Over the last several years, the greenhouse effect has gotten something of a bum rap. Despite any debates on the existence or extent of global warming, the greenhouse effect keeps the globe warm, period. The greenhouse effect is simply the role the atmosphere plays in insulating the earth's surface. Without it, scientists estimate that the temperature on earth would be about 0 F.
Solar radiation passes through the atmosphere, hits the earth, and some of it is absorbed. The rest bounces off the earth's surface. Some of this reflected radiation passes back into space, and the rest is absorbed by greenhouse gases, such as carbon dioxide, methane, nitrous oxide, and even plain old water vapor. The trapped radiation then does what its name implies and radiates back out of the gases, hitting the earth again and heating it further.
Natural processes—photosynthesis, for example—keep these greenhouse gases in check, removing them from the atmosphere and effectively regulating their concentration. But as more and more of the gases are introduced into the atmosphere, those natural processes don't necessarily increase their pace. The burning of fossil fuels releases six billion tons of carbon into the air every year, and deforestation by the burning of trees contributes another three billion. The ocean, however, isn't absorbing more carbon dioxide, and the trees that are left aren't photosynthesizing it away at any greater a rate.
A resonant view
Not all of Kalinichev and Kirkpatrick's geochemical research haunts the processors of a supercomputer. The team also uses an observational technique known as nuclear magnetic resonance (NMR) spectroscopy to understand molecular behavior.
By monitoring the spectrum of radio waves from atomic nuclei, NMR spectroscopy gives researchers the opportunity to observe the structure and motion of those particles. Kirkpatrick has been using the technique for about 18 years to study everything from cesium contamination of soils to the products of meteor impacts to mixed-metal layered hydroxide compounds that both occur in nature and are used in drugs like antacids. Two years ago, he and Kalinichev teamed up to wed NMR spectroscopy research and molecular dyanamics computer modeling.
The spectroscopic data and computer models complement each other brilliantly. The NMR, for example, may only be able to show whether a molecule is dissolved in water or adhering to a mineral surface. The computer model, meanwhile, gives the team an exact, albeit hypothetical, representation of the arrangement of that molecule and its motion. The computer models allow the team to look at and interpret the behavior of the systems observed using NMR on a more detailed level, while the NMR data helps validate the results attained through the computer models.
"The feedback goes in both directions," says Kirkpatrick. "The relationship is incredibly symbiotic."
