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Showing posts with the label greenhouse effect

A New Paper Makes Low Sensitivity Models More Implausible

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A paper was published this week that argues that low-sensitivity models do a poor job of reproducing CERES-derived EEI trends. In the words of the paper, the authors used CMIP6 models "to illustrate that low climate sensitivity models have an EEI trend behavior that is inconsistent with the satellite-derived EEI trend." Even though models with an ECS near 3°C do a good job of reproducing current warming, CMIP6 models often differ in the in EEI trends. For instance, The CERES data show a stronger trend in EEI than the multi-model CMIP6 mean and higher EEI in 2023 than any of the CMIP6 models. However, for individual CMIP6 models and ensembles, EEI is comparable to or higher at other periods than the CERES value in 2023. The difference in trends can be seen by comparing the red CERES line to the black CMIP6 model mean. Even though the interannual variability in the CMIP6 models is consistent CERES observations, the observed trend in EEI, especially since about 2010, is higher t...

A Simple Test of Nikolov's Alternative to Greenhouse Gases

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This is a follow up to a post about Nikolov & Zeller here , updated on 4/14/2025. In a recent manuscript [1] "published" on the so-called Science of Climate Change blog, Nikolov and Zeller (NZ) articulate how they believe that the Earth's temperature remains warmer than its effective temperature. Without getting into whether that amount should be considered 90K or 33K, it's clear that for them the long-term baseline temperature of earth is determined solely by total solar irradiance (TSI) and atmospheric pressure (P). Here it is in their words: NASA planetary data indicate that the radiative “greenhouse effect” does not exist in reality. That’s because, across a wide range of planetary environments in the Solar System, the long-term (baseline) global surface temperature on rocky planets and moons is fully determined by the mean Total Solar Irradiance (i.e. distance from the Sun) and total surface atmospheric pressure. Variability on this long-term baseline temper...

Stefani's Paper Illustrates the Failure of MDPI Peer Review

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A recent paper[1] published in the MDPI journal Climate by Frank Stefani provides a wonderful illustration of why we should never treat papers from MDPI journals as having any competent, let alone robust peer review. This paper argues that TCR = 1.1°C (0.6°C - 1.6°C) for doubling CO2. I'm not going to evaluate the entire paper here, since that would take too much time. The paper does make some counterfactual claims, like there's a "nearly perfect correlation of solar activity with temperatures over about 150 years." That's objectively false, but the correlation between CO2 forcings and GMST has an r^2 = 0.88. There's also some comical contrarian alarmism in this paper: "we fear that the huge Milankovitch drivers will—perhaps much too soon—massively interfere with the solar and anthropogenic factors that were considered in this paper." There's a lot we could say about this paper, but I want to focus here on some elementary math errors that would ...

Does Climate Science Assume the The Earth is Flat?

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On Facebook I recently came across a character by the name of Joseph Postma. I had come across some of his ideas on YouTube in the past and had quite a laugh at some of the nonsense that he puts in his videos, but recently Postma started participating in a group that I participate in, so I've interacted with him personally. For those of you unfamiliar with him, his ideas should best be understood as coming from the lunatic fringe of contrarian thinking. In fact, I'm seriously tempted to think that he doesn't actually believe what he says, but he's basically seeing how absurd he can be and still get people to believe him. To be sure, he has not yet convinced even the most radical of people blogging on some of the most popular contrarian sites. I mean, WUWT has posted criticisms of his views, Willis Eschenbach has publicly disagreed with him, and Roy Spencer has devoted at least one post  to responding to his claims. Even David Burton has taken issue with Postma. In othe...

Can Atmospheric Pressure or Density Explain the Earth's Temperature?

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In my last post , I responded to the claim that the greenhouse effect contradicts the second law of thermodynamics. When people make this claim, I often ask what it is that makes the Earth's temperature warmer than its effective temperature if there's no greenhouse effect. The response I get back usually has to do with what can only be described as an ill-informed, "crackpot" theory arguing that this is due to atmospheric pressure or density. Using the ideal gas law, critics of science calculate the temperatures on planets like Venus, Earth and Mars from other known quantities in the ideal gas law, and then assert that this means planetary temperature is due to density or pressure instead of GHGs. There are multiple versions of this, all of which claim either that there is no greenhouse effect or that the greenhouse effect has nothing to do with greenhouse gases and everything to do with atmospheric pressure and/or density. To my knowledge the original version of this...

Does the Greenhouse Effect Contradict the 2nd Law of Thermodynamics?

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Occasionally I hear people claim that the greenhouse effect isn't real because it would contradict the 2nd law of thermodynamics. The idea behind this is that the atmosphere is cooler than the Earth's surface, and the 2nd law of thermodynamics says that heat always goes from hot to cold. Therefore, the Earth's atmosphere can't heat the Earth's surface. Therefore, the greenhouse effect can't exist in a universe in which the 2nd law of thermodynamics is operable. A Simple Explanation The silliness of this objection can become apparent with a simple analogy. If you walk outside with a thin t-shirt on a cold day (let's say 20°F), you'll quickly feel cold, and the surface of your skin will be significantly colder than normal. If you find a winter coat outside, its temperature will be 20°F. But if you put it on, you will begin to warm. It's not that the coat is generating heat and sending it to your body. It's simply slowing down the rate at which ther...

Is CO2 Saturated in the Atmosphere?

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A very common objection to climate science goes something like this - CO2 already absorbs all the IR radiation it can possibly absorb, so the greenhouse effect is saturated and adding more CO2 will not cause any more warming. Sometimes this objection is accompanied by an analogy. If you apply translucent tape to a clear window, you obstruct some but not all light passing through the window, but the more tape you add, the more lite is obstructed, and eventually you reach a thickness of tape beyond which no light can pass through. The tape has made the window opaque, and so adding more tape can't do anything more. Of course, if this were true, and if we are either at or near that saturation point, there would be no need to stop emitting carbon, since any additional carbon we add to the atmosphere won't change the Earth's temperature (it would continue to cause ocean acidification, though, but let's leave that for another day). The reasoning behind this objection is flawed...

Observational Evidence for the Greenhouse Effect

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In a previous post I looked at evidence of the greenhouse effect from empirical data. In short, an analysis of empirical data for CO2 and GMST shows a one-way causation with CO2 causing warming since the mid-twentieth century. This paper conclusively establishes causation from empirical time series of CO2 and temperature. That is, not only is CO2 a good predictor of temperature, but  uncertainty is reduced in future values of temperature given past values of CO2. This evidence is conclusive, but  even without this, we have observational evidence for the greenhouse effect. In this post I want to consider how this is true generally in satellite observations of earth's emission spectrum at the top of the atmosphere and in individual studies that have made observational determinations of the greenhouse effect. General Observations The graph above quite literally shows the greenhouse effect. This can be readily determined, but we need to begin by calculating the effective temperat...

How Do We Know that Increasing CO2 Causes Warming?

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This is part 1 of a two part post. The evidence that increasing CO2 causes air temperature to warm began to accumulate as far back as the 1850s with studies from William Tyndal l[1][2] in the UK. Tyndall's experiment can be roughly replicated in high school lab classrooms with pretty simple experiments, some of which are demonstrated on YouTube. Estimates of climate sensitivity to increasing CO2 can be found in the works of Arrhenius[4] in the 1890s and Plass in the 1950s.[5] The landmark work of Manabe in 1967 successfully modeled the effects of increasing CO2 on the climate system. His study produced theoretical predictions that have been observed ever since. Especially since the satellite era, for instance, scientists have observed that the stratosphere is cooling while the troposphere is warming, just as Manabe expected. In the 1970s, scientists arrived at an estimate of equilibrium climate sensitivity[7] of about 3 C; an estimate that still continues to be at the center of sc...