NASA obviously is very focused on what we can see from space, what we can learn from space about our own planet. And so we have a lot of satellites in orbit that are producing huge amounts of data that are telling us about how the clouds are changing, how the sea surface temperatures are changing, what's going on with ozone, what's going with aerosols, and all of these things are giving us a unique view of the planet as it is right now.

The role of models is to integrate that information, to synthesize that information with what we know about physics, what we know about sources of aerosols, what we know about atmospheric chemistry, what we know about ocean dynamics, and then build a picture that allows us to go from the information that we're seeing from the satellite to infer things that about what we think about the whole planet, how it's changing.

Modelers don't actually have a crystal ball. There are many, many things that are going to happen in the future that we can't predict. There's going to depend on economic development, technological development, societal development, all of those things are completely outside of the ken of a climate modeler like myself.

So what we can do instead is we can do scenarios, we can ask 'what if' questions. What if we continue to increase the amount of carbon dioxide in the atmosphere? What if we continue to increase the amount of tropical deforestation? What if we continue to increase the amount of air pollution from Asia and from the rest of the world? And we can say, ok, well if those things happen, then these are likely to be the climatic effects. These are likely the changes in temperatures, the changes in statistics of heat waves, in rainfall patterns, and in rainfall intensity. And we try to put those together and test them with observations that we've had over the past when we've got good information from the satellite record, and even going further back where we have information from proxy records that allow us to test our model system, that we understand what the major drivers and the effects are.