Tuesday, July 3, 2012

Climate Sensitivity Illustrations

As part of my revised Earth, Orbit and Climate presentation that I delivered at the Temecula Public Library last week, I created a sequence of illustrations showing the concept of climate sensitivity, as I understand it. These images below are not the complete sequence of climate sensitivity illustration, rather, just key points.

The first image is used to show that each doubling of CO2 produces a warming of about 1.2 degrees C. Each overlaid image doubles the CO2 on the left and the bulb level rises as the graph is drawn. Below is the final image:

Next comes the H2O feedback. I set the CO2 back to one doubling and then describe the water vapor feedback of 1.5 to 2 degrees C:

The combined CO2 and H2O are enough to change ice cover, affecting the ice-albedo feedback, shown here with a reduction of snowcover:

Then I start adding a range of feedbacks such as meltwater affecting ocean currents, CO2 fertilization and rainfall disruptions:

The final image of feedbacks is not meant to be all inclusive nor is it meant to clarify the role of each. It is meant to give the viewer an appreciation that Earth is a knot of complex, inter-related systems, each reacting to changes around it:

 And then last, I show a final climate sensitivity from the combined forcings (CO2) and feedbacks (all others), giving a final climate sensitivity of 2 to 4.5 degrees C.

Other illustrations mention that the greater uncertainty is at the high end. Then I conclude that if we double the CO2 again, we repeat this process.

As with all my projects, I welcome criticism. I hope to have my revised presentation online in a couple weeks.