The first difficulty with climate science for the public — and this is true whether or not you believe that the climate is in trouble — is that it's so monstrously huge and long and difficult to understand.
The second difficulty is that most scientists themselves aren't very good at explaining the difficulties.
The third difficulty is that the public itself would rather think about Tiger's mistresses, or Sarah's latest outrageousness, or nearly anything but the possibility that civilization is genuinely endangered.
So let us now say a word for the plain-spoken James Hansen, the dean of climate scientists, and thank him when he clarifies climate issues, such as arguments raised his debating partner Richard Lindzen.
Lindzen has a new paper out that's getting very sharply criticized in the scientific journals (for more, see Andy Revkin's typically excellent coverage on Dot Earth). But although the criticism makes a great deal of sense, neither Lindzen's paper nor the rebuttal by Kevin Trenberth and three other scientists explains the underlying idea in a way likely to be understandable to most people.
Let me give you an example, from the opening to the 2009 paper ("On the determination of climate feedbacks from ERBE data") by Lindzen and Choi:
Climate feedbacks are estimated from fluctuations in the outgoing radiation budget form te latest version of Earth Radiation Budget Experiment (ERBE) nonscanner data. It appears, for the entire tropics, the observed outgoing radiation fluxes increase with the increase in sea surface temperatures (SSTs). The observed behavior of radiation fluxes implies negative feedback processes associated with relatively low climate sensitivity.
Okay, it's a scientific paper. Allowances must be made for the precision expected in science, and for concepts scientists know and ordinary folks have never heard of. Still, contrast that with what James Hansen says about Richard Lindzen's work in his new book, Storms of My Grandchildren:
Lindzen is convinced that nature will finds ways to cool itself, that negative feedbacks will diminish the effect of climate forcings. This notion spurred Lindzen to propose a specific mechanism for how the atmosphere takes care of itself: He suggests that columns of tropical cumulus convection intensify if carbon dioxide increases, piping energy high into the atmosphere, where the heat would be radiated into space. This mechanism, he suggests, is nature's thermostat, which keeps gobal warming at a few tenths of a degree for doubled carbon dioxide, rather than a few degrees. [pp55]
In this paper, Lindzen is focusing on sea surface temperatures, not carbon dioxide, as a forcing. But he's still convinced the top of the atmosphere is an escape hatch for global heating, and as Trenberth et al point out in a free commentary available on Real Climate, this theory has some obvious flaws.
One error is that Lindzen and Choi assume that the heat generated by sunlight on water in the tropics will remain in the tropics, which is to say, they pretend that El Niño — the best-known and most potent of climate phenomena, which can transport heat from the tropics across vast distances — doesn't exist.
The arrogance of that assumption cannot be overstated. But it can be passed over without much comment, as in Trenberth et al's phrasing:
The main changes in tropical SST and radiative fluxes at TOA are
associated with El Niño-Southern Oscillation (ENSO) and are not
necessarily indicative of forced variability in a closed system. ENSO
events cause strong and robust exchanges of energy between the ocean
and atmosphere, and tropics and subtropics. Yet LC09 treat the tropical
atmosphere as a closed and deterministic system in which variations in
clouds are driven solely by SST. In fact, the system is known to be
considerably more complex and changes in the flow of energy arise from
ocean heat exchange through evaporation, latent heat release in
precipitation, and redistribution of that heat through atmospheric
winds. These changes can be an order of magnitude larger than
variability in TOA fluxes, and their effects are teleconnected
globally. It is therefore not possible to quantify the cloud feedback
with a purely local analysis.
That's just one of their deadly criticisms. They also argue that Lindzen and Choi made fundamental — and misleading — calculating errors, to get the results they want. For more, see their discussion on RealClimate.
It's pretty shocking, but a lot easier to understand with Hansen's translation. More from him soon.
Kit Stolz 