For today’s post I had originally thought of doing something different, I even had an article nearly ready to show. It was going to be a discussion of a research article that I really liked more or less, somewhat starting a common theme that would continue on in this blog. However sometimes things fall into your lap and there’s not much you can do but decide to respond.
A friend of a friend sent me a .pdf yesterday and it was interesting to say the least. It was from an undergraduate university class at a university that I will keep anonymous for now. Essentially it was just lecture slides from a long-term climate change sort of class. Although the discussion began with the normal long-term drivers of climate such as geological processes, milankovich cycles and so on, it soon became apparent that the professor was slanting his slides to try and put emphasis on CO2 not being a significant driver of the climate system. For example the 800 year lag between temperature and CO2 in ice core results was pointed out, but there was no mention of the feedback role that CO2 plays on these timescales (i.e. initial orbital perturbation amplified by CO2 warming/cooling effect as oceans absorb more/less CO2). Either way, those issues are relatively miniscule in comparison to what I found at the end.
More or less what was found at the end could be considered a diatribe. An anti-climate change diatribe which was not supported by the evidence which has merit (climate sensitivity …etc…) but rather it was supported by cherry-picking and easy to debunk arguments. So that is what I am going to do today. Debunk this prof.
One of the things that stuck out to me more or less (somewhat of a nitpick) was the following slide:
Now there is nothing wrong with indicating that radiatively, water vapor is the most dominant controller of the amplitude of the greenhouse effect, however to suggest that water vapor is the greenhouse effect’s origin is disingenuous at best.
Schmidt et al (2010) actually use the previous literature and a NASA radiation model to provide an overview of each absorber’s contribution to the present day Greenhouse Effect. They find that Water Vapor contributes 50%, Clouds contribute 25%, CO2 contributes 20% and a few others make up the remaining (5%). For me I think that if a slide is going to say the Greenhouse effect is essentially water vapor, then that is dishonest because it represents only half the effect.
Schmidt et al (2010) also use the model to predict the forcing for a doubled CO2 scenario and they find that the feedbacks are positive and that extra net absorption by CO2 amplifies the water vapor and cloud forcings.
I think those points (at least regarding water vapor) are pretty well understood but Lacis et al (2010) go further to point out that “Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state” because “Water vapor and clouds are fast-acting feedback effects, and as such are controlled by the radiative forcings supplied by the noncondensing GHGs.”
These are bold statements but that is where the current thinking on the radiative effect of CO2 stand. I have decided that this will be likely a 2(or maybe 3) part series as it has taken more space than I anticipated. Part Two will look at the prof’s categorization of the relationship between the sun and current warming.