{"id":367691,"date":"2025-02-26T08:41:23","date_gmt":"2025-02-26T07:41:23","guid":{"rendered":"https:\/\/climatescience.press\/?p=367691"},"modified":"2025-02-26T08:44:25","modified_gmt":"2025-02-26T07:44:25","slug":"new-study-reveals-unexpected-decline-in-ocean-evaporation-amid-rising-sea-temperatures","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=367691","title":{"rendered":"New Study Reveals Unexpected Decline in Ocean Evaporation Amid Rising Sea Temperatures"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

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

From Watts Up With That?<\/a><\/p>\n\n\n\n

From Charles Rotter<\/a><\/p>\n\n\n\n

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

A recent study published in Geophysical Research Letters<\/a><\/em>, has turned up a surprising result: global ocean evaporation, a cornerstone of the hydrological cycle, has been declining since the late 2000s despite steadily warming sea surfaces. This runs counter to the widely held view that a warmer climate should boost evaporation rates. For those tracking discrepancies in climate science, this is worth a closer look.<\/p>\n\n\n\n

The researchers analyzed satellite data spanning 1988 to 2017, drawing from four independent products: J-OFURO3, SeaFlux, HOAPS, and IFREMER. Their findings show that global ocean evaporation\u2014which supplies about 85% of the atmosphere\u2019s water vapor\u2014rose sharply over the first two decades of the period, peaking around 2008. Then, the trend flipped. From 2008 to 2017, the global average dipped slightly, with two-thirds of the ocean experiencing reduced evaporation. This was validated, where possible, against buoy observations from the Global Tropical Moored Buoy Array, though coverage is sparse beyond the tropics.<\/p>\n\n\n\n

\n

Abstract<\/h2>\n\n\n\n

Ocean evaporation (E<\/em>o<\/sub>) is the major source of atmospheric water vapor and precipitation. While it is widely recognized that E<\/em>o<\/sub> may increase in a warming climate, recent studies have reported a diminished increase in the global water vapor since \u223c2000s, raising doubts about recent changes in E<\/em>o<\/sub>. Using satellite observations, here we show that while global E<\/em>o<\/sub> strongly increased from 1988 to 2017, the upward trend reversed in the late 2000s. Since then, two-thirds of the ocean have experienced weakened evaporation, leading to a slight decreasing trend in global-averaged E<\/em>o<\/sub> during 2008\u20132017. This suggests that even with saturated surface, a warmer climate does not always result in increased evaporation. The reversal in E<\/em>o<\/sub> trend is primarily attributed to wind stilling, which is likely tied to the Northern Oscillation Index shifting from positive to negative phases. These findings offer crucial insights into diverse responses of global hydrological cycle to climate change.

https:\/\/agupubs.onlinelibrary.wiley.com\/doi\/10.1029\/2024GL114256<\/a><\/p>\n<\/blockquote>\n\n\n\n

What\u2019s driving this? The study points to \u201cwind stilling\u201d\u2014a measurable drop in near-surface wind speeds, particularly pronounced in the Southern Hemisphere. They link this to the Northern Oscillation Index (NOI), a measure of pressure differences between the North Pacific High and near Darwin, Australia, shifting from positive to negative phases after 2008. This phase change aligns with weakened trade winds and a broader slowdown in atmospheric circulation, outweighing the evaporation boost expected from rising sea surface temperatures (SSTs).<\/p>\n\n\n\n

This challenges a core assumption in climate science: that evaporation scales predictably with temperature via the Clausius-Clapeyron relationship, where warmer air holds more vapor and thus pulls more water from the surface. The study\u2019s data shows SSTs climbing as expected, increasing the air-sea humidity deficit\u2014a key driver of evaporation. Yet wind speed\u2019s decline overpowered that effect, cutting evaporation anyway. The authors quantify this using a multiple regression model, finding wind speed accounted for 62% of the post-2008 drop, compared to 38% from humidity changes.<\/p>\n\n\n\n

The ramifications are significant. First, a weaker evaporation signal could reduce the moisture feeding precipitation, especially for land regions relying on ocean-derived vapor. The study notes spatial variation\u2014declines were strongest in the southern tropical Pacific, Indian Ocean, and extratropical Atlantic\u2014suggesting uneven impacts on rainfall patterns. Second, it could alter ocean salinity trends. Evaporation typically concentrates salt at the surface, but a slowdown might ease that process, particularly in subtropical zones where it dominates over precipitation. This could subtly influence density-driven ocean currents, though the study doesn\u2019t claim dramatic shifts like an Atlantic Meridional Overturning Circulation disruption.<\/p>\n\n\n\n

For climate modeling, this is a wrinkle. Most global circulation models (GCMs) project an intensified hydrological cycle under warming\u2014more evaporation, more rain, more extremes. But if wind speed can override temperature effects, those projections might overshoot reality. The authors frame this as a possible natural cycle tied to decadal oscillations like the NOI or Pacific Decadal Oscillation, not a permanent climate change signature. Still, they leave the door open: if human-driven warming (e.g., polar amplification) is quietly slowing winds, this could signal a longer-term shift. With data ending in 2017, we\u2019re stuck waiting for updates to settle that question.<\/p>\n\n\n\n

Uncertainties linger. The satellite datasets aren\u2019t flawless\u2014HOAPS, for instance, shows a steeper drop, possibly due to quirks in its microwave sensor platforms (SSMI\/SSMIS), while the others temper that signal by blending multiple sources. Buoy validation helps, but it\u2019s spotty outside tropical zones, leaving high-latitude trends less certain. The study also sidesteps intra-annual shifts and secondary drivers like radiation or upwelling, focusing narrowly on wind and humidity. Future work, they suggest, could refine this with better measurements\u2014think next-gen satellites or ocean drones.<\/p>\n\n\n\n

It\u2019s another case where observations don\u2019t match the script. The \u201cwarming equals wetter\u201d narrative takes a hit when a natural factor like wind can call the shots. It\u2019s not a knockout blow to climate orthodoxy\u2014evaporation rose for decades before 2008, tracking warming\u2014but it exposes gaps in the models and the risk of over-relying on simplified physics. Is this a strong indicator that atmospheric dynamics are more in charge than CO2-driven forecasts admit? The study doesn\u2019t preach; it just lays out the numbers. That\u2019s plenty of fuel for discussion.<\/p>\n\n\n\n

[Link to study: https:\/\/agupubs.onlinelibrary.wiley.com\/doi\/10.1029\/2024GL114256]<\/a><\/p>\n\n\n\n

H\/T Dr. Judith Curry<\/p>\n\n\n\n

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

A recent study published in\u00a0Geophysical Research Letters, has turned up a surprising result: global ocean evaporation, a cornerstone of the hydrological cycle, has been declining since the late 2000s despite steadily warming sea surfaces. This runs counter to the widely held view that a warmer climate should boost evaporation rates. For those tracking discrepancies in climate science, this is worth a closer look.<\/p>\n","protected":false},"author":121246920,"featured_media":367695,"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_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":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":[691833550,691818153,691828806,691833548,691833549,691826905],"class_list":["post-367691","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-atlantic-meridional-overturning-circulation","tag-climate-models","tag-global-circulation-models-gcms","tag-global-ocean-evaporation","tag-northern-oscillation-index-noi","tag-sea-surface-temperatures-ssts","fallback-thumbnail"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/02799633.webp?fit=1920%2C1080&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-1xEv","jetpack-related-posts":[{"id":367538,"url":"https:\/\/climatescience.press\/?p=367538","url_meta":{"origin":367691,"position":0},"title":"New Study: Ocean Warming Is Supposed to Increase Water Vapor \u2013 But It\u2019s Been Declining Since 2008","author":"uwe.roland.gross","date":"02\/25\/2025","format":false,"excerpt":"\u201cOur findings are unexpected: despite rising sea surface temperatures, global Eo [ocean evaporation\/water vapor] has decreased in the most recent decade.\u201d \u2013 Ma et al., 2025","rel":"","context":"In \"Climate models\"","block_context":{"text":"Climate models","link":"https:\/\/climatescience.press\/?tag=climate-models"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0process-water-vapour-atmosphere-video.webp?fit=1200%2C675&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0process-water-vapour-atmosphere-video.webp?fit=1200%2C675&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0process-water-vapour-atmosphere-video.webp?fit=1200%2C675&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0process-water-vapour-atmosphere-video.webp?fit=1200%2C675&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0process-water-vapour-atmosphere-video.webp?fit=1200%2C675&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":441135,"url":"https:\/\/climatescience.press\/?p=441135","url_meta":{"origin":367691,"position":1},"title":"Why Climate Models Get Ocean Warming Patterns Wrong: They Exaggerate Greenhouse Gas Effects on the Hemispheres","author":"uwe.roland.gross","date":"04\/24\/2026","format":false,"excerpt":"Climate models and ocean observations diverge primarily on the pattern of hemispheric ocean warming\u2014specifically, the interhemispheric thermal contrast (IHTC), or the difference in average sea surface temperature (SST) between the Northern and Southern Hemispheres. 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