Wood Romances

Accounting for Climate Forcings Puts ECS Near 3 °C From ClimateBrink The so-called "Climate Working Group," hired by the Department of Energy to write what Roger Pielke Jr termed a "red team" response to climate science  (my initial response is here ) is predictably critical of the central scientific estimate for ECS. The first ECS estimate I know of was calculated by Arrhenius, who concluded that 2xCO2 would cause between 4-6°C warming. This value was revised downward by Gilbert Plass in the 1950s to ~3°C, and since the 1970s this has become the standard estimate. The IPCC currently says the likely range is 2.5-4.0°C, largely as a result of Sherwood et al 2020 (S22),[1] which is still to date the most comprehensive assessment of ECS (Sherwood's likely range was 2.6-3.9°C). There is a growing body of scientific literature arguing that recent observational evidence is more consistent with an ECS closer to 4°C, suggesting that the IPCC may be a bit conservative on...

In a recent talk  (relevant excerpt from John Shewchuk  here ) given to an Australian political group called the Institute for Public Affairs (IPA), William Happer argued that doubling CO2 causes only 0.71 K warming, and that amount of warming for 2xCO2 is too small to matter. He then suggests that in order to make CO2 a problem, scientists had to invent giant feedbacks to amplify warming by as much as 10x the amount caused by CO2 alone. I've seen this claim repeated by others on X and other social media platforms, but as best I can tell Happer originates this particular argument. So I'd like to consider, is this plausible at all? I think it's pretty easy to investigate this and show conclusively that it is not. In fact, even Happer disagreed with this claim as recently as 2020. Ranges for ECS/TCR in IPCC Reports Happer's Argument At about the 1 minute mark of the above linked excerpt, Happer explains his math on how he arrives at 0.71 K for equilibrium climate sensitiv...

It's well-established physics that the Earth's surface is ~33K warmer than its effective temperature, and the relationship between increasing CO2 and radiative forcing can be approximated by the following logarithmic equation: ΔF = 5.35*ln (C/Co) where, Co is an initial concentration of CO2 (preindustrial CO2 is generally regarded as 280 ppm).  C is the concentration of CO2 at any given time (currently 420 ppm). The equation shows the change in the outgoing flux at the top of the atmosphere caused by a change in CO2 concentrations. Since CO2 concentrations have increased by 50%, we can say CO2 has caused a decrease in the outgoing flux of 5.35*ln (1.5) = 2.2 W/m^2. As a result of this decrease in outgoing flux, more energy enters the climate system than escapes into space, and so the planet's surface must warm until the outgoing flux equals incoming again. The relationship between a change in radiative forcing and temperature is linear, so ΔT = λ*ΔF So essentially the relat...

A paper is currently sitting on the ArXiv[1] awaiting publication that has garnered a fair amount of attention on social media. It's a paper by Hansen with several other well-respected and influential scientists. Since this paper is currently in prepublication, and I don't know what this paper will be like when it's published, I don't want to make too much of this, but it is very interesting, if alarming. At best, I see this as an upper bound estimate of how bad AGW could become long-term. I'd like to consider what this paper (in it's current form) is suggesting and evaluate what it claims. Summary of Hansen's Paper The general thrust of this paper is that paleoclimate evidence shows that fast feedback sensitivity (ECS) is 3.5 - 5.5°C and GHG forcings are are 4.1 W/m^2. After slow feedbacks bring the Earth's climate system into full equilibrium with these forcings (what is called Earth System Sensitivity), we can expect about 7-10°C warming long term fro...

Update (6/6/2025): I edited the text for clarity (especially in the first couple paragraphs), changed g to  g̃ to distinguish the normalized GHE from the acceleration due to gravity,  and added more references with excerpts at the bottom of the post. The Earth's effective temperature - the mean surface temperature of Earth if the atmosphere contained no GHGs but with current albedo can be calculated since we know that ASR (hereafter Fin) =  (1-α)*S/4 and OLR (hereafter Fout) is governed by  εσ*T^4. At equilibrium, ASR = OLR (Fin = Fout). With no greenhouse effect (GHE), the Earth's emission temperature (Te) would be at the surface, meaning that Te = Ts, so we can solve for Te with (1-α)*S/4 = εσ*Te^4 If we solve for Te with a surface emissivity ( ε) o f 0.98 and albedo ( α) of 0.306, we end up with Te = 255.3 K.  So, if the earth had no atmosphere with albedo roughly the same as today, the average surface temperature of the earth would be about  -18°C. ...

Little Big Econ State Forest (just because it's pretty) Any given climate forcing affects the Earth's Energy Imbalance (EEI) - that is, it affects the amount of energy entering the climate system vs energy escaping into space. When a forcing occurs, such as from an increase in CO2, the imbalance is created and surface temperature increases until EEI returns to equilibrium (that is, EEI = 0). But how long does this take? That is, what is the lag between a climate forcing and the new equilibrium temperature? It turns out, this depends on sensitivity and the rate of temperature increase, but it is possible estimate the time to achieve this equilibrium with a forcing. But this is going to be rather math-intensive. Apologies in advance! We can begin with a simple energy balance equation: (1) ΔF = ΔT/ λ  + EEI, where λ is sensitivity (ECS/F2x) ECS is Equilibrium Climate Sensitivity F2x is the forcing for doubling CO2 EEI is the Earth's Energy Imbalance ΔF is the change in radiati...