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What is my stance on climate change? Well, I'll lay it out for all of you newcomers. Grab some popcorn! 🍿 First, I do not deny the fact that the Earth has warmed up by ~1.2°C since 1850. However, nobody knows precisely how much because of data quality issues (e.g., uneven surface station distribution; fragmented records, especially outside of the United States; station siting changes; and urban heat island contamination) that have not been (and likely cannot be) removed from the record. But, I have no doubt that the Earth is [slightly] warmer than it was 175 years ago or that 𝑠𝑜𝑚𝑒 of that warming might be due to carbon dioxide (CO₂) emissions. Second, contrary to what the online army of alarmist foot soldiers have 𝑚𝑖𝑠𝑙𝑒𝑑 people to believe, there are not really any so-called “fingerprints” that distinguish human-caused global warming from warming caused by other forcings / variability. Numerous scientific papers claim to have found such a “fingerprint,” but the only evidence that they have presented is that the anomaly of interest is 𝑐𝑜𝑛𝑠𝑖𝑠𝑡𝑒𝑛𝑡 𝑤𝑖𝑡ℎ anthropogenic warming. But these authors fail to mention that said anomaly would also be consistent with natural warming. Case in point, a reduction in low- and mid-altitude stratiform cloud cover, for instance, would allow more sunlight into the climate system, which would warm the oceans. A warmer ocean—all else being equal—increases the rate of evaporation, which raises the vapor pressure (humidity) contributing to polar amplification and faster land warming than the ocean (e.g., Compo & Sardeshmukh, 2008). 🔗https://t.co/sQurHsN80P / open-access: https://t.co/WVKvLrSV7k All warming, natural or man-made, results in: 1⃣ Higher latitudes warming faster than both the mid-latitudes and tropics. 2⃣ Land heating up faster than the oceans. This is just basic physics; look up heat capacity. Also, an increase in, say, solar forcing would have the same material effect, though we can admittedly likely rule that out as the cause of modern trends because sunspot activity has been declining in recent decades. But the sun does affect our climate in ways that have not really been thoroughly researched because little, if any funding, is ever allocated for such projects by the funding agencies such as the National Science Foundation (NSF). In any case, the 𝒃𝒆𝒔𝒕 empirical evidence that I have seen to suggest that there is probably [at least some] anthropogenic “fingerprint” on recent temperature increases is stratospheric cooling. First, you need to understand that in atmospheric physics, heat flux is measured as power—measured in Watts (that is, Joules per second)—standardized per square meter of surface area. This is written as W/m². Next, the average radiation flux into the atmosphere is on the order of 239 ± 3.3 W/m² of absorbed solar radiation (ASR) averaged over a year (Stephens et al., 2012). This means that in order for the Earth's surface to maintain a constant temperature, the surface must emit 239.7 ± 3.3 W/m² back to outer space. 🔗https://t.co/5z5iMdazRB / open-access: https://t.co/51Ys5w8BWj Global warming theory maintains the direct radiative forcing from doubling atmospheric CO₂ levels (often noted as RF 2×CO₂) is 3.7 ± 0.4 W/m² (e.g., IPCC TAR, 2007). That means that the net outgoing longwave radiation (OLR) to outer space is reduced by 3.7 W/m², which creates an Earth energy imbalance (EEI), which leads to a slight warming tendency in the troposphere (surface to ~13 km altitude). 🔗https://t.co/0JkXIQRGDH (p. 357) In the stratosphere (~13-50 km altitude), this causes a cooling tendency because less infrared radiation (IR) flux is moving upward from below. These relationships were first demonstrated in Manabe & Strickler (1964). 🔗https://t.co/JNaXP7nUC9 NASA satellite measurements indicate that cooling in the stratosphere has been observed since the late 1970s, although there has been very little cooling over the last 25 years, all the while the troposphere has continued to warm. 🔗https://t.co/hT0Oxwm2Io That means that most of the warming observed since 2000 is likely natural OR perhaps partly caused by a reduction in stratospheric sulfate aerosol concentrations, an artifact of particulate aerosol pollution regulations in recent years. But, yes, I would agree with most scientists that the cooling observed in the stratosphere, at least that from the 1970s to 2000, is most likely a result of CO₂ forcing. So what? What happens down here in the lower atmosphere in response to CO₂ forcing is a lot more nuanced. Why? Because here in the troposphere, there are feedbacks (largely cloud-related) and precipitation processes that affect the atmospheric radiation budget far more than CO₂. And how exactly clouds respond to warming in the troposphere, if at all, is not very well understood, and by extension, not well-modeled. What we do know, theoretically speaking, is that the direct warming effect of RF 2×CO₂ is actually very small. Specifically, it is on the order of ~1°C (e.g., Wijngaarden & Happer, 2020). 🔗https://t.co/y5szlGBmjd However, amplifying (or dampening) feedbacks that kick in as a response to radiative forcing mean that the real-world value—that is, the equilibrium climate sensitivity (ECS)—will be higher (lower) than the ~1°C figure derived from radiative transfer calculations. So, three critical pieces information are unknown: 1⃣ Exactly how much warming has been man-made (since, let's say, 1950). We still don't know the answer to this because the coefficients that are used to ascribe anthropogenic versus natural forcings are all estimated from computer modeling, not real physical in-situ measurements. 2⃣ The exact value of ECS. 3⃣ Even if global warming is entirely man-made, is it really a net drawback to civilization? Is it a crisis? Is it a problem in the slightest? To break it down: • If ECS is <3°C, the climate is insensitive to GHGs, and impacts are exaggerated. • If ECS is ≥3°C, the climate is sensitive to GHGs, and warming could be a concern. The IPCC’s “best estimate” of ECS is 3°C with a range of 2-5°C. 🔗https://t.co/8Ntgszr1dC (pp. 44-45) In 1994, using NASA's real-world bulk atmospheric temperature data, one of my mentors, Dr. John Christy and his co-worker, Dr. Richard McNider from the University of Alabama in Huntsville (UAH), calculated climate sensitivity by removing the effects of El Niño / La Niña and volcanic stratospheric aerosol injection (e.g., El Chichón, 1982; Mt. Pinatubo, 1991). Christy and McNider found that the human-induced warming rate is about 0.09°C / decade (lower than observations of actual temperature increase). This, by the way, came with the stipulation that unknown mechanisms of internal variability or external forcing are assumed to be zero. I attended a lecture where he talked about this paper in detail. 🔗https://t.co/S2GEmUftKo They then validated their 1994 findings in McNider & Christy (2017). Specifically, they found a near-identical anthropogenic warming rate of only 0.096°C / decade and a transient climate response (TCR) of 1.10 ± 0.26°K. 🔗https://t.co/zueJLn8V8w / open-access: https://t.co/eLcqeizbRh Many other recent studies (e.g., Lewis & Curry, 2018; Scafetta, 2021; Spencer & Christy, 2023; Lewis, 2025) have all estimated ECS to be far lower than the IPCC AR6's “best estimate.” 🔗https://t.co/8G0sF8gy2p 🔗https://t.co/5TgNX7c1JN 🔗https://t.co/BxyO1XIbNP 🔗https://t.co/YNQhNajrrO The jury on ECS is still out. 🤷‍♂️ What's more, in order to reliably detect anthropogenic influence on the climate system, EEI must be known to the nearest 0.1 W/m² (Von Schuckmann et al., 2016; Gebbie, 2021). 🔗https://t.co/T7SKxidZ4N / open-access: https://t.co/GD45cbhxIT 🔗https://t.co/L6vZKVVpXg However, the aforementioned Stephens et al. (2012) estimates the EEI to be 0.6 ± 0.4 W/m², which is eight times larger than the anthropogenic detection limits. And the natural top-of-atmosphere (TOA) flux has a 6.6 W/m² margin of error, which is 66 times larger than the detection limits. This range of uncertainty remains in newer estimates, such as Loeb et al. (2021), which estimates EEI to be 1.12 ± 0.48 W/m². 🔗https://t.co/ynRTFd3LWZ This means that 𝑚𝑜𝑠𝑡 (but not all!) of the observed global warming since 1950 could be natural and scientists would never know for certain (nor would most be humble enough to admit it because the vast majority of academics have high egos). Alternatively, warming could be mostly man-made like alarmists claim, but, even if that is the case, I'll ask again. . . SO WHAT? That doesn't mean it is an existential crisis or urgent problem. The big unknown are CLOUDS. ☁️ Why? Because (a) cloud albedo has a far greater impact on the atmospheric radiation budget than does CO₂, and (b) how clouds change in response, if at all, to CO₂ is unknown. What's more, cloud cover can (and does) change naturally without mankind's assistance for any number of reasons (e.g., El Niño / La Niña activity; ocean circulation changes; cosmic ray flux; etc.). Even a small decrease in global cloud area fraction (CAF) can more than offset any temperature rise caused by CO₂. Song et al. (2016), for instance, found that, 🗨️ “[����]𝑙𝑡ℎ𝑜𝑢𝑔ℎ 𝑡ℎ𝑒 𝑔𝑟𝑒𝑒𝑛ℎ𝑜𝑢𝑠𝑒 𝑒𝑓𝑓𝑒𝑐𝑡 𝑐𝑎𝑛 𝑏𝑒 𝑒𝑛ℎ𝑎𝑛𝑐𝑒𝑑 𝑏𝑦 𝑖𝑛𝑐𝑟𝑒𝑎𝑠𝑖𝑛𝑔 𝐺𝐻𝐺𝑠 𝑎𝑛�� 𝑤𝑎𝑡𝑒𝑟 𝑣𝑎𝑝𝑜𝑟 𝑖𝑛 𝑡ℎ𝑒 𝑎𝑡𝑚𝑜𝑠𝑝ℎ𝑒𝑟𝑒, 𝑖𝑡 𝑐𝑎𝑛 𝑏𝑒 𝑤𝑒𝑎𝑘𝑒𝑛𝑒𝑑 𝑏𝑦 𝑑𝑒𝑐𝑟𝑒𝑎𝑠𝑖𝑛𝑔 𝑐𝑙𝑜𝑢𝑑𝑠. 𝐼𝑓 𝑡ℎ𝑒𝑠𝑒 𝑡𝑤𝑜 𝑎𝑐𝑡𝑖𝑜𝑛𝑠 𝑜𝑓𝑓𝑠𝑒𝑡 𝑒𝑎𝑐ℎ 𝑜𝑡ℎ𝑒𝑟, 𝑎 ℎ𝑖𝑎𝑡𝑢𝑠 𝑜𝑓 𝑡ℎ𝑒 𝑔𝑙𝑜𝑏𝑎𝑙 𝑔𝑟𝑒𝑒𝑛ℎ𝑜𝑢𝑠𝑒 𝑒𝑓𝑓𝑒𝑐𝑡 𝑤𝑖𝑙𝑙 𝑟𝑒𝑠𝑢𝑙𝑡.” 🔗https://t.co/NHkmfOc08y I don't deny that global warming is occurring. I never have. I don't even deny an anthropogenic influence on it either. I never have. What I do reject, however, is unchecked alarmism and climate activism, particularly from fellow scientists. Activism is not science and has no place in science. If you are an activist, you cannot call yourself a scientist because you are not dispassionate and objective. This goes for the vast majority of self-described “climate scientists” who actively use social media and are well-known in the debate. Two notable exceptions on the other side of the spectrum from me, in my opinion, are Drs. Robert Rohde and Paul Williams, both of whom I have always had pleasant interactions with. I also reject the idea that every weather event needs to be blamed on climate change with a rushed, half-baked attribution study (namely the ones done by the clowns at World Weather Attribution that are often not scientifically rigorous, but get plenty of news media attention by the Associated Press, CNN, The New York Times, and The Washington Post). Attribution “science” is fraudulent anyway because one of the architects behind it admitted to Politico in 2021 that it was designed with the intention of using it in litigation against oil and gas companies. 🔗https://t.co/ETUBune0A8 Conflict of interest much? It should also be abundantly clear that climate is just a statistical description of the mean and variability of the climate system, including long-term weather. So, a change in climate is just a change in statistics. That is an outcome, not a force or accelerant that causes an extreme weather event to occur. For what it's worth, I used to be a climate alarmist well before I got my degree in meteorology. Now that I know a great deal (but not everything and never will) about atmospheric science, my position has evolved to a cooler heads point of view. Perhaps it is not my judgement that's clouded, but rather that of the alarmist arm-wavers who have high trust in both academic institutions and their government officials who spoon-feed them pre-canned talking points on the daily.