{"id":452732,"date":"2026-06-28T04:21:55","date_gmt":"2026-06-28T11:21:55","guid":{"rendered":"https:\/\/climatescience.press\/?p=452732"},"modified":"2026-06-28T04:21:57","modified_gmt":"2026-06-28T11:21:57","slug":"2025-study-cloud-effects-reduce-downwelling-longwave-radiation-overriding-the-co2-impact","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=452732","title":{"rendered":"\u00a02025 Study: Cloud Effects Reduce Downwelling Longwave Radiation, Overriding The CO2 Impact"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

From NoTrickTonet<\/a><\/p>\n\n\n\n

By Kenneth Richard<\/a> <\/em><\/p>\n\n\n\n

More observational evidence emerges showing CO2\u2019s effects are too small to drive climate.<\/strong><\/h4>\n\n\n\n

The oft-cited Feldman et al. (2015)<\/a><\/strong> paper proposes to isolate the CO2 impact by only considering a \u201cclear-sky\u201d atmosphere at two sites: the North Slope of Alaska and the Southern Great Plains (USA). In other words, that study can only claim to assess what occurs in an imaginary atmosphere where clouds do not exist \u2013 even though clouds are present about 60-70% of the time in the real-world atmosphere.<\/p>\n\n\n\n

Results indicated that CO2 enhances the downwelling longwave radiative forcing (DLRF) trend, the greenhouse effect, by just 0.2 W\/m\u00b2 per decade (accompanying a 22 ppm CO2 increase from 2000 to 2010).<\/p>\n\n\n\n

\"\"
Image Source: Feldman et al., 2015<\/a><\/strong><\/figcaption><\/figure>\n\n\n\n

But a 2025 paper<\/a><\/strong> quietly published in Nature<\/em> also assessed the contributors to the DLRF trend from 1996-2018 at the Southern Great Plains, even extending their measurements to all land surfaces across the globe from 60\u00b0S to 60\u00b0N.<\/p>\n\n\n\n

But instead of employing only a simulated atmosphere where clouds do not exist, Liu and colleagues provided the all-sky<\/em> values. So, unlike the Feldman paper, they employed the real-world atmosphere which have clouds contributing to (and dominating) the DLRF trend.<\/p>\n\n\n\n

They found observed trends in downwelling longwave show the cloud DLRF contribution actually serves to reduce the greenhouse effect impact by -0.77 to -1.77 W\/m\u00b2 per decade.<\/p>\n\n\n\n

Since the CO2 contribution enhances the trend by only 0.2 W\/m\u00b2 per decade, clouds therefore have been observed to easily outclass and even nullify (net) the effect of CO2 increases.<\/p>\n\n\n\n

The tiny \u201cfinger printed\u201d (FP) decadal effect of CO2 in a real-world, all-sky atmosphere is illustrated (red bar) in the DLRF trend (W\/m\u00b2 per decade) graph. Notice how insignificant the CO2 contribution is compared to the effect of clouds (gray bar).<\/p>\n\n\n\n

Perhaps this is why Feldman and colleagues chose to use an imaginary-world, clear-sky-only atmosphere instead of a real-world, all-sky atmosphere.<\/p>\n\n\n\n

\"\"
Image Source: Liu et al. 2025<\/a><\/strong><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

More observational evidence emerges showing CO2\u2019s effects are too small to drive climate.<\/p>\n","protected":false},"author":121246920,"featured_media":452742,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"jetpack_seo_schema_type":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_wpcom_ai_launchpad_first_post":false,"_jetpack_feature_clip_id":0,"_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":[691829997,691843842,691818296,691843843,691839825,691843844],"class_list":["post-452732","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-carbon-dioxide-co","tag-downwelling-longwave-radiative-forcing-dlrf-trend","tag-greenhouse-effect","tag-north-slope-of-alaska","tag-radiative-forcing","tag-southern-great-plains-usa","fallback-thumbnail"],"jetpack_publicize_connections":[],"jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-1TM8","jetpack-related-posts":[{"id":351059,"url":"https:\/\/climatescience.press\/?p=351059","url_meta":{"origin":452732,"position":0},"title":"\u00a0New Study: Human Contribution To Enhancement Of Earth\u2019s Greenhouse Effect A Negligible 0.2 Percent","author":"uwe.roland.gross","date":"11\/13\/2024","format":false,"excerpt":"\u201c[T]he contribution of CO2 to the greenhouse effect is 4% \u2013 5%. Human CO2 emissions represent 4% of the total, which means that the total human contribution to the enhancement of the greenhouse effect is 0.16% to 0.20% \u2013 a negligible effect.\u201d \u2013 Dr. Demetris Koutsoyiannis (2024)","rel":"","context":"In \"carbon dioxide (CO2)\"","block_context":{"text":"carbon dioxide (CO2)","link":"https:\/\/climatescience.press\/?tag=carbon-dioxide-co2"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/00AdobeStock_266865139.jpg?fit=1200%2C668&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/00AdobeStock_266865139.jpg?fit=1200%2C668&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/00AdobeStock_266865139.jpg?fit=1200%2C668&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/00AdobeStock_266865139.jpg?fit=1200%2C668&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/00AdobeStock_266865139.jpg?fit=1200%2C668&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":350651,"url":"https:\/\/climatescience.press\/?p=350651","url_meta":{"origin":452732,"position":1},"title":"Relative importance of carbon dioxide and water in the greenhouse effect: Does the tail wag the dog?","author":"uwe.roland.gross","date":"11\/08\/2024","format":false,"excerpt":"In his paper,\u00a0\u201cRelative Importance of Carbon Dioxide and Water in the Greenhouse Effect: Does the Tail Wag the Dog?\u201d, Demetris Koutsoyiannis explores the greenhouse effect\u2019s primary drivers, positing that water vapor and clouds vastly overshadow carbon dioxide (CO\u2082) in terms of their contribution.","rel":"","context":"In \"carbon dioxide (CO2)\"","block_context":{"text":"carbon dioxide (CO2)","link":"https:\/\/climatescience.press\/?tag=carbon-dioxide-co2"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/0-clouds-on-the-sky.jpeg?fit=1200%2C797&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/0-clouds-on-the-sky.jpeg?fit=1200%2C797&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/0-clouds-on-the-sky.jpeg?fit=1200%2C797&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/0-clouds-on-the-sky.jpeg?fit=1200%2C797&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/11\/0-clouds-on-the-sky.jpeg?fit=1200%2C797&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":344580,"url":"https:\/\/climatescience.press\/?p=344580","url_meta":{"origin":452732,"position":2},"title":"Scientists: Climate Forcing Measurement Errors Are \u2018Only\u2019 150 Times Larger Than For CO2 Climate Forcing","author":"uwe.roland.gross","date":"09\/25\/2024","format":false,"excerpt":"When assessing the climate-altering effects of downwelling longwave radiation, the root mean square error associated with calculating this value is 29.7 W\/m\u00b2. 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