The new modeling system simulated 10 years of phytoplankton development. Each map corresponds to the biomass density of one of the 18 dominant phytoplankton types. Red areas indicate the highest density. Global climate models are missing a good chunk of plant information that could significantly alter long-term climate change predictions. A new technique for modeling phytoplankton -- microscopic plants in the upper layers of the Earth's waters -- could reveal a much more accurate picture.
"(Other) modelers have populated their oceans with three or four kinds of plants, said Mick Follows, a researcher in MIT's Program in Atmospheres, Oceans and Climate. "We’ve represented a much more diverse community, and allowed it to have interactions that regulate it more naturally."
Phytoplankton populations are constantly changing, which makes them difficult to predict. So the MIT researchers developed an algorithm using evolutionary principles to more accurately represent the microscopic plants. A more precise count is important because phytoplankton process carbon dioxide -- a significant contributor to global warming.
Scientists interviewed for this article said it's too soon to say whether the more accurate phytoplankton count will be good news or bad news for the global climate's future. But climate researchers will have a more accurate picture once they factor the new phytoplankton model into their estimates, they said.
Phytoplankton perform two-thirds of all the Earth's photosynthesis -- the process by which plants turn light, nutrients and carbon dioxide into food. The amount of CO2 processed by phytoplankton during photosynthesis affects concentrations of CO2 in the water, which determines how much of the greenhouse gas the oceans can absorb.
Follows and his colleagues created a model ocean seeded with dozens of randomly generated types of phytoplankton. Like the real ocean, the model accounted for variations in light, temperature and food.
Having set the parameters, Follows' team turned the model on. Over 10 simulated years, the digital creatures competed to survive. Some died out, others flourished, and they gradually settled into their respective niches.
Current marine-modeling systems don't factor in the phytoplankton's ever-evolving nature.
"We know that if climate changes a lot, the oceanic ecosystem will change," says Raleigh Hood, a University of Maryland oceanographer. "This model has the power to change itself under changing conditions."
When they compared the resulting phytoplankton patterns to real-world data, the team found that their results were similar to those measured in the sea.
The data, published recently in Science, could profoundly impact climate models.
"It’s a major breakthrough," says Jorge Sarmiento, director of the Atmospheric and Oceanic Sciences program at Princeton University. "It will help us better predict how global warming will affect ocean biology and the carbon cycle."
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