Cressie is director of the Centre for Environmental Informatics in the National Institute for Applied Statistics Research Australia (NIASRA), professor of statistics, and Distinguished Professor at the University of Wollongong, Australia. He is also Distinguished Visiting Scientist at NASA's Jet Propulsion Laboratory and Adjunct Professor at the University of Missouri.
At RSS Conference this afternoon, he delivered the Barnett Lecture, explaining the role statistics plays in the science of climate change. In particular, he discussed how to model carbon dioxide (CO2) in the atmosphere using remote sensing data from the OCO-2 satellite, a NASA craft that circles the Earth 14 times a day, collecting readings.
The resulting maps and measures of carbon, and the associated uncertainties, are an important part of the climate change picture. But the primary interest, said Cressie, is in solving an inverse problem: to determine the sources and sinks of CO2 – the ‘sinks’ being parts of the environment, such as forests or oceans, that are able to absorb CO2 from the atmosphere. Understanding where carbon comes from, and where it might go will be key to any climate change mitigation strategy.
The Paris climate agreement, which comes into force in 2020, pledges to keep global warming below 2oC – though, on current evidence, it seems unlikely we’ll be able to keep to this target. “We are already on the way to 1.2oC,” Cressie said.
It is estimated that we need only release an extra 565 gigatons of CO2 into the atmosphere to bring warming to 2oC, yet there’s still an estimated 2,795 gigatons of CO2 locked away in the ground as fossil fuels. It’s fine if the CO2 stays there, of course. But, as Cressie pointed out, there is a lot of financial and economic pressure on companies to get that carbon out of the ground.
Cressie said: “We want to try to stop carbon getting out of the Earth’s surface and into the atmosphere, and to take it out of the atmosphere where possible”. As such, he said, “we want to know where the carbon sinks are”.
He explained that while this “flux-field (sources and sinks) estimation” is hard, it is essential both for decision-making and treaty verification. “Our future depends on it,” read his final slide.