SPRUCE-ing up climate research

Oak Ridge National Lab scientist Paul Hanson

Oak Ridge National Lab scientist Paul Hanson Credit: Oak Ridge National Laboratory

As the planet warms up, natural systems will release more methane and CO2, adding to what’s being produced by humans. The more they release, the more heat will be trapped on the Earth, and the hotter we will get. Last month, I reported on a Nature paper that suggested that figures being used for how much will be released for each degree that temperatures rise have been over-estimated. So, I was interested to read in early February that the US Oak Ridge National Laboratory (ORNL) is planning to embark on an experiment to see how climate change will affect a sensitive bog forest in northern Minnesota. The project, called SPRUCE, will install a series of enclosures that can warm and raise the level of CO2 in the bog immediately around it. As well as monitoring how much this increases methane and CO2 output, the project will look at how vulnerable the eco-system is, and how it and the plants in it will respond.

Paul Hanson, who’s co-ordinating the project, told me that experiments like SPRUCE are needed to provide information about what will happen in predicted climate change scenarios that cannot otherwise be gathered today. “Many of the sustained warming conditions and associated changes in atmospheric composition have no analogue in the current world climate,” he told me, “especially for high latitude ecosystems where warming projections are highest.”

Hanson notes that only a small fraction of climate research is currently focussed on assessing the impact of global warming on biological systems in detail, like SPRUCE is. He feels that scientific discussion is moving on from establishing that climate change is real to predicting its likely outcomes, making this kind of information especially important. “Given this transition, it seems prudent to invest in experiments that address biological response and ecosystem feedback to the climate,” he said.

Schematic of the enclosures that the SPRUCE project that will use to study the impact of elevated CO2 levels and temperature on a north Minnesota bog

Schematic of the enclosures that the SPRUCE project that will use to study the impact of elevated CO2 levels and temperature on a north Minnesota bog Credit: Oak Ridge National Laboratory

SPRUCE is set to begin its first preparatory observations next year. Due to the time it will take to build the enclosures and get the necessary approvals, the warming and CO2 treatments are unlikely to start until 2013,  and will then go on for ten years. While much will have changed in that time, Hanson pointed out that such experiments must be well planned, and continue for a long period, to ensure their usefulness. “New studies must be thoughtfully planned and initiated to cover a range of plausible climate futures specifically because we won’t have time to continue to start new ones indefinitely.”

ORNL has already completed a large-scale field study on the effects of changed rainfall, increased CO2 emissions and higher temperatures in eastern Tennessee, Hanson explained. It found that established trees will survive reduced rainfall, and even benefit to some extent from raised temperatures and levels of CO2, which they use to create their food during daylight hours. However saplings will struggle with lower rainfall, as will non-forest plants. “The combination of warming with drying is detrimental to grassland species,” Hanson said.

To wrap up, I asked Hanson the question that is the main purpose of Simple Climate. If you were asked to simply explain the global warming situation to someone who had no previous exposure at all, how would you do it?

“What I tell my non-science friends and relatives is that the scientific evidence accumulated today, when interpreted through mechanistic models of how the Earth’s atmosphere, land and oceans function, suggest that greenhouse gases are accumulating in the atmosphere to unprecedented levels,” he said. “Our best explanation for this increase points to man’s abundant use of fossil fuels along with land use modifications. Then I point them to the same material that I read and encourage them to consider the information for themselves.”

That information, Hanson says, includes summaries of the International Panel on Climate Change Working Group I, which covers the physical science behind global warming.

The combination of warming with drying is detrimental to grassland species,” Hanson said.