{"id":245655,"date":"2023-02-26T13:34:57","date_gmt":"2023-02-26T12:34:57","guid":{"rendered":"https:\/\/climatescience.press\/?p=245655"},"modified":"2023-02-26T13:35:04","modified_gmt":"2023-02-26T12:35:04","slug":"the-holocene-temperature-conundrum","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=245655","title":{"rendered":"The Holocene Temperature Conundrum"},"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

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As my regular readers know, I\u2019ve been writing about the Holocene, especially Holocene climate, for over ten years. My colleagues, Javier Vin\u00f3s and Renee Hannon, have also written extensively on this topic. This fills a void left by the IPCC, which ignores the Holocene, a fact made very clear in my last two posts, here<\/a> and here<\/a>. Here I would like to review a very comprehensive and informative review article<\/a> of what the authors, Darrell S. Kaufman and Ellie Broadman, call \u201cThe Holocene global temperature conundrum.\u201d The paper was published in Nature<\/em> February 15, just a little over a week ago. I was made aware of it by a reader who identifies himself as \u201cMike G,\u201d he was also kind enough to send me a pdf of the article.<\/p>\n\n\n\n

Kaufman and Broadman define the Holocene Temperature Conundrum in this way:<\/p>\n\n\n\n

\n

\u201cA landmark reconstruction of GMST showed peak warmth during the mid-Holocene, when GMST reached about 0.8\u2009\u00b0C higher than that of the preindustrial period. By contrast, early transient climate modelling showed that GMST was around \u22120.5\u2009\u00b0C colder during the mid-Holocene compared with preindustrial [aka Little Ice Age] temperature, followed by continued warming. This discrepancy between the late Holocene global cooling trend inferred from proxy evidence versus the warming trend simulated by climate models is known as the \u2018Holocene temperature conundrum\u2019\u201d(Kaufman & Broadman, 2023)<\/p>\n<\/blockquote>\n\n\n\n

Thus, the proxy evidence we have suggests that the early Holocene global mean surface temperatures (GMST) were warmer than the Little Ice Age (aka the preindustrial period) by about 0.8\u00b0C, but the IPCC\/CMIP6\/PMIP4 climate models suggest that the early Holocene was cooler, by 0.3 to 0.5\u00b0C<\/a> than the Little Ice Age.<\/p>\n\n\n\n

After exhaustively reviewing the evidence for temperature changes in the Holocene, Kaufman and Broadman conclude that global mean surface temperatures (GMST) were<\/em> higher during the Holocene Climatic Optimum, and that subsequent global cooling took place over the following period often called the Neoglacial. Figure 1 is from my previous post, it provides reasonable regional temperature reconstructions for the Arctic, Northern Hemisphere, tropics, Southern Hemisphere, and Antarctica.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 1. The regional temperature reconstructions shown are in 30\u00b0 latitude slices, that is the Arctic (green line) is from 90\u00b0N to 60\u00b0N, the Northern Hemisphere (heavy black line) is from 60\u00b0N to 30\u00b0N, the tropics are from 30\u00b0N to 30\u00b0S, the Southern Hemisphere is from 30\u00b0S to 60\u00b0S and the Antarctic from 60\u00b0S to 90\u00b0S. The Holocene Climatic Optimum warm period, the Mid-Holocene Transition (MHT), and the Neoglacial Period are identified. Sources: (May, 2018, Chapter 4<\/a>) and here<\/a>.<\/p>\n\n\n\n

As Figure 1 makes clear it is difficult to accurately and honestly represent Holocene temperature changes with a \u201cglobal average.\u201d Early in the Holocene the different latitude slices go in different directions and the Neoglacial Period cooling is not truly global, but mostly in the Northern Hemisphere. None-the-less, Kaufman and Broadman conclude:<\/p>\n\n\n\n

\n

\u201cGMST probably peaked sometime late during the first half of the Holocene, at roughly 6.5\u2009ka [4500BC], as evidenced by extensive proxy data and supported by theory and models. Proxy evidence reported in several studies indicates that GMST was roughly 0.5\u2009\u00b0C higher during this millennial-scale period compared with 1850\u20131900, with most of the warming occurring at middle to high latitudes in the Northern Hemisphere.\u201d(Kaufman & Broadman, 2023)<\/p>\n<\/blockquote>\n\n\n\n

Thus, the data runs opposite the models. When I was a computer modeler, this was the end of it, sorry buddy, you blew it. But we live in a different world today. The authors go on to say:<\/p>\n\n\n\n

\n

\u201cOn the modelling side, none of the 16 latest-generation global climate models that participated in the recent CMIP6-PMIP4<\/a>, 6-ka experiment simulated GMST that exceeded their preindustrial control runs. GMST at 6\u2009ka in these models averaged 0.3\u2009\u00b0C cooler than the preindustrial period (Fig. 1b), arguing against a global HTM.\u201d(Kaufman & Broadman, 2023)<\/p>\n<\/blockquote>\n\n\n\n

They provide a plot of the CMIP6 modeled temperature difference between the Holocene Climatic Optimum (HCO) and the Little Ice Age (LIA). It is our Figure 2.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 2. The difference between CMIP6\/PMIP4 climate model temperatures during the Holocene Climatic Optimum and the Little Ice Age. The models hindcast that the Little Ice Age was warmer by 0.3\u00b0C, on average, than the Holocene Climatic Optimum. This is against all proxy evidence and all historical records.<\/p>\n\n\n\n

The map of climate model results in figure 2 is damning enough, but the histogram to the right suggests that the middle Northern Hemisphere latitudes were nearly the same in the HCO and the LIA! We know that cannot be correct. Numerous historical, proxy, and archaeological records from around the world show that the LIA was the coldest and most miserable time<\/a> in human history in the Northern Hemisphere.<\/p>\n\n\n\n

Kaufman and Broadman conclude:<\/p>\n\n\n\n

\n

\u201cIf our preferred interpretation [the HCO was warmer than the LIA] is correct and recent global warming was proceeded by a multimillennial global cooling trend, then this points to the need to improve our understanding of natural climate forcings and feedbacks, along with their representation in climate models. The very large seasonal and latitudinal changes in insolation caused by orbital forcing is the most likely instigator of climate feedbacks over the second half of the Holocene.\u201d(Kaufman & Broadman, 2023)<\/p>\n<\/blockquote>\n\n\n\n

All I have to say is \u201chear! hear!\u201d Climate models are clearly not modeling natural climate change accurately, especially not orbital forcing. If you cannot model natural climate change, you have no idea what the human influence on climate is. If you cannot model the Holocene correctly, you don\u2019t understand climate change.<\/p>\n\n\n\n

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

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

Kaufman, D., & Broadman, E. (2023, February 15). Revisiting the Holocene global temperature conundrum. Nature, 614<\/em>, 425-435. Retrieved from https:\/\/doi.org\/10.1038\/s41586-022-05536-w<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Climate models are clearly not modeling natural climate change accurately, especially not orbital forcing. If you cannot model natural climate change, you have no idea what the human influence on climate is. <\/p>\n","protected":false},"author":121246920,"featured_media":245664,"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":[],"class_list":{"0":"post-245655","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","6":"hentry","7":"category-uncategorized","9":"fallback-thumbnail"},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/02\/image-823.png?fit=1200%2C630&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-11Ub","jetpack-related-posts":[{"id":245453,"url":"https:\/\/climatescience.press\/?p=245453","url_meta":{"origin":245655,"position":0},"title":"Holocene CO2 and the earlier IPCC Reports","author":"uwe.roland.gross","date":"25\/02\/2023","format":false,"excerpt":"\u201c\u2026Holocene \u2026 [is not] considered [a reliable analogue] for a climate with increased concentration of greenhouse gases.\u201d(FAR, page 158-159).","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/02\/image-763.png?fit=1200%2C900&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/02\/image-763.png?fit=1200%2C900&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/02\/image-763.png?fit=1200%2C900&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/02\/image-763.png?fit=1200%2C900&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/02\/image-763.png?fit=1200%2C900&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":222316,"url":"https:\/\/climatescience.press\/?p=222316","url_meta":{"origin":245655,"position":1},"title":"The Last 12,000 Years Show a More Complex Climate History Than Previously Thought","author":"uwe.roland.gross","date":"05\/10\/2022","format":false,"excerpt":"Natural climate variability results from multiple forcings and feedbacks with heterogenous spatiotemporal manifestations.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2022\/10\/image-240.png?fit=1024%2C512&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2022\/10\/image-240.png?fit=1024%2C512&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2022\/10\/image-240.png?fit=1024%2C512&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2022\/10\/image-240.png?fit=1024%2C512&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":387689,"url":"https:\/\/climatescience.press\/?p=387689","url_meta":{"origin":245655,"position":2},"title":"New Study: The Arctic Was 9\u00b0C Warmer Than Today During The Holocene Thermal Maximum","author":"uwe.roland.gross","date":"09\/07\/2025","format":false,"excerpt":"Holocene (11,700 to 8,200 years ago) Arctic (Svalbard) temperatures \u201cwere up to 9\u00b0C higher than today\u201d according to the authors of a\u00a0new\u00a0Nature\u00a0journal study. 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