As humankind adds carbon dioxide, aerosol particles, and other nasty things to the atmosphere, we can expect our climate to change over the 21st Century, but it's not easy to predict how fast the climate should change and how it will change in different parts of the world. One big uncertainty is just how sensitive our climate is to external influences. We know how much a given amount of carbon dioxide will warm the atmosphere, but that warming sets into motion a variety of changes in the Earth system that can either exacerbate or mitigate the original warming. We don't understand these internal feedback processes very well, largely because we don't understand the details of how different meteorological phenomena conspire to change the amount, phase, and spatial distribution of water in the atmosphere. Will a warmer climate be more humid or drier? Have cloudier or clearer skies? Will storms be more or less frequent, stronger or weaker? Depending on the answers to these questions, long-term climate change may be a more pressing or lower priority societal concern.
I use satellite and surface-based observations of the current climate to understand the processes that regulate changes in water vapor and clouds. Some of these observed changes are relevant to how the same processes will change as we add greenhouse gases to the atmosphere and thus give us clues as to how climate change may play out. With this information, I examine global climate model predictions of future climate to see whether the models change in what seem to be realistic ways. If they don't, I try to use the observations to figure out what physical processes are missing in the global model and how to represent those processes as realistically as possible, with the goal of gradually increasing our confidence in the model's predictions of the future. I also occasionally study storms on other planets such as Jupiter, Saturn and Titan to gain a more fundamental understanding of how their meteorology differs from that of Earth.