{"id":378577,"date":"2025-05-16T08:54:21","date_gmt":"2025-05-16T06:54:21","guid":{"rendered":"https:\/\/climatescience.press\/?p=378577"},"modified":"2025-05-16T08:54:23","modified_gmt":"2025-05-16T06:54:23","slug":"our-urban-heat-island-paper-has-been-published","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=378577","title":{"rendered":"Our Urban Heat Island Paper Has Been Published"},"content":{"rendered":"\n
\"\"
Heatwave over a city, bright sun, global warming, urban heat island. Generative AI<\/figcaption><\/figure>\n\n\n\n

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

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

May 15th, 2025 by Roy W. Spencer, Ph. D.<\/p>\n\n\n

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

It took the better part of two years to satisfy the reviewers, but finally our paper Urban Heat Island Effects in U.S. Summer Surface Temperature Data, 1895\u20132023<\/a> has been published in the AMS Journal of Applied Meteorology and Climatology<\/em>.<\/p>\n\n\n\n

To quickly summarize, we used the average temperature differences between nearby GHCN stations and related those to population density (PD) differences between stations. Why population density? Well, PD datasets are global, and one of the PD datasets goes back to the early 1800s, so we can compute how the UHI effect has changed over time. The effect of PD on UHI temperature is strongly nonlinear, so we had to account for that, too. (The strongest rate of warming occurs when population just starts to increase beyond wilderness conditions, and it mostly stabilizes at very high population densities; This has been known since Oke\u2019s original 1973 study<\/a>).<\/p>\n\n\n\n

We then created a dataset of UHI warming versus time at the gridpoint level by calibrating population density increases in terms of temperature increase.<\/p>\n\n\n\n

The bottom line was that 65% of the U.S. linear warming trend between 1895 and 2023 was due to increasing population density at the suburban and urban stations; 8% of the warming was due to urbanization at rural stations. Most of that UHI effect warming occurred before 1970.<\/p>\n\n\n\n

But this does not necessarily translate into NOAA\u2019s official temperature record being corrupted at these levels. Read on\u2026<\/p>\n\n\n\n

What Does This Mean for Urbanization Effects in the Official U.S. Temperature Record?<\/strong><\/p>\n\n\n\n

That\u2019s a good question, and I don\u2019t have a good answer.<\/p>\n\n\n\n

One of the reviewers, who seemed to know a lot about the homogenization technique used by NOAA, said the homogenized data could not be used for our study because the UHI-trends are mostly removed from those data. (Homogenization looks at year-to-year [time domain] temperature changes at neighboring stations, not the spatial temperature differences [space domain] like we do). So, we were forced to use the raw (not homogenized) U.S. summertime GHCN daily average ([Tmax+Tmin]\/2) data for the study. One of the surprising things that reviewer claimed was that homogenization warms the past at currently urbanized stations to make their less-urbanized early history just as warm as today.<\/p>\n\n\n\n

So, I emphasize: In our study, it was the raw<\/em> (unadjusted) data which had a substantial UHI warming influence. This isn\u2019t surprising.<\/p>\n\n\n\n

But that reviewer of the paper said most of the spurious UHI warming effect has been removed by the homogenization process, which constitutes the official temperature record as reported by NOAA. I am not convinced of this, and at least one recent paper<\/a> claims that homogenization does not actually correct the urban trends to look like rural trends, but instead it does \u201curban blending\u201d of the data. As a result, which trends are \u201cpreferred\u201d by that statistical procedure are based upon a sort of \u201cstatistical voting\u201d process (my terminology here, which might not be accurate).<\/p>\n\n\n\n

So, it remains to be seen just how much spurious UHI effect there is in the official, homogenized land-based temperature trends. The jury is still out on that.<\/p>\n\n\n\n

Of course, if sufficient rural<\/em> stations can be found to do land-based temperature monitoring, I still like Anthony Watts\u2019 approach of simply not using suburban and urban sites for long-term trends. Nevertheless, most people live in urbanized areas<\/em>, so it\u2019s still important to quantify just how much of those \u201crecord hot\u201d temperatures we hear about in cities are simply due to urbanization effects. I think our approach gets us a step closer to answering that question.<\/p>\n\n\n\n

Is Population Density the Best Way to Do This?<\/strong><\/p>\n\n\n\n

We used PD data because there are now global datasets, and at least one of them extends centuries into the past. But, since we use population density in our study, we cannot account for additional UHI effects due to increased prosperity even when population has stabilized.<\/p>\n\n\n\n

For example, even if population density no longer increases over time in some urban areas, there have likely been increases in air conditioning use, with more stores and more parking lots, as wealth has increased since, say, the 1970s. We have started using a Landsat-based dataset of \u201cimpervious surfaces\u201d to try to get at part of this issue, but those data only go back to the mid-1970s. But it will be a start.<\/p>\n\n\n\n

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

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.<\/p>\n","protected":false},"author":121246920,"featured_media":280014,"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":[691824428,691835123,691833237,691831104],"class_list":{"0":"post-378577","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","6":"hentry","7":"category-uncategorized","8":"tag-ghcn-stations","9":"tag-increasing-population-density","10":"tag-noaa-national-oceanic-and-atmospheric-administration","11":"tag-urban-heat-island-effects","13":"fallback-thumbnail"},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/09\/00glo-urban-heat-island-effect.webp?fit=1280%2C736&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-1Au5","jetpack-related-posts":[{"id":287490,"url":"https:\/\/climatescience.press\/?p=287490","url_meta":{"origin":378577,"position":0},"title":"The Urban Heat Island Effect – Dramatic New Findings With Dr. Roy Spencer","author":"uwe.roland.gross","date":"10\/11\/2023","format":false,"excerpt":"This week on \"Climate Change Roundtable,\" host Anthony Watts and panelists Linnea Lueken and H. Sterling Burnett will discuss the the big white elephant in the climate room: urban heat islands (UHI), a significant but often overlooked topic in climate science. This phenomenon has been known for decades, yet climate\u2026","rel":"","context":"In \"Dr. Roy Spencer\"","block_context":{"text":"Dr. Roy Spencer","link":"https:\/\/climatescience.press\/?tag=dr-roy-spencer"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00Screenshot-2023-11-10-195427.png?fit=982%2C563&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00Screenshot-2023-11-10-195427.png?fit=982%2C563&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00Screenshot-2023-11-10-195427.png?fit=982%2C563&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/00Screenshot-2023-11-10-195427.png?fit=982%2C563&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":284165,"url":"https:\/\/climatescience.press\/?p=284165","url_meta":{"origin":378577,"position":1},"title":"New paper submission: Urban heat island effects in U.S. summer temperatures, 1880-2015","author":"uwe.roland.gross","date":"20\/10\/2023","format":false,"excerpt":"Urban heat islands concern both the temperature of various surfaces (streets, roofs, etc.) and the atmosphere.\u00a0The absorbed\u00a0heat during the day by the urban infrastructure is given away slowly \u2013 therefore also at night. From \u00a0Roy Spencer, PhD. October 19th, 2023 by Roy W. Spencer, Ph. D. After years of dabbling\u2026","rel":"","context":"In \"John Christy\"","block_context":{"text":"John Christy","link":"https:\/\/climatescience.press\/?tag=john-christy"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/10\/0shutterstock_666649831-1024x629-1.png?fit=1024%2C629&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/10\/0shutterstock_666649831-1024x629-1.png?fit=1024%2C629&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/10\/0shutterstock_666649831-1024x629-1.png?fit=1024%2C629&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/10\/0shutterstock_666649831-1024x629-1.png?fit=1024%2C629&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":378625,"url":"https:\/\/climatescience.press\/?p=378625","url_meta":{"origin":378577,"position":2},"title":"SHOCK CLIMATE REPORT! Urban Heat Islands Responsible for 65% of Global Warming","author":"uwe.roland.gross","date":"16\/05\/2025","format":false,"excerpt":"A new study from the University of Alabama in Huntsville addresses the question of how much the Urban Heat Island (UHI) effect is responsible for the higher temperatures at weather stations across the world. Dr. Roy Spencer and Dr. John Christy have spent several years developing a novel method that\u2026","rel":"","context":"In \"climactic \u201cgolden age\u201d\"","block_context":{"text":"climactic \u201cgolden age\u201d","link":"https:\/\/climatescience.press\/?tag=climactic-golden-age"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/05\/0Screenshot-2025-05-16-165630.png?fit=1200%2C671&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/05\/0Screenshot-2025-05-16-165630.png?fit=1200%2C671&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/05\/0Screenshot-2025-05-16-165630.png?fit=1200%2C671&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/05\/0Screenshot-2025-05-16-165630.png?fit=1200%2C671&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/05\/0Screenshot-2025-05-16-165630.png?fit=1200%2C671&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":252651,"url":"https:\/\/climatescience.press\/?p=252651","url_meta":{"origin":378577,"position":3},"title":"Classifying Land Temperature Stations as Either \u201cUrban\u201d or \u201cRural\u201d in UHI Studies Proves Nothing about Spurious Temperature Trends","author":"uwe.roland.gross","date":"13\/04\/2023","format":false,"excerpt":"The mistake people have made is to assume that just because urban locations are warmer than rural locations\u00a0at any given time\u00a0that they then have a much larger spurious warming impact on\u00a0trends over time.\u00a0That is simply not true.","rel":"","context":"In \"Land Temperature Stations\"","block_context":{"text":"Land Temperature Stations","link":"https:\/\/climatescience.press\/?tag=land-temperature-stations"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/0-ghost-45.jpeg?fit=1200%2C989&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/0-ghost-45.jpeg?fit=1200%2C989&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/0-ghost-45.jpeg?fit=1200%2C989&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/0-ghost-45.jpeg?fit=1200%2C989&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/04\/0-ghost-45.jpeg?fit=1200%2C989&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":280654,"url":"https:\/\/climatescience.press\/?p=280654","url_meta":{"origin":378577,"position":4},"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":407122,"url":"https:\/\/climatescience.press\/?p=407122","url_meta":{"origin":378577,"position":5},"title":"The Guardian Is Wrong: Cities Are Hotter Because of the UHI Effect, Not Increased CO\u2082","author":"uwe.roland.gross","date":"08\/10\/2025","format":false,"excerpt":"The Guardian published an article, \u201cWorld\u2019s major cities hit by 25% leap in extremely hot days since the 1990s,\u201d asserting that global warming has caused a sharp rise in the number of extremely hot days in cities worldwide, citing an International Institute for Environment and Development analysis that claims urban\u2026","rel":"","context":"In \"1540 megadrought\"","block_context":{"text":"1540 megadrought","link":"https:\/\/climatescience.press\/?tag=1540-megadrought"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/10\/0AQPKDRdw0NUnHkE5lEr4_zU5Od109A6VZuKSZb7d9ssAuE9rQRwSdrBWJqxKvZ7YHap1bJ-lm4Yy8L9oX72OAw9rW1g20gvm-mxuJWuDwv6VlgisSfWisgrHjDi3yZmB-1.jpeg?fit=1200%2C648&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/10\/0AQPKDRdw0NUnHkE5lEr4_zU5Od109A6VZuKSZb7d9ssAuE9rQRwSdrBWJqxKvZ7YHap1bJ-lm4Yy8L9oX72OAw9rW1g20gvm-mxuJWuDwv6VlgisSfWisgrHjDi3yZmB-1.jpeg?fit=1200%2C648&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/10\/0AQPKDRdw0NUnHkE5lEr4_zU5Od109A6VZuKSZb7d9ssAuE9rQRwSdrBWJqxKvZ7YHap1bJ-lm4Yy8L9oX72OAw9rW1g20gvm-mxuJWuDwv6VlgisSfWisgrHjDi3yZmB-1.jpeg?fit=1200%2C648&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/10\/0AQPKDRdw0NUnHkE5lEr4_zU5Od109A6VZuKSZb7d9ssAuE9rQRwSdrBWJqxKvZ7YHap1bJ-lm4Yy8L9oX72OAw9rW1g20gvm-mxuJWuDwv6VlgisSfWisgrHjDi3yZmB-1.jpeg?fit=1200%2C648&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/10\/0AQPKDRdw0NUnHkE5lEr4_zU5Od109A6VZuKSZb7d9ssAuE9rQRwSdrBWJqxKvZ7YHap1bJ-lm4Yy8L9oX72OAw9rW1g20gvm-mxuJWuDwv6VlgisSfWisgrHjDi3yZmB-1.jpeg?fit=1200%2C648&ssl=1&resize=1050%2C600 3x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/378577","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=378577"}],"version-history":[{"count":4,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/378577\/revisions"}],"predecessor-version":[{"id":378582,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/378577\/revisions\/378582"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/media\/280014"}],"wp:attachment":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=378577"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=378577"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=378577"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}