greenhouse gas tied to climate change, is being released into earth's atmosphere on a global scale.

The two-year, US$465 million project, known as the Orbiting Carbon Observatory (OCO), will also be able to pinpoint where the planet's forests and oceans are reabsorbing atmospheric carbon, a cycle that is key to the earth's temperature.

More than 50 years of measurements show that about half the amount of carbon dioxide put into the atmosphere - by natural processes and human activities - ends up being reabsorbed.

"What's quite remarkable is that over time, half of what we've released has been absorbed by the plants or the ocean, but it's very variable from year to year," OCO project manager Ralph Basilio, with the US space agency's Jet Propulsion Laboratory in Pasadena, California, said during a prelaunch conference.

"Understanding what controls that variability is really crucial. If we can do that today, it might inform us about what might happen in the future," he said.

The observatory will be positioned 705 kilometres above the planet and inclined so that it passes over the same point on earth at the same time every 16 days, giving scientists insight into how levels of carbon dioxide change over weeks, months and years.