Andy May and Marcel Crocker
An anonymous reviewer commented on our recent paper “CO2 and a warming climate is not a problem,” published online on May 29, 2024, American Journal of Economics and Sociology.
In the introduction to his critique, Phytophthora destructor writes: “The authors and the sources they cite may have underestimated anthropogenic global warming. We have no estimate of the anthropogenic contribution to global warming.” All we have done is point out that if some of the observed warming is a natural phenomenon, then the IPCC AR6 estimates of anthropogenic global warming would be too high. This is indeed true.
The first part of the main criticism is actually a lengthy critique of Harvey Vinos's book Past, present and future climatewhich is not relevant to our paper. His criticism compared Vinos' predictions for the future to those of the IPCC, none of which our paper makes. We are only discussing the climate of today and the recent past (going back to 1750), so this part of the criticism is not relevant to our paper and should be directed at Dr. Vinós.
Although we cite some published predictions in our conclusion, we deliberately avoid making any predictions ourselves and our paper considers only past and present observations. The criticism cast doubt on Vinos' predictions of the future, claiming the IPCC's predictions were based on the impact of carbon dioxide2 Emissions, to be more precise. We don't know yet whether Vinos or the IPCC's predictions are correct, as the time for discussion has not yet ended. Our paper discusses present-day and past climate conditions, and projections of the future are not observations and should not be confused with them.
The next section attempts to question the existence of all multidecadal ocean oscillations based on two papers by Michael Mann and co-author Mann et al. (2020) and Mann et al. (2021). Mann's 2020 paper attempted to show that the most cited ocean climate oscillations, AMO and PDO, are not statistically significant because their signals are not high enough to rise above the red noise. However, he admitted, historical The AMO observations are statistically significant, and only the climate model results are not statistically significant. Since all models are wrong (Box, 1976), this argument is rather weak.
PDO is often interpreted as a long-term change in the La Niña/El Niño ratio, and (Mann, Steinman, & Miller, 2020) do acknowledge that this ratio changes in a statistically significant way on a 40-50 year time scale. He simply questions the predictability of traditional PDO.
We acknowledge that long-term ocean oscillations are poorly understood and poorly described. However, Mann et al. (2020) provided no valid evidence that they do not exist or have natural ingredients. In fact, he admitted:
“Based on available observational and modeling evidence, the most plausible explanation for the multi-decade peak seen in modern climate observations is that it reflects responses to a combination of natural and anthropogenic forcings over historical periods.” (Mann, Steinman, and Miller, 2020)
We agree with this statement and it is consistent with our paper.
Mann et al. (2021) attempted to explain multidecadal ocean oscillations (particularly the AMO and PDO) as artifacts of volcanic activity and anthropogenic greenhouse gases and aerosols. Likewise, as noted in Mann (2020), Mann (2021) noted the lack of a multi-decade signal in climate model simulations but acknowledged that the signal can be seen in observations (Mann M., Steinman, Brouillette, & Miller, 2021) . We believe that if the signal is seen in observations and paleoclimate proxy data but not in climate models, then this is a reason to distrust the climate models rather than a reason to reject the proposed natural oscillations.
We do believe that anthropogenic greenhouse gases and aerosols, as well as volcanic activity, have some influence on climate, but we believe that the current warming is “exacerbated” by natural ocean oscillations. These oscillations have been observed in nature and date back to 1567 AD, long before anthropogenic greenhouse gases and aerosols could be a factor in climate change (Gray, Graumlich, Betancourt, & Pederson, 2004).
The evidence presented by Mann (2021) that volcanic activity causes “significant” ocean oscillations is based on patterns, not observations. There are many reasons for this problem, the most important of which is that the IPCC AR6 model does not reproduce critical tropical sea surface temperatures (SST) well, even though SST is a key component of most ocean oscillations. From AR6:
“We assess with moderate confidence that CMIP5 and CMIP6 models continue to overestimate the observed warming in the tropical upper troposphere during 1979-2014 by at least 0.1°C per decade, in part by overestimating tropical SST trends during this period. Mode. AR6, page 444
“…despite decades of model development, improvements in model resolution, and advances in parameterization schemes, there is still no systematic convergence in model estimates of ECS. In fact, the overall inter-model distribution in ECS for CMIP6 Larger than CMIP5; …” AR6, WGI, page 1008.
In other words, both AR5 and AR6 climate models overestimate sea surface temperatures in the tropics, which cover almost half of the Earth's surface. Additionally, model estimates of ECS (Equilibrium Climate Sensitivity to a Doubling of CO22) is worse in AR6 than in AR5, suggesting that the model is getting worse, not better, over time relative to observations (see also here). Other studies have also shown that climate models are ineffective compared to observations (McKitrick & Christy, 2020) and (McKitrick & Christy, 2018). Model evidence cannot be used to prove that observational evidence is incorrect.
Anonymous critics of our paper then compared the predictions of Vinós (Wyatt & Curry, 2014) and others with those of the IPCC again. We are not making any predictions, we are simply citing observations. The deadline for the various predictions they criticize has not yet arrived, so which predictions, if any, prove to be correct is unknown and will not be known for decades to come. Debating which prediction is correct is currently a fool's errand. Forecasts are an important part of science, but one should wait until the forecast period is over before criticizing them.
discuss
This criticism is typical of everything that is wrong with modern climate science. Phytophthora destructor builds on the apparent straw from the articles we cite, which have nothing to do with our argument that observations show no danger or net harm from climate change today, and then attacks his own straw, not our thesis. Unfortunately, this irrelevant straw man fallacy is common in climate science and is never credible.
Even well-trained climate scientists often conflate climate model results with observations as if they are of equal importance or importance, but this is not the case. The following statement by Mann et al., 2021 is patently incorrect:
“Our analysis reveals the presence of a strong multi-decadal, narrowband (50 to 70 year) oscillating 'AMO-like' signal in simulations over the past millennium; this oscillation is caused by high-intensity explosive volcanoes that have occurred over the past few centuries. driven by activity, showing multidecadal rhythms. Despite persistent claims that proxy data reveal such a signal, we found no evidence of internally generated multidecadal oscillation signals (Mann, M. Steinman, Brouillette, & Miller, 2021)
In other words, our simulations show that volcanism caused the oscillations, and proxy evidence that the oscillations are natural is wrong because our model says so. This is obviously flawed logic; however we do agree that current ocean oscillations may also have forcing (CO2 and volcanism) and unforced (natural) components. But as Mann (2020) states, objectively separating these two components is problematic.
Like all models, climate models are always wrong (Box, 1976). If done properly, the observations will always be correct within the accuracy of the measurement. Ocean oscillations, such as AMO, PDO, etc., are observed climate features. They are real and cannot be refuted by climate model results.
Note: Neither Marcel nor Andy has a PhD, so Phoma destructiva uses the title “Ph.D.” Wrongly.
Box, G. E. (1976). Science and statistics. Journal of the American Statistical Association, 71(356), 791-799. Retrieved from http://www-sop.inria.fr/members/Ian.Jermyn/philosophy/writings/Boxonmaths.pdf
Gray, ST, Graumlich, LJ, Betancourt, JL, & Pederson, GT (2004). Reconstruction of multidecadal Atlantic oscillations since AD 1567 based on tree rings Geophysics. resource. Express, 31. No.: 10.1029/2004GL019932
Intergovernmental Panel on Climate Change. (2021). 2021 Climate Change: Physical Science Foundations. In V. Masson-Delmotte, P. Zhai, A. Pirani, SL Connors, C. Péan, S. Berger. . . B. Zhou (Editor), Working Group 1. Retrieved from https://www.ipcc.ch/report/ar6/wg1/
Mann, M., Steinman, B., & Miller, S. (2020). Internal decadal and decadal oscillations are lacking in climate model simulations. Nature Communications, 11. doi:10.1038/s41467-019-13823-w
Mann, M., Steinman, B., Brouillette, D., & Miller, S. (2021). Multidecadal climate oscillations driven by volcanic forcing over the past millennium. Science, 3171014-1019. doi:10.1126/science.abc5810
McKitrick, R., & Christy, J. (July 6, 2018). Tests of tropical 200 to 300 hPa warming rates in climate models, Earth and space sciences. Earth and Space Sciences, 5(9), 529-536. Number: 10.1029/2018EA000401
McKittrick, R., & Christie, J. (2020). CMIP6 Common warming biases in the troposphere. Earth and Space Sciences, 7. Number: 10.1029/2020EA001281
Wyatt, M., & Curry, J. (2014, May). The role of Eurasian Arctic shelf sea ice in long-term changing hemispheric climate signals during the 20th century. climate dynamics, 42(9-10), 2763-2782. Retrieved from https://link.springer.com/article/10.1007/s00382-013-1950-2#page-1
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