Climate change and Copenhagen are dominating the world news this week, as politicians, diplomats, scientists, and protesters gathered in the Danish city for the 2009 meeting for the U.N. Framework Convention on Climate Change.
Whether or not you agree that humans are causing global warming by releasing carbon dioxide into the atmosphere, there is a bottom line everyone must address: It is critical to have reliable data on where that greenhouse gas is coming from and where it is going.
And whatever agreement, deal, or treaty comes out of Copenhagen, that reliable data is imperative to monitoring compliance. This is where space science becomes a key player on the international political stage.
From Earth orbit, a satellite can look down day after day, surveying most of the globe, and measuring where carbon dioxide is being released into the atmosphere (a source) and where it is being removed (a sink, in scientific jargon.) In fact, this is exactly what the Orbiting Carbon Observatory (OCO) was planned to do. Unfortunately for us all, last February OCO fell victim to launch failure.
OCO was a proof-of-concept mission to demonstrate that sensitive remote-sensing instruments in space can measure the carbon dioxide in a column of air all the way down to the ground, with a three-kilometer-square "footprint" that would allow it to pinpoint carbon sources and sinks.
In Copenhagen, negotiators are wrangling over carbon-dioxide emissions targets (among other knotty topics.) Nations may commit to meeting specific targets. But will they meet those goals?
As a former U.S. president liked to say, "Trust, but verify." Right now, there exists no way to gather the global measurements necessary to verify that any scheme being negotiated, like much-touted cap-and-trade, is working.
Consider a cap-and-trade scheme, where instead of reducing its carbon emissions, an industry or country can opt to purchase "carbon offsets," perhaps by paying another entity to plant more trees in a rainforest to take up the carbon released by coal-fired power plants elsewhere. But how would treaty enforcers know if the trees really are taking up the same amount of carbon released from the coal?
Ground-based monitoring is effective over limited regions. In fact, satellite researchers rely on such stations for the "ground truth" to confirm that their remote sensors are working. But surface-monitoring stations cannot cover the globe. Some regions, like North America and Europe, do have good measurement networks, but other regions, because of their remoteness or political unrest, are seriously lacking reliable sources of information.
Over most of Earth's surface -- the part covered in ocean -- few measurements are routinely taken. Because oceans are the biggest sink for carbon dioxide, taking up perhaps 25 percent of what we humans emit, knowing how much they are taking up and releasing will solve a big piece of the climate-change puzzle.
On land, we really don't know yet what processes are taking up the carbon. For example, in tropical regions where the trees that form the great rainforests can either soak up carbon dioxide as they grow or release it as they are felled and burned, there is next to nothing in the way of monitoring stations.
So, if a signatory to whatever agreement comes out of Copenhagen commits to a net reduction in carbon dioxide emissions, but fudges the data meant to verify the reduction, there is likely to be no way to monitor truthfulness.
This returns us to the space-based solution to the verification problem: Monitor the carbon sources and sinks from orbit. As David Crisp, OCO Principal Investigator says, "From space, you can look over everyone's shoulder."
This brings us to the question: Will OCO fly again? The answer will depend on the outcome of budget wrangling that will take place over the next couple of years between the U.S. Administration and the Houses of Congress.
Yesterday, a joint House-Senate conference committee released its appropriations detailing how they want NASA to spend its money in 2010. They directed $50 million to keep alive the possibility of reflying OCO, with $25 million in new money and $25 million to come out of the "prior year balances" of the Space Science Directorate within NASA, which is effectively a lien on other science programs.
Space science is never easy, and the laborious and convoluted process of getting money to fly the spacecraft can make it painful. In a following post, I'll address that pain.