{"682820":{"#nid":"682820","#data":{"type":"news","title":"Ocean \u2018Greening\u2019 at Poles Could Spell Changes for Fisheries","body":[{"value":"\u003Cp\u003EOcean waters are getting greener at the poles and bluer toward the equator, according to an analysis of satellite data published in \u003Cem\u003EScience\u003C\/em\u003E on June 19. The change reflects shifting concentrations of a green pigment called chlorophyll made by phytoplankton, photosynthetic marine organisms at the base of the ocean food chain. If the trend continues, marine food webs could be affected, with potential repercussions for global fisheries.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u201cIn the ocean, what we see based on satellite measurements is that the tropics and the subtropics are generally losing chlorophyll, whereas the polar regions \u2014 the high-latitude regions \u2014 are greening,\u201d says first author\u0026nbsp;\u003Cstrong\u003EHaipeng Zhao\u003C\/strong\u003E, a postdoctoral researcher at \u003Ca href=\u0022https:\/\/www.gatech.edu\/\u0022\u003EGeorgia Tech\u003C\/a\u003E working with \u003Cstrong\u003ESusan Lozier\u003C\/strong\u003E, dean of the \u003Ca href=\u0022https:\/\/cos.gatech.edu\/\u0022\u003ECollege of Sciences\u003C\/a\u003E and Betsy Middleton and John Sutherland Chair at Georgia Tech and \u003Cstrong\u003ENicolas Cassar\u003C\/strong\u003E, the Lee Hill Snowdon Bass Chair at \u003Ca href=\u0022https:\/\/duke.edu\/\u0022\u003EDuke University\u003C\/a\u003E\u2019s \u003Ca href=\u0022https:\/\/nicholas.duke.edu\/\u0022\u003ENicholas School of the Environment\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003ESince the 1990s, many studies have documented enhanced greening on land, where global average leaf cover is increasing due to rising temperatures and other factors. But documenting photosynthesis across the ocean has been more difficult, according to the team. Although satellite images can provide data on chlorophyll production at the ocean\u2019s surface, the picture is incomplete.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EThe study analyzed satellite data collected from 2003 to 2022 by a NASA instrument that combs the entire Earth every two days, measuring light wavelength. The researchers were looking for changes in chlorophyll concentration, a proxy for phytoplankton biomass. For consistency, they focused on the open ocean and excluded data from coastal waters.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u201cThere are more suspended sediments in coastal waters, so optical properties are different than in the open ocean,\u201d Zhao explains. \u0026nbsp;\u003C\/p\u003E\u003Cp\u003EThe satellite data revealed broad trends in color, indicating that chlorophyll is decreasing in subtropical and tropical regions and increasing toward the poles. Building on that finding, the team examined how chlorophyll concentration is changing at specific latitudes. To work around background noise and gaps in data, they had to get creative.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u201cWe borrowed concepts from economics called the Lorenz curve and the Gini index, which together show how wealth is distributed in a society. So, we thought, let\u2019s apply these to see whether the proportion of the ocean that holds the most chlorophyll has changed over time,\u201d Cassar says.\u003C\/p\u003E\u003Cp\u003EThey found similar but opposing trends in chlorophyll concentration over the two-decade period. Green areas became greener, particularly in the northern hemisphere, while blue regions got even bluer.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u201cIt\u2019s like rich people getting richer and the poor getting poorer,\u201d Zhao says.\u003C\/p\u003E\u003Cp\u003ENext, the team examined how the patterns they observed were affected by several variables, including sea surface temperature, wind speed, light availability and mixed layer depth \u2014 a measure that reflects mixing in the ocean\u2019s top layer by wind, waves and surface currents. Warming seas correlated with changes in chlorophyll concentration, but the other variables showed no significant associations.\u003C\/p\u003E\u003Cp\u003EThe authors cautioned that their findings cannot be attributed to climate change.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u201cThe study period was too short to rule out the influence of recurring climate phenomena such as El Ni\u00f1o,\u201d Lozier says. \u201cHaving measurements for the next several decades will be important for determining influences beyond climate oscillations.\u201d\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EIf poleward shifts in phytoplankton continue, however, they could affect the global carbon cycle. During photosynthesis, phytoplankton act like sponges, soaking up carbon dioxide from the atmosphere. When these organisms die and sink to the ocean bottom, carbon goes down with them. The location and depth of that stored carbon can influence climate warming.\u003C\/p\u003E\u003Cp\u003E\u201cIf carbon sinks deeper or in places where water doesn\u2019t resurface for a long time, it stays stored much longer. In contrast, shallow carbon can return to the atmosphere more quickly, reducing the effect of phytoplankton on carbon storage,\u201d Cassar says.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EAdditionally, a persistent decline in phytoplankton in equatorial regions could alter fisheries that many low- and middle-income nations, such as those in the Pacific Islands, rely on for food and economic development \u2014 especially if that decline carries over to coastal regions, according to the authors.\u003C\/p\u003E\u003Cp\u003E\u201cPhytoplankton are at the base of the marine food chain. If they are reduced, then the upper levels of the food chain could also be impacted, which could mean a potential redistribution of fisheries,\u201d Cassar says.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EFunding:\u0026nbsp;\u003C\/em\u003ENational Science Foundation and NASA.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003ECitation\u003C\/em\u003E: \u201c\u003Ca href=\u0022https:\/\/www.eurekalert.org\/tipsheet\/science_family_tipsheet#.\u0022 title=\u0022View Details\u0022\u003EGreener green and bluer blue: Ocean poleward greening over the past two decades\u003C\/a\u003E,\u201d\u0026nbsp;Zhao H., Manizza M., Lozier S.M. and Cassar N. \u003Cem\u003EScience\u003C\/em\u003E, June 19, 2025, DOI: \u003Ca href=\u0022https:\/\/doi.org\/10.1126\/science.adr9715\u0022 target=\u0022_blank\u0022\u003E10.1126\/science.adr9715\u003C\/a\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis story by Julie Leibach is shared with the Duke University Nicholas School of the Environment newsroom.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EOcean waters are getting greener at the poles and bluer toward the equator, according to an analysis of satellite data published in \u003Cem\u003EScience\u003C\/em\u003E. The change reflects shifting concentrations of chlorophyll made by phytoplankton. If the trend continues, marine food webs could be affected, with potential impacts on fisheries near the equator and carbon sequestration near the poles.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Ocean waters are getting greener at the poles and bluer toward the equator, according to an analysis of satellite data published in Science on June 19. "}],"uid":"34528","created_gmt":"2025-06-19 16:38:20","changed_gmt":"2025-06-19 18:16:34","author":"jhunt7","boilerplate_text":"","field_publication":"","field_article_url":"","location":"Atlanta, GA","dateline":{"date":"2025-06-19T00:00:00-04:00","iso_date":"2025-06-19T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"677252":{"id":"677252","type":"image","title":"A satellite image of blooming phytoplankton, visible as green-tinted swirls, in the South Atlantic. Credit: NASA Credit: NASA (OCI sensor aboard PACE on January 5, 2025)","body":"\u003Cp\u003EA satellite image of blooming phytoplankton, visible as green-tinted swirls, in the South Atlantic. Credit: NASA (OCI sensor aboard PACE on January 5, 2025)\u003C\/p\u003E","created":"1750351382","gmt_created":"2025-06-19 16:43:02","changed":"1750351382","gmt_changed":"2025-06-19 16:43:02","alt":"A satellite image of blooming phytoplankton, visible as green-tinted swirls, in the South Atlantic. Credit: NASA","file":{"fid":"261134","name":"NASA---satellite.jpg","image_path":"\/sites\/default\/files\/2025\/06\/19\/NASA---satellite.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2025\/06\/19\/NASA---satellite.jpg","mime":"image\/jpeg","size":10017003,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2025\/06\/19\/NASA---satellite.jpg?itok=hOH8GmRd"}}},"media_ids":["677252"],"groups":[{"id":"1278","name":"College of Sciences"},{"id":"565971","name":"Ocean Science and Engineering (OSE)"},{"id":"1188","name":"Research Horizons"},{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"187915","name":"go-researchnews"},{"id":"194597","name":"poleward greening"},{"id":"176359","name":"oceans"},{"id":"2262","name":"climate"},{"id":"193266","name":"cos-research"},{"id":"192254","name":"cos-climate"},{"id":"180514","name":"Susan Lozier"},{"id":"194598","name":"Haipeng Zhao"},{"id":"166926","name":"School of Earth and Atmospheric Sciences"}],"core_research_areas":[{"id":"194566","name":"Sustainable Systems"}],"news_room_topics":[{"id":"71911","name":"Earth and Environment"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003EMedia Contacts:\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jess@cos.gatech.edu\u0022\u003EJess Hunt-Ralston\u003C\/a\u003E\u003Cbr\u003EDirector of Communications\u003Cbr\u003ECollege of Sciences\u0026nbsp;\u003Cbr\u003EGeorgia Tech\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:julie.leibach@duke.edu\u0022\u003EJulie Leibach\u003C\/a\u003E\u0026nbsp;\u003Cbr\u003ESenior Science Writer\u003Cbr\u003ENicholas School of the Environment\u003Cbr\u003EDuke University\u0026nbsp;\u003C\/p\u003E","format":"limited_html"}],"email":["jess@cos.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}