Could the gushing BP well help explain an ancient climate mystery?
Today, a crew of scientists are setting off for roughly 10 days to take measurements near the gushing well at the bottom of the Gulf of Mexico—but they're not looking for oil. Oceanographer John Kessler of Texas A&M University, College Station, and his colleagues have been awarded a grant by the National Science Foundation for a research cruise on the R/V Cape Hatteras, to measure concentrations of methane gas. Methane makes up about 40% by mass of what's spewing out of the well, according to measurements by BP.
The purpose of the cruise is twofold, Kessler says. How much oil has entered the gulf is the question on everyone's minds. (Oceanographer David Valentine of the University of California, Santa Barbara, also on the cruise, thinks measuring the methane could give a better estimate of oil flow than video or satellite imagery.)
But the burst well has also become an unlikely scientific windfall for Kessler, who studies natural methane seeps and their link to rapid climate change. Scientists think sudden, violent outflows of the gas from the sea floor might have spiked the planet's temperature about 55 million years ago, and they think the gulf spill affords them the unique opportunity to study an analog in real time.
Samples of ancient carbon deposits from this era show a marked increase in concentrations of carbon-12 relative to its heavier isotope carbon-13, indicating a lot of lighter carbon might have been suddenly released at the time.
"To cause this type of global isotopic shift, you'd have to take all terrestrial plants and burn them into carbon dioxide," Kessler says, which seems unlikely. That's led scientists to look for other culprits. "But if you look at methane in the sea floor, it's the lightest carbon source [isotopically] on the planet." So many scientists think a sea floor methane release is responsible. Additionally, because methane is a greenhouse gas roughly 25 times more potent than carbon dioxide, a big release would fit with "evidence that the temperature of the planet rose very dramatically" at that time, Kessler says.
But in the case of a big release of undersea methane, how much would escape the ocean to exert its greenhouse effects? "Knowing if it's 1% or 90% that makes it out to the atmosphere will be a very big discovery for us," says Kessler. If the methane stays dissolved, it could trigger a feeding frenzy among microbes, he says. Their consumption of oxygen could create hypoxic zones and have "a serious influence on biodiversity at those times as well,"
Answering these questions is "something we haven't been able to do without running the experiment," he says. The burst well offers just such an experiment, though at a smaller scale. So Kessler scrambled to arrange the cruise in less than 3 weeks, a process which usually takes 4 to 6 months. "Obviously, no one's ever going to allow us to dump tons of methane into the ocean to simulate one of these natural massive eruptions," says Kessler. (The amount of methane being released by the well is too little to affect climate, he says.)
But conducting a rigorous scientific study in a disaster zone has its own drawbacks, he acknowledges. "We're going to get as much as we can without being in the way," he says. They'll have to work around cleanup and containment efforts, but he says he's determined to both "get as close as we can to ground zero" and map the full extent of the plume "to get a very comprehensive map."
When it's time to place his instruments in the water, the real nail-biting begins, he says. Oceanographers generally don't usually work in oil slicks, which might damage their equipment. "Sending our instruments down through this layer of oil is something that's keeping me up at night."
Given the disaster unfolding in the gulf, says Kessler, "if we can make a little lemonade out of the lemons we've been given, then at least maybe some good will come of this."
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