Wood Romances

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...

The popular contrarian blog No Trick Zone has made a name for itself for compiling lists of papers that are claimed to demonstrate that some aspect of climate science is all wrong. The papers in these lists generally fall into a few categories: Papers published in junk (pay-to-play) or predatory journals. Papers published in legitimate journals that don't say what NTZ claims they say. Papers published in legitimate journals that do in fact challenge some aspect of AGW. Studies show that papers in the third category total less than 1% of the recent peer-reviewed literature, so you have to wade through a ton of papers in the first two categories to find the one(s) that belong in the third. It used to be when people promoted these NTZ blogposts on social media, I'd go through the trouble of looking up the papers to confirm that the general principle I describe above still holds true. I no longer waste my time with that (Brandolini's Law and all), but occasionally WUWT picks u...

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...

Cenozoic CO2 and Temperature A new paper was published this month that I think will produce some exciting new insights for those interested in historical geology and paleoclimate studies. The paper is a product of the Cenozoic Carbon dioxide Proxy Integration Project (CenCO2PIP) Consortium, and it looks to reconstruct the proxy evidence for CO2 levels during the Cenozoic (the last 66 million years). The Cenozoic began after the asteroid impact (and/or volcanism) at the Cretaceous-Tertiary (K-T) boundary that caused the mass-extinction that included the extinction of non-avian dinosaurs. The value of this kind of work will have significant benefits for scientists as they seek to constrain estimates for long-term climate sensitivity (ESS). We can think of "sensitivity" on roughly three time scales:  TCR : On a near-immediate time scale, GMST increases with increasing CO2 in what is called transient climatic response (TCR), which generally speaking tells you how quickly temperat...

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. ...

In a previous post , I calculated ECS (accounting for increases in GHGs and aerosols) to be about 3.3 C.  The calculation was based on CO2 causing 2.11 W/m^2 increase in radiative forcing with a total increase, after accounting for GHGs other than CO2 and aerosols, of 2.17 W/m^2 (aerosols cancel out most of the effects of GHGs outside of CO2). One weakness of that approach is that it used a value for EEI that was an average for 2011-2018 with forcings that were current through 2020. I've been thinking about a way to improve this, and here's what I came up with. Transient Climate Response (TCR) Since the relationship between CO2 and temperature is logarithmic, I decided to plot the relationship between temperature and ln(rCO2) to see what that might be able to tell us about sensitivity from empirical data. So in the above graph, on the y-axis I plotted GMST from HadCRUT5 using a 1850-1900 baseline to match the IPCC's approximation of preindustrial levels. On the x-axis, I pl...