{"id":280164,"date":"2023-09-24T13:37:43","date_gmt":"2023-09-24T11:37:43","guid":{"rendered":"https:\/\/climatescience.press\/?p=280164"},"modified":"2023-09-24T13:37:46","modified_gmt":"2023-09-24T11:37:46","slug":"more-on-the-statistical-dispute-between-scafetta-and-schmidt","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=280164","title":{"rendered":"More on the statistical dispute between Scafetta and Schmidt"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

From Watts Up With That?<\/a><\/p>\n\n\n\n

By Andy May<\/p>\n\n\n\n

The argument about the proper way to estimate error in the European Centre for Medium-Range Weather Forecast (ECMWF) ERA5<\/a> weather reanalysis dataset between Nicola Scafetta and Gavin Schmidt has finally been published by Geophysical Research Letters<\/em>. Schmidt, Jones, and Kennedy\u2019s comment is here<\/a> (Schmidt, Jones, & Kennedy, 2023), and Scafetta\u2019s response is here<\/a> (Scafetta N., 2023a).<\/p>\n\n\n\n

I first wrote about this dispute earlier in the year here<\/a>. Nothing much has changed in the final versions.<\/p>\n\n\n\n

Schmidt, Jones, and Kennedy\u2019s assessment of the error in the ERA5 surface temperature dataset average still (incorrectly) assumes that, during such a period, the global surface temperature was constant from 2011-2021 and that its yearly variability is due to random noise. This is clearly a nonphysical interpretation of Earth\u2019s climate, since there are real systematic changes in the climate from year to year, whether one assumes they are due to natural or man-made forces, or both.<\/p>\n\n\n\n

By conflating natural and man-made climatic forces with random noise Schmidt, Jones, and Kennedy inflate the real error of the temperature mean by 5\u201310 times. In fact, a proper analysis of the ensemble of observed global surface temperature members yields a decadal-scale error of about 0.01\u20130.02\u00b0C, as reported in published records<\/a>. BEST (Berkeley Earth Land\/Ocean Temperature record) derives an error of +\/- 0.018- 0.020 \u00b0C for the 11-year period 2011-2021 (1951-1980 anomalies and the April 2023 version of the BEST dataset). Instead, Schmidt, Jones, and Kennedy assessed the error using the standard deviation of the mean (see Chapter 3 here<\/a>) from the period 2011-2021. The equation they use is an equation that can only be used when there are multiple measurements of the same quantity, not eleven annual estimates for eleven different years. It cannot be used to properly estimate the error of a quantity, in this case the average surface temperature of the Earth, that changes naturally and possibly due to human emissions, from year to year.<\/p>\n\n\n\n

Scafetta\u2019s original paper, the reason for the dispute can be downloaded\u00a0here<\/a>. In the paper Scafetta shows that all IPCC\/CMIP6 climate models that result in an ECS[1]<\/a><\/sup>\u00a0that is greater than 3\u00b0C warming per doubling of CO2<\/sub>\u00a0overestimate observed global warming at a statistically significant level. How to determine what is statistically significant is at the heart of the dispute. But statistics or not, Scafetta\u2019s point is apparent in figure 1. When in doubt look at the data.<\/p>\n\n\n\n

\"\"
Figure 1. IPCC\/CMIP6 climate-modeled temperatures (in red) compared to observations (blue, ERA5 2 meter temperatures). Source: (Scafetta N. , 2022a).<\/figcaption><\/figure>\n\n\n\n

In figure 1, the observations are from ECMWF ERA5<\/a>. Clearly, if CO2<\/sub> and other greenhouse gases are causing all the recent warming, as the IPCC AR6 report claims (IPCC, 2021, pp. 425 & 961-962), the climate sensitivity we are observing is lower than 3\u00b0C. Scafetta\u2019s analysis of ECS is very compelling, but there is still more evidence that the higher AR6 ECS estimates are incorrect. For more on this subject, see my four part series on the mysterious AR6 ECS: Part 1<\/a>, Part 2<\/a>, Part 3<\/a>, and Part 4<\/a>. There is also a very good summary of observational estimates of ECS, and a critique of the AR6 methods of determining ECS in Chapter 7 of the Clintel<\/a> volume on AR6, here<\/a>.<\/p>\n\n\n\n

Works Cited<\/h1>\n\n\n\n

Crok, M., & May, A. (2023). The Frozen Climate Views of the IPCC, An Analysis of AR6.<\/em><\/p>\n\n\n\n

IPCC. (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. In V. Masson-Delmotte, P. Zhai, A. Pirani, S. L. Connors, C. P\u00e9an, S. Berger, . . . B. Zhou (Ed.)., WG1.<\/em> Retrieved from https:\/\/www.ipcc.ch\/report\/ar6\/wg1\/<\/a><\/p>\n\n\n\n

Scafetta, N. (2022a). Advanced Testing of Low, Medium, and High ECS CMIP6 GCM Simulations Versus ERA5-T2m. Geophysical Research Letters, 49<\/em>. doi:10.1029\/2022GL097716<\/p>\n\n\n\n

Scafetta, N. (2023a). Reply to \u201cComment on \u2018Advanced testing of low, medium, and high ECS CMIP6 GCM simulations versus ERA5-T2m\u2019. Geophysical Research Letters, 50<\/em>. doi:10.1029\/2023GL104960<\/p>\n\n\n\n

Schmidt, G. A., Jones, G. S., & Kennedy, J. J. (2023). Comment on \u201cAdvanced testing of low, medium, and high ECS CMIP6 GCM simulations versus ERA5-T2m\u201d. Geophysical Research Letters, 50<\/em>. doi:10.1029\/2022GL102530<\/p>\n\n\n\n

Taylor, J. (1997). An Introduction to Error Analysis, second edition.<\/em> University Science Books. Retrieved from https:\/\/www.amazon.com\/Introduction-Error-Analysis-Uncertainties-Measurements\/dp\/093570275X\/ref=monarch_sidesheet<\/a><\/p>\n\n\n\n

    \n
  1. ECS is the equilibrium climate sensitivity, or the ultimate change in global average surface temperature after an instantaneous doubling of CO2<\/sub>. See here<\/a> for more details. \u2191<\/a><\/li>\n<\/ol>\n\n\n\n

    <\/p>\n","protected":false},"excerpt":{"rendered":"

    The argument about the proper way to estimate error in the European Centre for Medium-Range Weather Forecast (ECMWF)\u00a0ERA5\u00a0weather reanalysis dataset between Nicola Scafetta and Gavin Schmidt has finally been published by\u00a0Geophysical Research Letters. Schmidt, Jones, and Kennedy\u2019s comment is\u00a0here\u00a0(Schmidt, Jones, & Kennedy, 2023), and Scafetta\u2019s response is\u00a0here\u00a0(Scafetta N., 2023a).<\/p>\n","protected":false},"author":121246920,"featured_media":210489,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","_crdt_document":"","advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1],"tags":[691819060,691822909,691822908],"class_list":{"0":"post-280164","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","6":"hentry","7":"category-uncategorized","8":"tag-ar6-ecs","9":"tag-era5-surface-temperature","10":"tag-european-centre-for-medium-range-weather-forecast-ecmwf","12":"fallback-thumbnail"},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2022\/07\/00IMAGE-numerical-weather-modeling-050216-1120x534-landscape.jpg?fit=1275%2C717&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-1aSM","jetpack-related-posts":[{"id":252746,"url":"https:\/\/climatescience.press\/?p=252746","url_meta":{"origin":280164,"position":0},"title":"The error of the mean: a dispute between Gavin Schmidt and Nicola Scafetta","author":"uwe.roland.gross","date":"04\/14\/2023","format":false,"excerpt":"\u201cSeveral studies using CMIP6 models suggest that differences in climate sensitivity may be an important factor contributing to the discrepancy between the simulated and observed tropospheric temperature trends (McKitrick and Christy, 2020; 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