Varavut Limpasuvan, professor of applied physics at Coastal Carolina University, will discuss “Diagnosing the Beating Heart of Our Atmosphere: A Puzzle for Future Generations” at 7:30 Thursday in the Wall Auditorium on campus. He is the 14th recipient of the Distinguished Teacher Scholar Lecturer Award presented by Horry Telephone Cooperative. Limpasuvan earned a doctorate in atmospheric sciences from the
Below is the other part of my Q&A with him. (The other part ran in today's The Sun News paper edition.)
Bailey: Is it accurate to say we have solid evidence that Earth has been warming and that man has been contributing, on some level, to that warming?
Limpasuvan: The evidence for warming is there. Measurements of surface temperature and more recently air temperature from satellite (accounting for stratospheric effects) indicate a clear warming trend. In the past decade, this warming trend has declined slightly due to a 10 percent drop in water vapor concentration (an important greenhouse gas) in the stratosphere. The decline in the stratospheric water vapor and it relates to warming is still unclear. The role of human contribution to the warming trend is also suggested. If we examine the carbon dioxide (CO2) amount that dates back a few hundreds of thousands of years from the present (inferred, for example, from ice cores in Antarctica), we see that, while CO2 concentration fluctuated in time, the largest CO2 amount never got above 300 parts per million by volume (ppmv). Within the last 200 years or so, CO2 was already around 270 ppmv at the start of the Industrial Revolution. Today, that amount is heading toward 400 ppm. The greenhouse effect due to CO2 is well established. The added CO2 would contribute to the overall warming of the earth's lower atmosphere. So, there is a circumstantial evidence relating the warming trend to the CO2 increase and human activity. However, we need to note that there are other variables in the climate system (e.g. ice, water vapor, clouds, and biology) that offer competing effects that can amplify or attenuate this warming effect, attributable to CO2. So, how much does the doubling in CO2 translates to the actual (observed) warming is debatable.
Bailey: Is the science related to global climate change settled?
Limpasuvan: No, I don't think the issue of “global climate change” is settled. The climate system is so complex. As noted previously, there are so many components to the climate that can amplify or attenuate anthropogenically or naturally induced perturbations. We still don't have enough reliable long-term data to formulate a complete understanding of the climate system. Global observations (like satellite) really just started in the 1970's. Past observations were very localized and/or based on proxies. Measurements that we have are always going to be subjected to biases/errors based on the employed techniques, calibrations, and, more important, how we interpret the observations. We still need to improve climate models or other ways to assess changes. We need to have a better understanding of the natural variability that persists in the climate system.
Bailey: What are your general thoughts about “climate change,” i.e. “global warming?”
Limpasuvan: The global climate has always been changing since the formation of earth. Only recently, in terms of earth's history, are we starting to realize the potential role that we may have on its evolution. Global climate change is one of the few topics in which we cannot be an independent observer to study the problem since we are completely immersed in and interacting with the various climate components, e.g. the atmosphere and the ocean. That is, we too are part of the climate system. As such, I think “global climate change” is a very challenging problem. How we address the problem will have potentially large impacts on future generations.
