NASA's Orbiting Carbon Observatory and its Taurus booster lift off from Vandenberg Air Force Base. Credit: Orbital Sciences Corporation

A satellite designed to answer one of the biggest remaining questions in climate-change science has fallen into the ocean after a launch failure, the Associated Press reports.

The amount of climate change in the next decades could be much more or much less than currently predicted because of a significant gap in scientists' knowledge. One of the greatest uncertainties in predicting climate change is what natural mechanisms are involved in capturing carbon dioxide. Currently, on average, half of the carbon dioxide released by burning fossil fuels is taken up by oceans and plants; it doesn't remain in the atmosphere, so it doesn't contribute to global warming. But because scientists don't know precisely which mechanisms are involved or necessarily how they work, they're not sure that this will continue.

There are two distinct possibilities. First, the mechanisms could shut down. For example, some argue that the oceans won't be able to absorb much more carbon dioxide, and may even start releasing some of what they've absorbed so far, speeding climate change. On the other hand, other natural mechanisms for absorbing carbon dioxide could actually increase in the future, slowing global warming.

The differences between the two could be extreme. Even now, from year to year, the amount of carbon dioxide that's absorbed varies widely: sometimes none of the carbon dioxide emitted by fossil fuels is absorbed; sometimes just about all of it is (though this is likely due to weather variations, including droughts, and not necessarily due to long-term trends).

The satellite was designed to help scientists determine which mechanisms are dominant by allowing them to trace where carbon dioxide is being absorbed, and how much. Ground-based measurement stations aren't up to the task.

Money in the stimulus bill directed toward NASA and the National Oceanic and Atmospheric Administration could pay for a new carbon-dioxide monitoring satellite. A Japanese satellite launched earlier this year is also gathering information about carbon dioxide, but with significantly less resolution than the NASA satellite.