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Ocean ‘Greening’ at Poles Could Spell Changes for Fisheries

admin — Thu, 19 Jun 2025 18:16:41 +0000

Ocean ‘Greening’ at Poles Could Spell Changes for Fisheries admin Thu, 06/19/2025 - 14:16

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. 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.

“In the ocean, what we see based on satellite measurements is that the tropics and the subtropics are generally losing chlorophyll, whereas the polar regions — the high-latitude regions — are greening,” says first author Haipeng Zhao, a postdoctoral researcher at Georgia Tech working with Susan Lozier, dean of the College of Sciences and Betsy Middleton and John Sutherland Chair at Georgia Tech and Nicolas Cassar, the Lee Hill Snowdon Bass Chair at Duke University’s Nicholas School of the Environment.

Since 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’s surface, the picture is incomplete.

The 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.

“There are more suspended sediments in coastal waters, so optical properties are different than in the open ocean,” Zhao explains.

The 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.

“We 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’s apply these to see whether the proportion of the ocean that holds the most chlorophyll has changed over time,” Cassar says.

They 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.

“It’s like rich people getting richer and the poor getting poorer,” Zhao says.

Next, 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 — a measure that reflects mixing in the ocean’s top layer by wind, waves and surface currents. Warming seas correlated with changes in chlorophyll concentration, but the other variables showed no significant associations.

The authors cautioned that their findings cannot be attributed to climate change.

“The study period was too short to rule out the influence of recurring climate phenomena such as El Niño,” Lozier says. “Having measurements for the next several decades will be important for determining influences beyond climate oscillations.”

If 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.

“If carbon sinks deeper or in places where water doesn’t 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,” Cassar says.

Additionally, 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 — especially if that decline carries over to coastal regions, according to the authors.

“Phytoplankton 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,” Cassar says.

Funding: National Science Foundation and NASA.

Citation: “Greener green and bluer blue: Ocean poleward greening over the past two decades,” Zhao H., Manizza M., Lozier S.M. and Cassar N. Science, June 19, 2025, DOI: 10.1126/science.adr9715

This story by Julie Leibach is shared with the Duke University Nicholas School of the Environment newsroom.

Summary sentence

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.

Summary

Ocean waters are getting greener at the poles and bluer toward the equator, according to an analysis of satellite data published in Science. 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.

Dateline

Thu, 06/19/2025 - 12:00

jess@cos.gatech.edu

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Media Contacts:

Jess Hunt-Ralston
Director of Communications
College of Sciences
Georgia Tech

Julie Leibach
Senior Science Writer
Nicholas School of the Environment
Duke University

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Thu, 06/19/2025 - 14:16

James Stroud Named Early Career Fellow by Ecological Society of America

admin — Tue, 30 Apr 2024 16:34:41 +0000

James Stroud Named Early Career Fellow by Ecological Society of America admin Tue, 04/30/2024 - 12:34

James T. Stroud has been named an Early Career Fellow by the Ecological Society of America.

He joins the ranks of nine newly appointed ESA Fellows and ten 2024-2028 ESA Early Career Fellows, elected for "advancing the science of ecology and showing promise for continuing contributions" and recently confirmed by the organization's Governing Board.

Stroud, an Elizabeth Smithgall Watts Early Career Assistant Professor in the School of Biological Sciences, is an integrative evolutionary ecologist who investigates how ecological and evolutionary processes may underlie patterns of biological diversity at the macro-scale.

He primarily studies lizards and his research is highly multidisciplinary, combining field studies with macro-ecological and evolutionary comparative analyses. Stroud’s current interests are particularly focused on measuring natural selection in the wild, often taking advantage of non-native lizards as natural experiments in ecology and evolution.

Earlier this month, Stroud presented his recent work at the inaugural College of Sciences Frontiers in Science: Climate Action Conference and Symposium, joining more than 20 faculty experts and 100 stakeholders from across all six colleges at Georgia Tech to discuss climate change, challenges, and solutions.

Stroud joined the Georgia Tech faculty in August 2023. He earned a Ph.D. in Ecology and Evolution from Florida International University.

"I am thrilled to recognize the exceptional contributions of our newly selected Fellows and Early Career Fellows,” says ESA President Shahid Naeem. “Their groundbreaking research, unwavering commitment to mentoring and teaching and advocacy for sound science in management and policy decisions have not only advanced ecological science but also inspired positive change within our community and beyond. We celebrate their achievements and eagerly anticipate the profound impacts they will continue to make in their careers."

ESA will formally acknowledge and celebrate its new Fellows for their exceptional achievements during a ceremony at ESA’s 2024 Annual Meeting in Long Beach, California.

About ESA Fellowships

ESA established its Fellows program in 2012 with the goal of honoring its members and supporting their competitiveness and advancement to leadership positions in the Society, at their institutions, and in broader society. Past ESA Fellows and Early Career Fellows are listed on the ESA Fellows page.

About ESA

The Ecological Society of America, founded in 1915, is the world’s largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 8,000 member Society publishes six journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society’s Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at https://www.esa.org.

Summary sentence

Stroud joins nine newly appointed Fellows and ten ESA Early Career Fellows, elected for "advancing the science of ecology and showing promise for continuing contributions" in the field.

Summary

Stroud, an Elizabeth Smithgall Watts Early Career Assistant Professor in the School of Biological Sciences, joins nine newly appointed Fellows and ten Early Career Fellows, elected for "advancing the science of ecology and showing promise for continuing contributions" in the field.

Dateline

Tue, 04/30/2024 - 12:00

jess@cos.gatech.edu

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Jess Hunt-Ralston
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College of Sciences at Georgia Tech

Mayda Nathan
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As Temperatures Climb, Flying Insects Slower to Migrate to Cooler Elevations

admin — Mon, 11 Sep 2023 21:56:31 +0000

As Temperatures Climb, Flying Insects Slower to Migrate to Cooler Elevations admin Mon, 09/11/2023 - 17:56

This story by Jennifer Woodruff is shared jointly with the University of Colorado Denver.

In response to rising global temperatures, many plants and animals are moving to higher elevations to survive in cooler temperatures. But a new study from the University of Colorado Denver (CU Denver) and Georgia Tech finds that for flying insects — including bees and moths — this escape route may have insurmountable issues that could mean their doom.

The research team examined more than 800 species of insects from around the world and discovered that many winged insects are moving to higher elevations much slower than their non-flying counterparts. This is because the thinner air at higher elevations provides less oxygen for species to use. Because flight requires more oxygen to generate energy for movement than other styles of movement, such as walking, these species are migrating more slowly.

The team’s findings were published in this week’s Nature Climate Change journal. Jesse Shaich, postbaccalaureate student at CU Denver, is also a member of the research team.

“When we think about where species will be able to live under climate change in the coming decades, we need to remember that animals are sensitive to more than just how hot or cold they are,” said CU Denver Assistant Professor of Integrated Biology Michael Moore, who led the study.

Declining insect biodiversity has direct impact on humans

If flying insects’ native habitats get too warm too quickly, and they can’t find a suitable alternative or adapt in time, that will likely lead to their extinction. Beyond just being bad for the bugs themselves, loss of insects is bad news for humans as well. Most crop pollinators are the flying species the researchers expect to be vulnerable, and their extinction would be catastrophic to global food supply. Not only would this have implications for agriculture and food supply chains, but similar challenges are likely true for other species that need a lot of oxygen to live.

“Our earth’s biodiversity is rapidly declining, especially amongst insects. The global loss of insects will be ecologically catastrophic, so we urgently need to understand why and how this is happening,” said James Stroud, assistant professor of Biological Sciences at Georgia Tech.

Broadening research on high elevation challenges

To conserve as many species as possible, researchers need to grasp the full scope of challenges plants and animals face, whether they can overcome these challenges, and to predict the locations where they can survive. High elevation environments are also difficult for new species because of the scarcity of food, stronger winds, more extreme cold snaps, and increased ultraviolet radiation.

Moore concludes, “If we want to design effective conservation strategies, we must consider a broader range of environmental factors that species need to live.”

About Georgia Institute of Technology
The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 45,000 undergraduate and graduate students, representing 50 states and more than 148 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

About the University of Colorado Denver
The University of Colorado Denver is the state’s premier public urban research university and equity-serving institution. Globally connected and locally invested, CU Denver partners with future-focused learners and communities to design accessible, relevant, and transformative educational experiences for every stage of life and career. Across seven schools and colleges in the heart of downtown Denver, our leading faculty inspires and works alongside students to solve complex challenges through boundary-breaking innovation, impactful research, and creative work. As part of the state’s largest university system, CU Denver is a major contributor to the Colorado economy, with 2,000 employees and an annual economic impact of $800 million. For more information, visit ucdenver.edu.

https://doi.org/10.1038/s41558-023-01794-2

Acknowledgments: Support was generously provided by the University of Colorado Denver (to M.P.M. and J.S.) and Washington University in St. Louis and the Georgia Institute of Technology (to J.T.S.). Conversations with J. de Mayo, J. Grady and A. Lenard and input from three reviewers improved this study.

Subtitle

Flying insects like bees and moths struggle with low oxygen and thin air at high elevations.

Summary sentence

In response to changing climates, many plants and animals are moving to higher elevations, seeking cooler temperatures. But a new study finds that flying insects like bees and moths may struggle with insurmountable issues to this escape route.

Summary

In response to changing climates, many plants and animals are moving to higher elevations, seeking cooler temperatures. But a new study from Georgia Tech and the University of Colorado Denver finds that flying insects like bees and moths may struggle with insurmountable issues to this escape route.

Dateline

Mon, 09/11/2023 - 12:00

jess@cos.gatech.edu

Contact

Jess Hunt-Ralston
Director of Communications
College of Sciences at Georgia Tech
jess@cos.gatech.edu

Jennifer Woodruff
Director of Public Relations & Integrated Media
University of Colorado Denver
Jennifer.Woodruff@ucdenver.edu
+1 (303) 315-0283

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Vice President’s Visit Brings Climate Change Discussion to Forefront

admin — Thu, 09 Feb 2023 19:52:53 +0000

Vice President’s Visit Brings Climate Change Discussion to Forefront admin Thu, 02/09/2023 - 14:52

With the Ferst Center filled to the brim Wednesday, Georgia Tech hosted Vice President Kamala Harris for a discussion about the climate crisis, which she called a transformational moment in America.

Speaking on the “moment of great opportunity” in the face of the equally daunting challenge of the climate crisis, Harris participated in a moderated discussion at the Ferst Center for the Arts on the Georgia Tech campus Wednesday afternoon.

The vice president spoke to students, faculty, staff, and community members with the message of creating an equitable clean energy economy and how it will take a true team effort to achieve that goal.

“In order for us to truly achieve that, it’s going to require all to be involved … our scientists, our researchers, our academicians,” she said. “But it’s also going to be about our students. It’s going to be about our unions. It’s going to be about the private sector. It’s going to be about our teachers. It’s going to be about our youth leaders. It is going to take a whole community.”

Continuing Georgia Tech’s longstanding tradition of hosting elected officials, going back to 1905 with President Theodore Roosevelt, Harris was joined by Isaiah Bolden, assistant professor in the School of Earth and Atmospheric Sciences, and James Marshall Shepherd, director of the Atmospheric Sciences Program at the University of Georgia. Each spoke of how their life experiences led them to their respective career paths.

Bolden’s passion for climate science was born out of tragedy as he saw his hometown of Nashville, Tennessee, flooded. Seeing the number of people and entire communities that were displaced, Bolden shared that his career choice became clear in that moment.

“I had this passion burgeoning right then and there as someone who has this aptitude for science, this aptitude for math, but then seeing that the science is not reaching the public in a way that it should,” he said. “What can I then do with my career as an environmental scientist to generate data and get that data into the hands of people who could do something with it?”

Perhaps the most visible sign of a movement toward the country’s recent commitment to climate change efforts is the increased number of electric vehicles on roadways. With Georgia positioning itself as a leader in that sector by attracting manufacturers such as Hyundai, Rivian, and Qcells to the state, Georgia Tech President Ángel Cabrera emphasized that the campus in the heart of Atlanta was the “perfect place” to host Wednesday’s discussion.

“As one of the nation’s leading research universities, Georgia Tech is committed to making sure that our $1.3 billion research enterprise, our unmatched faculty expertise, and our top students help in this process by producing new solutions and exceptional talent while driving economic opportunity through job creation,” he said.

In addition to community resilience policies that focus on removing lead pipes in cities across the country and other funding created through the Inflation Reduction Act and the Infrastructure Investment and Jobs Act, Harris spoke passionately about the electrification of school buses.

Currently, 90% of the buses that carry 25 million children to school daily are diesel-fueled. Along with the public health and environmental impact of electrifying buses, Harris touted the prospect of creating new jobs and new manufacturing opportunities.

As the climate conversation continues, Shepherd emphasized that these are “kitchen table issues” that affect everyone. Harris reiterated that point, noting that the discussion serves as an intersection for environmental justice and equity in public health and education before closing with a message to the next generation of leaders.

“You are coming out and we’re talking about all kinds of creative, very exciting ways to do this that are going to be about public health, public education, strengthening our economy, investing in jobs, respecting the dignity of work, being a model for the world, and being a good shepherd of resources, both in terms of the responsibility that America has to Americans and that America has to its neighbors,” she said.

Joe Bozeman III, assistant professor in the School of Civil and Environmental Engineering whose work as an industrial ecologist highlights the need for equitable climate change adaptation and mitigation strategies, left the Ferst Center with a sense that the discussion around climate policy is moving into the forefront.

“Seeing the vice president speak so confidently and expansively about the issue of climate justice, equity, and the engineering side of things, I really found myself impressed,” Bozeman said. “I feel more confident about the administration’s intent behind some of the acts they’ve passed, and I’m enthused to continue to do the work as a researcher here at Georgia Tech.”

He also noted how the vice president’s visit serves as a reminder of Georgia Tech’s important role in the community and how the campus serves as a place for collaboration.

“The HBCU representation here, in particular, was exciting for me to see. And my hope is that we can continue to make some of the internal efforts connecting with our HBCUs and our other minority serving institutions and come up with the kind of innovative, inclusive solutions that may have eluded us 10 or 20 years before,” he said.

Summary sentence

With the Ferst Center filled to the brim Wednesday, Georgia Tech hosted Vice President Kamala Harris for a discussion about the climate crisis, which she called a transformational moment in America.

Summary

<p>With the Ferst Center filled to the brim Wednesday, Georgia Tech hosted Vice President Kamala Harris for a discussion about the climate crisis, which she called a transformational moment in America.</p>

Dateline

Thu, 02/09/2023 - 12:00

Contact

Steven Gagliano

Communications Officer

Institute Communications

Past Presidential Visits to Georgia Tech

President Theodore Roosevelt
October 20, 1905

President-Elect William H. Taft
January 16, 1909

President Franklin D. Roosevelt
November 29, 1935

President Jimmy Carter
February 20 and August 30, 1979

President William J. Clinton
July 19, 1996

President George W. Bush
March 27, 2002

President Barack Obama
March 10, 2015

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Ocean ‘Greening’ at Poles Could Spell Changes for Fisheries

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As Temperatures Climb, Flying Insects Slower to Migrate to Cooler Elevations

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Vice President’s Visit Brings Climate Change Discussion to Forefront

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