{"id":253872,"date":"2023-04-21T11:01:14","date_gmt":"2023-04-21T09:01:14","guid":{"rendered":"https:\/\/climatescience.press\/?p=253872"},"modified":"2023-04-21T11:01:18","modified_gmt":"2023-04-21T09:01:18","slug":"earths-mean-annual-temperature-was-warmer-31000-years-agothe-north-pole-22c-warmer","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=253872","title":{"rendered":"Earth\u2019s Mean Annual Temperature Was Warmer 31,000 Years Ago\u2026The North Pole 22\u00b0C Warmer"},"content":{"rendered":"\n
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From NoTricksZone<\/a><\/p>\n\n\n\n

By\u00a0Kenneth Richard<\/a>\u00a0on\u00a0<\/em>17. April 2023<\/p>\n\n\n\n

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Earth\u2019s average annual temperature fluctuated by as much as 35\u00b0C (at high latitudes) from one millennial-scale period to the next during the last glacial period.<\/strong><\/h4>\n\n\n\n
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A recently-published 2-part study (Smul\u2032skii, 2022a<\/a><\/strong> and 2022b<\/a><\/strong>) utilizes established orbital and insolation data to calculate Earth\u2019s average temperature today (0 k years ago), 14.4\u00b0C, and at 25\u00b0N, 45\u00b0N, 65\u00b0N, 80\u00b0N, 0\u00b0, -25\u00b0S, -45\u00b0S, -65\u00b0S, and -80\u00b0S during 3 paleo epochs: 15.9 k years ago, 31.3 k years ago, and 46.4 k years ago.<\/p>\n\n\n\n

Global annual temperature of Earth: 14.4\u00b0C \u2013 the same as a century ago<\/strong><\/p>\n\n\n\n

Consistent with dozens of other calculations, Smul\u2032skii (2022a<\/a><\/strong>) determined the mean annual temperature of the modern period, which includes 1991-2018, ranges between 14.07 and 14.41\u00b0<\/strong>C.<\/p>\n\n\n

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This calculation is similar to what Jones et al. determined as Earth\u2019s temperature in a\u00a01999 study<\/a><\/strong>: 14.0\u00b0<\/strong>C.<\/p>\n\n\n\n

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Image Source:\u00a0Jones et al., 1999<\/a><\/strong><\/h6>\n\n\n\n

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Kramm et al., (2020<\/a><\/strong>) reported the generally agreed-upon global temperature from 1877 to 1913 from dozens of calculated results was also about 14.4\u00b0C.<\/p>\n\n\n\n

HadCRUT, Berkley, and NASA GISS indicate the 1991-2018 period\u2019s global annual surface temperature has also been 14.5\u00b0C. Thus, as these geoscientists conclude, there  has been \u201cno change in the globally averaged near-surface temperature over the past 100 years<\/strong>\u201d.<\/p>\n\n\n

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Image Source:\u00a0Kramm et al., 2020<\/a><\/strong><\/h6>\n\n\n\n

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The global annual temperature was warmer than today during the last glacial period<\/strong><\/p>\n\n\n\n

Even though atmospheric CO2 concentrations were said to be about 200 ppm 31.3 k years ago, or during the last glacial, Earth was significantly warmer than it is today \u2013 especially at the higher latitudes.<\/p>\n\n\n\n

At 65\u00b0N, for example, the mean annual temperatures were 0.66\u00b0C 31.3 k years ago, but -5.6\u00b0C today. In other words, it was 6.3\u00b0C warmer during the last glacial at this latitude.<\/p>\n\n\n\n

At 90\u00b0N, mean annual temperatures were -2.65\u00b0C 31.3 k years ago, but -25.3\u00b0C today. The modern North Pole is thus ~22\u00b0C colder than it was during the \u201cKarginsky Interglacial\u201d (31.3 k years ago). At 90\u00b0S, mean annual temperatures were ~27\u00b0C warmer than today (-31.1\u00b0C vs. -4.1\u00b0C) 31.3 k years ago.<\/p>\n\n\n

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Image Source:\u00a0Smul\u2019skii, 2022b<\/a><\/strong><\/h6>\n\n\n\n

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Averaged over the entire Earth, the mean annual temperature was 0.4\u00b0C warmer than modern (14.8\u00b0C) 31.3 k years ago, and -0.4\u00b0C colder than modern (14.0\u00b0C) 46.4 k years ago, or during the coldest period in the last 200,000 years.<\/p>\n\n\n\n

Mean annual temperature swings ranging from -3.4\u00b0C at 80\u00b0N 111.8 k years ago to -40.9\u00b0C at 80\u00b0N 46.4 k years ago suggest millennial-scale climate variations as high as 35\u00b0C occur naturally in the Earth\u2019s climate system.<\/p>\n\n\n\n

Other paleoclimate studies also document a warm period 31.3 k years ago<\/strong><\/p>\n\n\n\n

These global to regional temperature variations are consistent with independent paleoclimate research. For example, about 31.3 k years ago (\u201c31,436 \u2013 31,178 cal BP\u201d) temperatures in the Russian Altai mountains (49\u00b0N) were thought to be 5.9\u00b0C warmer than today (Ganyushkin et al., 2018<\/a><\/strong>) given the presence of tree remains at much higher altitudes (500 m) than the modern tree line dating to that period.<\/p>\n\n\n

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Image Source:\u00a0Ganyushkin et al., 2018<\/a><\/strong><\/h6>\n\n\n\n

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Scientists document a Siberian Arctic with \u201cwarmer-than-today temperatures (by up to 4 \u2013 4.5\u00b0C)\u2026between about 39 and 31 cal kyr BP\u201d (Wetterich et al., 2021<\/a><\/strong>).<\/p>\n\n\n

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Image Source:\u00a0Wetterich et al., 2021<\/a><\/strong><\/h6>\n\n\n\n

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There were ~5\u00b0C warmer glacial climates (July) than today throughout Northern Asia during the millennia between 50 k and 20 k years ago (Tarasov et al., 2021<\/a><\/strong>).<\/p>\n\n\n\n

\u201c\u2026reconstructed mean July temperatures above 12\u00b0C for most of the last cold stage [glacial] in the study area [throughout Northern Asia], where modern mean July temperatures are about 7\u00b0C\u201d.<\/em><\/h6>\n\n\n\n

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The widespread presence of grazing mammoths, horses, bison, deer, antelope, gazelle\u2026in Siberia and Alaska and well north of the Arctic circle imply \u201cyear-round grazing grounds.\u201d This requires warmer temperatures and more pervasive ice-free grass-grazing ranges than exist today.<\/p>\n\n\n

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Image Source:\u00a0Tarasov et al., 2021<\/a><\/strong><\/h6>\n\n\n\n

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In the North Pacific ~35 k to 18 k years ago temperatures ranged between 10 and 16\u00b0C versus 9.1\u00b0C today (Max et al., 2020<\/a><\/strong>).<\/p>\n\n\n

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Image Source:\u00a0Max et al., 2020<\/a><\/strong><\/h6>\n\n\n\n

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In southern California temperatures reached 22-23\u00b0C 31 k to 24 k years ago, whereas they are only 18\u00b0C today (Feakins et al., 2019<\/a><\/strong>).<\/p>\n\n\n

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Image Source: Feakins et al., 2019<\/a><\/strong><\/h6>\n\n\n\n

In the Southern Hemisphere, the Southern Ocean\u2019s surface temperatures peaked at 13.6\u00b0C about 22 k years ago. From 35 to 30 k years ago temperatures ranged from 12-13\u00b0C versus 8.5\u00b0C today (3.5 to 4.5\u00b0C warmer). There were \u201chigher SST during the 40-24 kyrs period than during the Holocene\u201d (Civel-Mazens et al., 2021<\/a><\/strong>).<\/p>\n\n\n

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Image Source:\u00a0Civel-Mazens et al., 2021<\/a><\/strong><\/h6>\n\n\n\n

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It was 2-5\u00b0C warmer than today in the South Atlantic from about 65 k to 30 k years ago, \u201cprompting us to exclude atmospheric pCO2 as a direct driver of SST variations in the southern WTA [Western Tropical Atlantic]\u201d  (Hou et al., 2020<\/a><\/strong>).<\/p>\n\n\n

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Image Source:\u00a0Hou et al., 2020<\/a><\/strong><\/h6>\n\n\n\n

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In sum, none of these studies support the conclusion that CO2 concentrations are a driver of surface temperatures. Earth\u2019s mean annual temperatures have been much warmer (or colder) than today, regardless of the CO2 concentration.<\/p>\n\n\n\t

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