{"id":267979,"date":"2023-07-17T20:44:21","date_gmt":"2023-07-17T18:44:21","guid":{"rendered":"https:\/\/climatescience.press\/?p=267979"},"modified":"2023-07-17T20:44:31","modified_gmt":"2023-07-17T18:44:31","slug":"the-urban-heat-island-effect-in-ghcn-station-temperatures-urban-locations-show-large-spurious-warming-effects","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=267979","title":{"rendered":"The Urban Heat Island Effect in GHCN Station Temperatures: Urban Locations show Large Spurious Warming Effects"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

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

From Roy Spencer, PhD.<\/a><\/p>\n\n\n\n

July 17th, 2023 by Roy W. Spencer, Ph. D.<\/small><\/p>\n\n\n\n

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

It has been a while since I have posted progress on our DOE-funded research into the Urban Heat Island (UHI) effect in the GHCN station temperatures used to monitor land-based global warming. It should be remembered that everything I post on this subject is (as is usually the case) a work in progress.<\/p>\n\n\n\n

What I am addressing is the existence of localized long-term warming associated with population increases which are over-and-above the large-scale warming due to humans or nature. These urban-influenced changes are very localized, and yet they influence large-scale area averages and make the land areas look like they are warming faster than they really are. The problem is pervasive because virtually all thermometer locations are where people live, and since the 1800s even most rural locations have experienced population growth.<\/p>\n\n\n\n

The bottom line is that there are UHI-based trend (warming) effects in the GHCN station temperatures; the only question is, how much have they affected reported temperature trends? Most previously published research on the subject has suggested the effects are small (Hausfather et al., 2013; Wickham et al., 2013; Hansen et al., 2010; Parker, 2010; Jones et al., 2008; Parker, 2006; Peterson & Owen, 2005; Peterson, 2003; Peterson et al., 1999; Gallo et al., 1999; Karl et al., 1988). As a result, you will find most who defend the \u201cclimate crisis\u201d narrative will refer to one or more of those studies as showing the \u201cscience is settled\u201d, and that GHCN-based land warming estimates are largely free of UHI warming effects.<\/p>\n\n\n\n

I have argued that those studies involved methodologies that were not very good. Identifying the UHI effect is difficult. I\u2019ve come up with a novel way of quantifying the average UHI effect, even at stations that would be considered \u201crural\u201d with presumably no UHI effect. We have a paper in review in\u00a0Nature Scientific Reports<\/em>\u00a0describing the methodology (my blog description of the methodology is\u00a0here<\/a>), but I have no idea what chance it has of being published.<\/p>\n\n\n\n

I will get right to the results as they stand today. What I show below are for the all-station average of GHCN stations; they are NOT area averages, which are what is needed for climate monitoring. They just show how much the average GHCN station is influenced by spurious UHI warming. The stations cover the latitude bands from 20N to 80N, but are dominated by U.S. stations (about 80% of the total) due to the huge numbers of stations we have in this country.<\/p>\n\n\n\n

The plots are for 4 classes of initial GHCN station population density (the first year those stations started operating) during the warm season (May\/June\/July), and give the cumulative year-on-year temperature increase averaged across all stations in each of the four initial station population classes. The adjusted (homogenized) GHCN station temperature changes are in green, and my calculated UHI effect is in red.<\/p>\n\n\n\n

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

For the \u201cwilderness to very rural\u201d class (upper-left panel), the UHI effect on temperature trends turns out to be quite small, contrary to what I have\u00a0recently argued<\/a>. Since many of these low-population stations are at high northern latitudes, this would suggest that the UHI effects on the large warming trends reported there are small.<\/p>\n\n\n\n

But as we progress to higher population stations, we find that UHI warming effect becomes larger. In the highest population density class (\u201csuburban to urban\u201d, lower-right panel) my calculation of UHI warming is virtually the entire GHCN-reported warming signal since 1880, but only a small part of the reported warming since 1980.<\/p>\n\n\n\n

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

If these results stand, what will they mean for reported land warming trends?<\/strong><\/p>\n\n\n\n

I\u2019m guessing that the UHI effect on area-average trends since 1980 (the period of most rapid temperature rise) will turn out to be relatively small. But before 1980 it looks like the UHI effect on GHCN temperatures could be substantial. This would change the nature of the global warming narrative, with little land-based warming for the first 100 years starting in 1880.<\/p>\n\n\n\n

What could change these results? First, I do not account for increases in the UHI effect due to per-capita increases in infrastructure and energy use (buildings, vehicles, parking lots, electricity use and resulting waste heat). I assume the UHI effect is only a function of population density (partly because we have global gridpoint data on population extending back into the 1800s). Thus, my UHI warming estimates might be a little low for stations where population stopped growing but spurious sources of heat continued to increase, such as in Vienna, Austria (R. Bohm,\u00a0Climatic Change<\/em>, 1998).<\/p>\n\n\n\n

In any event, I feel like I am finally converging on useful results. One aspect of this is that the record high temperatures now being reported in major population centers in the southwest U.S. and southern Europe need to be revisited based upon the very large urban heat island temperature increases seen in the lower-right panel of the above plot at suburban-to-urban stations.<\/p>\n\n\n\n

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

It has been a while since I have posted progress on our DOE-funded research into the Urban Heat Island (UHI) effect in the GHCN station temperatures used to monitor land-based global warming. It should be remembered that everything I post on this subject is (as is usually the case) a work in progress.<\/p>\n","protected":false},"author":121246920,"featured_media":267987,"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":[691821157,691821158,691821156,691821159],"class_list":{"0":"post-267979","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","6":"hentry","7":"category-uncategorized","8":"tag-ghcn-station-temperatures","9":"tag-uhi-warming-effects","10":"tag-urban-heat-island-uhi","11":"tag-warming-trends","13":"fallback-thumbnail"},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/07\/03_urbanheatisland.webp?fit=1024%2C552&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-17If","jetpack-related-posts":[{"id":349393,"url":"https:\/\/climatescience.press\/?p=349393","url_meta":{"origin":267979,"position":0},"title":"A Demonstration: Low Correlations Do Not Necessarily Lead to Low Confidence in Data Regressions","author":"uwe.roland.gross","date":"29\/10\/2024","format":false,"excerpt":"In a recent post I used our new Urban Heat Island (UHI) warming estimates at individual U.S. GHCN stations having at least 120 years of data to demonstrate that the homogenized (adjusted) GHCN data still contain substantial UHI effects. Therefore, spurious warming from UHI effects is inflating reported U.S. warming\u2026","rel":"","context":"In \"GHCN data\"","block_context":{"text":"GHCN data","link":"https:\/\/climatescience.press\/?tag=ghcn-data"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0urbanheatisland.jpg?fit=1200%2C648&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0urbanheatisland.jpg?fit=1200%2C648&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0urbanheatisland.jpg?fit=1200%2C648&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0urbanheatisland.jpg?fit=1200%2C648&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0urbanheatisland.jpg?fit=1200%2C648&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":348954,"url":"https:\/\/climatescience.press\/?p=348954","url_meta":{"origin":267979,"position":1},"title":"Urban Heat Island Effects Have Not Yet Been Removed from Official GHCN Warming Trends","author":"uwe.roland.gross","date":"26\/10\/2024","format":false,"excerpt":"Our paper (co-authored by John Christy and Danny Braswell) on computing the urban heat island (UHI) effect as a function of population density (PD) is now in the final stages of review after a 3rd round of edits, and I\u2019m hopeful it will be accepted for publication soon.","rel":"","context":"In \"GHCN Warming Trends\"","block_context":{"text":"GHCN Warming Trends","link":"https:\/\/climatescience.press\/?tag=ghcn-warming-trends"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0Screenshot-2024-10-26-083344.png?fit=1200%2C851&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0Screenshot-2024-10-26-083344.png?fit=1200%2C851&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0Screenshot-2024-10-26-083344.png?fit=1200%2C851&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0Screenshot-2024-10-26-083344.png?fit=1200%2C851&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0Screenshot-2024-10-26-083344.png?fit=1200%2C851&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":378577,"url":"https:\/\/climatescience.press\/?p=378577","url_meta":{"origin":267979,"position":2},"title":"Our Urban Heat Island Paper Has Been Published","author":"uwe.roland.gross","date":"16\/05\/2025","format":false,"excerpt":"It took the better part of two years to satisfy the reviewers, but finally our paper\u00a0Urban Heat Island Effects in U.S. Summer Surface Temperature Data, 1895\u20132023\u00a0has been published in the AMS\u00a0Journal of Applied Meteorology and Climatology.","rel":"","context":"In \"GHCN stations\"","block_context":{"text":"GHCN stations","link":"https:\/\/climatescience.press\/?tag=ghcn-stations"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/00glo-urban-heat-island-effect.webp?fit=1200%2C690&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/00glo-urban-heat-island-effect.webp?fit=1200%2C690&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/00glo-urban-heat-island-effect.webp?fit=1200%2C690&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/00glo-urban-heat-island-effect.webp?fit=1200%2C690&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/00glo-urban-heat-island-effect.webp?fit=1200%2C690&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":280654,"url":"https:\/\/climatescience.press\/?p=280654","url_meta":{"origin":267979,"position":3},"title":"Summer warming 1895-2023 in U.S. cities exaggerated by 100% from the urban heat island effect","author":"uwe.roland.gross","date":"27\/09\/2023","format":false,"excerpt":"We are now getting close to finalizing our methodology for computing the urban heat island (UHI) effect as a function of population density, and will be submitting our first paper for publication in the next few weeks. I\u2019ve settled on using the CONUS (Lower 48) U.S. region as a demonstration\u2026","rel":"","context":"In \"1895-2023\"","block_context":{"text":"1895-2023","link":"https:\/\/climatescience.press\/?tag=1895-2023"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/01895-2023-CONUS-JJA-time-series-for-blog-post.jpg?fit=1200%2C675&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/01895-2023-CONUS-JJA-time-series-for-blog-post.jpg?fit=1200%2C675&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/01895-2023-CONUS-JJA-time-series-for-blog-post.jpg?fit=1200%2C675&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/01895-2023-CONUS-JJA-time-series-for-blog-post.jpg?fit=1200%2C675&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/01895-2023-CONUS-JJA-time-series-for-blog-post.jpg?fit=1200%2C675&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":287175,"url":"https:\/\/climatescience.press\/?p=287175","url_meta":{"origin":267979,"position":4},"title":"Examples from our New UAH Urban Heat Island Dataset","author":"uwe.roland.gross","date":"08\/11\/2023","format":false,"excerpt":"Over 50% of the population now lives in urban areas, and that fraction is supposed to approach 70% by 2045. From Roy Spencer, PhD. November 7th, 2023 by Roy W. Spencer, Ph. D. Since few people who visit here will actually download and analyze data, I present some imagery of\u2026","rel":"","context":"In \"1880 through 2023\"","block_context":{"text":"1880 through 2023","link":"https:\/\/climatescience.press\/?tag=1880-through-2023"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00heatwaves.jpg?fit=1128%2C564&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00heatwaves.jpg?fit=1128%2C564&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00heatwaves.jpg?fit=1128%2C564&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00heatwaves.jpg?fit=1128%2C564&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00heatwaves.jpg?fit=1128%2C564&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":255147,"url":"https:\/\/climatescience.press\/?p=255147","url_meta":{"origin":267979,"position":5},"title":"Urbanization Effects on GHCN Temperature Trends, Part IV: UHI Effects on Tmax and Tmin","author":"uwe.roland.gross","date":"28\/04\/2023","format":false,"excerpt":"This is part 4 of my series on quantifying Urban Heat Island (UHI) effects on surface air temperatures as reported in the monthly GHCN datasets produced by NOAA.","rel":"","context":"In \"GHCN temperature trends\"","block_context":{"text":"GHCN temperature trends","link":"https:\/\/climatescience.press\/?tag=ghcn-temperature-trends"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/00UHI-May-June-July-Tmax-Tmin-2.jpg?fit=864%2C960&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/00UHI-May-June-July-Tmax-Tmin-2.jpg?fit=864%2C960&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/00UHI-May-June-July-Tmax-Tmin-2.jpg?fit=864%2C960&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/00UHI-May-June-July-Tmax-Tmin-2.jpg?fit=864%2C960&ssl=1&resize=700%2C400 2x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/267979","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/users\/121246920"}],"replies":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=267979"}],"version-history":[{"count":7,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/267979\/revisions"}],"predecessor-version":[{"id":267989,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/267979\/revisions\/267989"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/media\/267987"}],"wp:attachment":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=267979"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=267979"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=267979"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}