Monday, January 18, 2010

Climate sensitivity, part 3

In this post, I will continue my examination of climate sensitivity using the forcing estimates published here:

In the previous post, I published a graph of total forcings versus temperature. These forcings are from multiple sources: carbon dioxide, methane, nitrous oxides, ozone, stratospheric H2O, the sun, land use, snow albedo (reflectivity), stratopspheric aerosols, black carbon, reflective aerosols and what are called 'aerosol indirect effects', which are mainly implications to do with how aerosols affect cloud formation.

It should be noted that the first three of those - carbon dioxide, methane and the nitrous oxides - are included in the GISS data as one entity called 'well-mixed greenhouse gases'.

When we examine the relationships between temperature and forcings for individual components, we find that there is only one that tracks closely the rate of temperature increases for total forcings, and that is the well-mixed greenhouse gases component.
If we combine all other forcings - the first graph above - we can see that over time these forcings have trended negative - and especially in recent times.

If we look at well-mixed greenhouse gases alone, we can see that the slope of this line is 24.137, indicating that for every full point increase in forcings from well-mixed gases the temperature increase .24137 degrees celsius.
What this indicates is that the climate sensitivity for well-mixed greenhouse gases is likely higher than the temperature increases indicate, as these increases have been suppressed by the other sources of forcing changes.

No comments:

Post a Comment