The Cascadia Subduction Zone is unusually quiet for a megathrust fault. Spanning more than 600 miles from Canada to California, the fault marks the convergence of the Juan de Fuca and North American plates. While other subduction zones produce sporadic rumblings as the plates scrape past each other, Cascadia , fueling assumptions that the plates are locked together by friction.

The subduction zone — miles offshore and deep underwater — is difficult to observe. Most data collection is based onshore, which limits the breadth and quality of results. The lack of earthquakes further complicates efforts to understand its behavior and structure.

In a new study, the first to monitor strain offshore for an extended period of time, 91̽�� researchers report that the plates may not be fully locked. Based on 13 years of ground motion data from sensors in different regions, the study shows the northern portion of the fault is locked and quiet, but the central region appears to be more active. There, researchers observed signs of a shallow, slow-motion earthquake and detected pulses of fluid flowing through subterranean channels, which may relieve pressure from the fault.

The findings, , may alter expectations of how this area will respond to a large earthquake. Similar features in other places have stopped a rupture that might have otherwise continued along the entire fault line.

“It’s preliminary, but we think that variable fluid pathways in Cascadia will change the behavior of large earthquakes on the fault,” said co-author , a 91̽��associate professor of Earth and space science.

The Juan de Fuca plate is advancing toward the North American plate at a rate of . But because the plates are stuck together, that motion generates pressure. Eventually, the building tension will exceed what the plates can tolerate. When they eventually slip free, an earthquake will spread along the boundary.

Megathrust earthquakes, which occur at boundaries where one plate slides beneath another, rock the Pacific Northwest every 500 or so years. one to 1700, and estimates suggest a 10 to 15% chance that the entire fault will rupture, producing an earthquake that could exceed magnitude 9, within the next fifty years. The results from this study do not alter those odds, but the dynamics captured might influence the severity of the eventual earthquake.

A recent survey of the seafloor found that into at least four geologically distinct segments. Each one may be insulated from a rupture in another region. In this study, the researchers took a closer look at two of the regions by analyzing data from three monitoring stations, one near Vancouver Island and two off the coast of Oregon.

“We wanted to understand strain changes in different regions offshore,” said lead author , a 91̽��doctoral student of oceanography. “We used the seismometers to measure how the seismic velocity varies underneath each station.”

Seismic velocity is a term used to describe the rate at which ambient noise travels through a material. Because the speed of sound depends on what it is moving through, tracking seismic velocity can give researchers a window into processes occurring beneath the ocean floor.

“When you compact something, you can expect the sound waves to move through it faster,” said Kidiwela.

The steady increase in seismic velocity observed at the northern site told the researchers the rock was compacting, which supports the theory that the two plates are locked in place.

The central region displayed a different pattern. For two months in 2016, seismic velocity decreased. The researchers attribute this drop to a slow-motion earthquake on the shallow edge of the oceanic plate that relieved some of the pressure at the fault.

Other drops in seismic velocity, recorded between 2017 and 2022, were linked to fluid dynamics. Subduction squeezes liquid out of rocks and pushes it toward the surface. The study found that other faults, running perpendicular to the subduction zone, may act as pathways for letting trapped fluid out.

“During a megathrust rupture, one of the ways that an earthquake propagates is through fluid pressure. If you have a way to release these fluids, it could help improve the stability of the fault, and potentially impact how the region behaves during a large earthquake,” Kidiwela said.

Pulling data from just three sites, the researchers observed complex dynamics that may have gone overlooked. Future work will greatly expand this effort. in 2023 to build an underwater observatory in the Cascadia Subduction Zone.

“Finding this link between fluids coming to the shallow subduction zone is pretty unique, as is the evidence that the fault is not completely locked,” said co-author , a 91̽��professor of oceanography and one of the scientists involved with the observatory. “It suggests that we need more instruments there, because there may be more going on than people have been able to figure out before.”

Additional co-authors include from the University of Utah.��

This study was funded by the Jerome M. Paros Endowed Chair in Sensor Networks at the 91̽�� and the National Science Foundation.��

For more information, contact Kidiwela at seismic@uw.edu.

The earthquake that rocked Alaska for close to five minutes on March 27, 1964, in U.S. history. It registered a magnitude of 9.2 on the Richter scale and generated a tsunami that killed people as far south as California. The earthquake also changed the nature of the land surrounding its epicenter near Prince William Sound.

Now, researchers from the 91̽��, led by , an assistant professor of oceanography at UW, the University of Rhode Island and the Desert Research Institute are traveling to Anchorage and the Copper River Delta to study marshes that formed in the years following the earthquake. Few geomorphologists have been to this region, and no one has compared the Alaskan marshes to those in more temperate regions. The ecological implications are significant for local wildlife and Alaskan communities.

Valentine has spearheaded similar interdisciplinary projects at the Willapa salt marsh in Washington with the goal of understanding how the ecosystem is adapting to climate change. In Alaska, she will co-lead a team of five early career researchers, and they will capture video and photos throughout their trip.

Valentine answered a few questions about her work for the occasional series “In the Field,” which highlights 91̽��field efforts.

Tell us about the trip. Where are you going and why?

Kendall Valentine: We are heading to two primary areas – Anchorage and the Copper River Delta – to investigate salt marsh morphodynamics, which is another way of saying landscape-scale changes. We want to understand what happens along the coast after large seismic events.

The 1964 Alaska earthquake lifted the mudflats upward by several meters, creating a suitable environment for marsh vegetation where there wasn’t one before. Marshes rapidly formed, and rough estimates indicate that one to three meters of marsh sediments have accumulated in these areas since. Our understanding of how marshes form and function is based on slow-moving landscapes on passive margins, or places that don’t experience earthquakes. Studying these sites in Alaska will allow us to re-envision marsh dynamics.

The Copper River Delta is also one of the largest deltas in North America, but it is grossly understudied. Deltas form when fast moving water, such as a river, meets a slower body of water, like the sea. Fresh water, saltwater and mud all mix, which creates a dynamic environment and unique habitats. And, as the mud settles, it traps carbon.

What do you and your team hope to learn?

KV: High-latitude wetlands like these are experiencing rapid changes as sea levels rise, permafrost thaws and seasonal ice cover shifts. Erosion rates are increasing, which will influence the landscape and rates of carbon sequestration. These wetlands are critical for wildlife, coastline protection, trapping pollutants, managing nutrient distribution and storing carbon, but there is a real dearth of information about their geomorphology and ecology. We are pioneering the study of seasonally thawed, tectonically active marshes. Researchers have reported a “staggering lack of information” on shorelines at high latitudes, despite their abundance. These often-remote sites are hard to access, working conditions can be harsh and there are few cities nearby. We will be taking an airboat to remote locations to collect core samples and analyze carbon storage, sediment accumulation rates and more.

We hypothesize that carbon storage in high-latitude Alaskan marshes is driven by tectonic history, and we will explore the local carbon dynamics and note how plant populations have changed and marsh geography has evolved. Changes to the marsh could threaten infrastructure, coastal communities and cultural traditions and cost the state billions of dollars in maintenance and repairs.

Who else is going?

KV: I am going with , a graduate student in at UW;, an assistant professor in oceanography at the University of Rhode Island; , a graduate student in her lab Erin Peck’s lab; and , a postdoctoral researcher at the Desert Research Institute. My portion of this project is funded by the Quaternary Research Center here at UW.

We will also venture out into the field with some local partners. Ryan Choi, a vegetation and wetland ecologist in the at the University of Alaska Anchorage�� will join us, and his group has been very supportive. He will be exploring beaver impacts at the same sites.

We are also partnering with the U.S. Forest Service at the Chugach National Forest, who will provide field support (such as boats and bear protection) for the Copper River Delta work.

What do you enjoy about doing field work that might not occur to most people?

KV: What I love most about field work is connecting with the landscape. Marshes are very flat and wide. When you stand in one, particularly like the ones in Alaska – or other places I’ve worked, such as Louisiana – you start to understand how small people really are on this earth.

I love the squelch of the mud under my feet and the rotten egg smell it gives off. I actually wear scuba booties as my field shoes whenever it is safe so that I can feel the ground beneath me. There is so much you can sense about the marsh that is hard to capture in discrete samples and computer modeling.

Is there anything you find surprising or enlightening about doing field work, in general?

KV: Another part of field work that has changed the way I think about science is talking to the people who live on these landscapes. I’ve worked on the Atlantic, Gulf and Pacific coasts of the U.S. and each of these landscapes differ, as do the local issues and personalities. And yet, these communities share a certain kinship.

They face similar challenges and rely on their relationships with the land – from Cajuns in Louisiana to oyster growers in Willapa, to Indigenous peoples in Bristol Bay. Because their lives are truly tied to the land, the local people teach me things about the place that I could not glean from studying scientific papers or samples. Being in the field where I can listen to the stewards of the land gives me a greater appreciation for the data we collect, a reason to pursue the science and a deeper understanding of the processes that have shaped it.

For more information, contact Kendall Valentine at kvalent@uw.edu

The blue whale is the largest animal on the planet. It consumes enormous quantities of tiny, shrimp-like animals known as krill to support a body of up to 100 feet (30 meters) long. Blue whales and other baleen whales, which filter seawater through their mouths to feed on small marine life, once teemed in Earth’s oceans. Then over the past century they were hunted almost to extinction for their energy-dense blubber.

As whales were decimated, some thought the krill would proliferate in predator-free waters. But that’s not what happened. Krill populations dropped, too, and neither population has yet recovered.

A recent theory proposes that whales weren’t just predators in the ocean environment. Nutrients that whales excreted may have provided a key fertilizer to these marine ecosystems.

Research led by 91̽�� oceanographers supports that theory. It finds that whale excrement contains significant amounts of iron, a vital element that is often scarce in ocean ecosystems, and nontoxic forms of copper, another essential nutrient that in some forms can harm life.

The open-access , the first to look at the forms of these trace metals in what’s commonly known as whale poop, was published in January in Communications Earth & Environment.

“We made novel measurements of whale feces to assess how important whales are to recycling important nutrients for phytoplankton,” said first author , a 91̽��doctoral student in oceanography. “Our analysis suggests that the decimation of baleen whale populations from historical whaling could have had larger biogeochemical implications for the Southern Ocean, an area crucially important to global carbon cycling.”

The Southern Ocean encircling Antarctica harbors little human life but is thought to play an important role in the global climate. Strong circumpolar currents bring deep ocean water up to the surface. Huge blooms of plant-like organisms known as phytoplankton support populations of krill, which are still harvested in unprotected waters today for aquaculture and pet food.

To investigate what role whale poop may have played in this ecosystem, the study analyzed five stool samples. Two samples were from humpback whales in the Southern Ocean and three were from blue whales off the central Californian coast. The samples were collected when researchers out studying whale populations saw an opportunity.

“The nice thing, I guess, is that whale excrement floats,” said senior author , an assistant professor of oceanography at the UW. Researchers collect it using a net attached to a jar to collect the substance typically found as a slushy or slurry material.

“The hypothesis is that the whales were actually adding nutrients to the ecosystem that these phytoplankton were able to use, so they would bloom more and then the krill could eat them,” Bundy said.

Previous research had found significant amounts of , like nitrogen and carbon, in whale poop samples. The new paper instead looked for metals that are in short supply far from land and are often a limiting factor for the growth of ocean ecosystems.

“In the Southern Ocean, iron is considered to be one of the most scarce, or limiting, nutrients that phytoplankton need to survive,” Bundy said

Results showed iron was present in all the samples. The researchers also found another metal, copper.

“We were really shocked by how much copper was in the whale poop. We initially thought, ‘oh, no, is the whale poop actually toxic?’” Bundy said.

Further analysis showed that organic molecules known as attached to the copper atoms transformed them into a form that is safe for marine life. Other ligands helped make the iron accessible to living organisms. The researchers don’t yet know the source of the ligands but suspect they may come from bacteria in the whales’ stomachs.

Bundy’s research focuses on trace metals in the ocean environment. This project began as Monreal’s introductory research project as a graduate student but it grew into a larger endeavor as the results came in.

“I think animals play a larger role in chemical cycles than many experts give them credit for, especially when thinking at the ecosystem scale,” Monreal said. “When I say animals, I really mean their gut microbiome. Based on what we see, it seems like bacteria in the whales’ guts could be important.”

Co-authors are postdoctoral researcher , former doctoral student and former undergraduate student from the UW; Matthew Savoca and Jeremy Goldbogen at Stanford University; Lydia Babcock-Adams at Florida State University; Logan Pallin, Ross Nichols and Ari Friedlaender at the University of California, Santa Cruz; John Calambokidis at the Cascadia Research Collective in Olympia, Washington; and at the National Oceanic and Atmospheric Administration and the UW’s Cooperative Institute for Climate, Ocean and Ecosystem Studies. Funders are MAC3 Impact Philanthropies, the MUIR Program at the Stanford Woods Institute for the Environment, the 91̽�� Program on Climate Change and the Ford Foundation.

For more information, contact Monreal at pmonreal@uw.edu and Bundy at rbundy@uw.edu. Note: Monreal is on New Zealand time through mid-February and responses may be delayed.

It turns out the rate of that increase matters for non-living systems, too. A recent 91̽�� study looked at how a major current in the Atlantic Ocean that includes the Gulf Stream will respond to a doubling of carbon dioxide from preindustrial levels. The , published in the Proceedings of the National Academy of Sciences, found that when carbon dioxide levels rise more gradually, they have less impact on the ocean circulation.

91̽��News sat down with author , a 91̽��postdoctoral researcher in the , to learn more about her study.

Why did you choose to study how the rate of rising CO2 affects the climate system?

Camille Hankel: In my PhD, some of my work was on “climate tipping points,” which emerge from the hypothesis that there might be some sort of critical thresholds of warming or CO2 change that can lead to very abrupt and irreversible change in some parts of the climate system. Through that work, I got exposed to some literature on “rate-induced tipping points,” which is the idea that instead of crossing a critical level, that there could be some critical rates of CO2 change that are important for the climate system.

Specifically, I read this study that was looking at this idea in the context of the AMOC, the , which is this large-scale ocean circulation. That study was using what we call a box model — a simplified, mathematical representation of the ocean circulation. And I thought, hey, I can run these global models, which are much more realistic representations of the Earth’s climate, including ocean, atmosphere, land and sea ice, and test whether the rate of CO2 change really is that important.

What is the Atlantic Meridional Overturning Circulation, which includes the Gulf Stream ocean current, and why is it so important for Earth’s climate?

CH: It’s one of the large-scale, key features of the climate system. In particular, it transports a lot of heat from the low latitudes in the South Atlantic to the higher latitudes closer to the North Pole. So it delivers a lot of heat, primarily to Northern Europe. It also distributes nutrients around through this sort of sinking motion that characterizes the circulation — it draws the surface waters down into the deep ocean, and recirculates deep water up to the surface. It’s a big feature of the climate system, particularly in the North Atlantic, but also globally.

We’ve heard about a potential slowdown of the Gulf Stream current that could affect European weather. This was dramatized (perhaps not accurately) in the 2004 disaster movie ‘.’ Are we actually seeing a slowdown in Atlantic Ocean circulation?

CH: We have a pretty short observational record of the AMOC current, and it’s sparse. You have to imagine, this is a 3D circulation in the entire Atlantic basin, and we have a couple little slices of data in particular parts of the Atlantic. We are seeing a modest slowdown so far, but it’s a pretty noisy and uncertain observational record, so it’s hard to tell.

I would say, however, that slowdown seen in current observations would match the model predictions of future slowdowns. And we also see a pattern in temperature changes where, while the rest of the globe is warming right now as we increase CO2, there’s what people call a “warming hole” over the North Atlantic: We’re not seeing as much warming in that North Atlantic region compared to the rest of the globe. And it’s hard to conclusively attribute what’s causing it in the Earth’s climate, but the idea is that the modest slowdown of the AMOC that we’ve seen so far could be one contributing factor to that lack of warming we’re seeing in the North Atlantic.

So the observations suggest some slowdown, though much less dramatic than what was depicted in that movie.

Why is the AMOC expected to slow down under climate change?

CH: One way of thinking about what drives this major ocean current is differences in ocean density. You have this really important zone in the North Atlantic where the waters sink because the surface waters are heavier than the waters below. When you change CO2 levels, you do two things. You start to warm the ocean’s surface, and by melting glaciers as well as changing sea ice, you add freshwater to the surface of the otherwise salty ocean. Both warming and freshening reduce the density of that upper ocean water and potentially inhibit or disrupt that critical sinking motion.

There are other ways of looking at it, but the one I look at in the study is understanding how those density perturbations happen in a higher-CO2 climate and how they modulate the sensitivity to the rate of CO2 change that I find in the AMOC’s response to CO2.

Your study finds that if atmospheric carbon dioxide doubles from pre-industrial levels more slowly, there’s less slowdown in the Atlantic Ocean compared to if CO2 doubles more quickly. Is that because everything is happening more slowly?

CH: Yes, that’s part of it. The different parts of the climate system — the ocean, atmosphere, and ice — all have different response timescales to CO2 changes, meaning they respond to perturbations with different lag times. Then how these components of the climate interact with each other under slower or faster CO2 changes can look very different, and in this case influence the ocean circulation.

Specifically, I found what’s known as a positive feedback — a sort of self-amplifying cycle — that helps explain why the level of AMOC weakening depends on the rate of CO2 change. In this feedback cycle, the initial modest amount of AMOC slowdown leads to a reduction of heat transport into the Arctic, which in turn cools the region and leads to a temporary period of Arctic sea ice expansion. This sea ice expansion causes more ice to be exported to the North Atlantic, where it melts and adds freshwater to the ocean, causing the AMOC to slow down even more: hence the self-amplifying cycle. It turns out that this feedback cycle is more effective at amplifying AMOC weakening under more rapid CO2 changes than under gradual CO2 changes.

What is the importance of this work?

CH: We know about AMOC slowdowns — there’s a ton of work on that, and the mechanisms that drive such an AMOC slowdown. But what’s new is this sensitivity of circulation changes to the rate of CO2 increase, independent of the total change in concentration of CO2.

When we think about policy and basic science, we tend to focus a lot on how the level of global warming can impact the climate system. I’m trying to bring a new perspective by thinking about the rate of increase as a driver itself, that could have a lot of impacts.

You can imagine that if multiple different climates are possible for the same level of warming, then limiting us to 1.5 C or 2 C could have different meanings, right? I do think the most important thing for the climate system is always how much CO2 have you put into the atmosphere, but how quickly you got to that point clearly matters as well.

��

For more information, contact Hankel at crhankel@uw.edu.

91̽�� oceanographer studies viruses – but not the viruses that get people worried. He studies viruses that infect ocean microorganisms, which are some of the most abundant living things on the planet.

Morris, a 91̽��associate professor of oceanography, previously found that the most common bacteria in the oceans, SAR11, hosts a virus in its DNA. That virus is dormant most of the time, but when and how it erupts could play important roles in ocean ecology and evolution.

Now Morris and a collaborator at the University of California, Los Angeles, are going out with students to collect more of these tiny bacterial hosts and their viral guests to understand how these relationships change depending on the place or the season. They leave Dec. 16 aboard 91̽��School of Oceanography’s small research vessel, the .

91̽��News asked Morris a few questions about the upcoming cruise, which includes four undergraduate students, as part of an occasional series, “In the Field,” highlighting 91̽��field efforts.

Where are you going, and when?��

Robert Morris: Our research cruise will travel from the to the San Juan Islands. This track gives us access to important areas in Puget Sound as well as to the Strait of Juan de Fuca, where open ocean water enters the Puget Sound.

We leave on Monday, Dec. 16 and return Friday, Dec. 20.

Have you visited these waters in the past?

RM: This is our third cruise. The first cruise was in September 2023 and focused on the Puget Sound main basin and Hood Canal. The second cruise was this past July and focused on the main basin, the Strait of Juan de Fuca, and areas around the San Juan Islands. This third cruise will be a repeat of the summer cruise, but at a different time of year to investigate seasonal differences in the viruses that infect marine bacteria.

Who is going on the cruise?

RM: I am chief scientist on all three cruises, and , at the University of California, Los Angeles, is co-chief scientist. Each cruise has one additional mentor and four UCLA undergraduates.

For this cruise, the mentor is Jason Graff at Oregon State (past mentors have been 91̽��graduate students Kunmanee Bubphamanee and Dylan Vecchione). For this cruise, the undergraduate students are Grace Donohue, Natalie Falta, Eleanor Gorham and Madeleine Swope.

What does your team hope to learn from this place?

RM: On the scientific side, we hope to identify spatial and temporal patterns in viruses that infect the oceans’ most abundant bacteria, which is SAR11. More specifically, we collect samples to identify the number and types of SAR11 bacterial cells that have viruses in their genomes and isolate new SAR11 species and the viruses that infect them throughout Puget Sound in summer and winter. We’re also curious how the number of viruses affects infection patterns across our sample sites and seasons.

From an outreach perspective, the field program was designed to allow students from 91̽��and UCLA to collaborate and learn “hands-on” oceanography and to see how research ideas and experiments inform each other, especially when working in interdisciplinary teams and with active mentorship. We expect this field experience to expose more students to oceanographic fieldwork, which may inspire further studies in oceanography or other sciences.

If this is a repeat effort, will this year be different in any way?

RM: The upcoming cruise is the first one that will be conducted in the winter, with the goal of identifying viruses with different infection strategies. For instance, in the winter we expect to find fewer SAR11 cells, but more with viruses hiding out in their genomes.

Briefly, what’s a typical day in the field (if there’s such thing as a typical day)? And what’s something you enjoy about doing this field work?

RM: We start the day by collecting samples and setting up an incubation study, where we incubate and grow more bacterial cells. We do four incubation studies on each cruise. The study is designed to multiply bacterial viruses in a way that increases the number of cells that are infected. After the incubation experiment is set up, we visit other sites to collect background data that tells us about the environmental conditions in the surrounding area.

One of the most exciting parts of the day-to-day activities is that you don’t know what the day will bring. Much of the work is outside, so it can be sunny and calm, or rainy and rough. The work gets done either way!

Anything you’d like to add?

RM: We are working on a collaborative manuscript that will include data from the incubation studies and all student participants. 91̽��graduate student , a doctoral student in Earth and space sciences, conducted research in my laboratory for her 91̽��Astrobiology research rotation, and was able to gain field research experience during the second cruise. Two 91̽��graduate students in my lab, and , will include bacterial culture and genetic sequencing data in future manuscripts.

Lastly, this has been an amazing experience and although many of the students from UCLA have not stayed in oceanography, most have applied to or have gone on to graduate school in science. It has been fantastic interacting with all of the students and seeing them grow into experienced oceanographers over the length of the cruises.

For more information, contact Morris at morrisrm@uw.edu.

Six 91̽�� subjects ranked in the top 10, and atmospheric sciences maintained its position as No. 1 in the world on the����list for 2023. The ranking, released at the end of October, was conducted by researchers at the ShanghaiRanking Consultancy, a fully independent organization dedicated to research on higher education intelligence and consultation.

Other 91̽��subjects in the top 10 include oceanography at No. 2; public health at No. 5; biological sciences and statistics at No. 7; and clinical medicine at No. 9.

“The 91̽�� is a powerhouse for research and discovery — both within and across disciplines,” said 91̽��President Ana Mari Cauce. “That research leads to cures, advances innovation in areas like climate science and transforms our understanding in ways that are critical to the future for all people and communities. We are grateful to see the impact of this vital work recognized by this esteemed organization.”

This ranking takes into account more than 5,000 universities around the world in 54 subjects across natural sciences, engineering, life sciences, medical sciences and social sciences. More information about the methodology used to calculate the rankings can be found .

In 2023, the 91̽��was ranked No. 18 on the group’s annual��Academic Ranking of World Universities��list.

Note: The subject names below are general descriptions from the ranking website, and not necessarily the names of the 91̽��unit ranked.

To paraphrase Mark Twain, reports of declining phytoplankton in the North Atlantic may have been greatly exaggerated. A prominent 2019 study used ice cores in Antarctica to suggest that during the industrial era, with worrying implications that the trend might continue.

But new research led by the 91̽�� shows that marine phytoplankton — on which larger organisms throughout the marine ecosystem depend — may be more stable than believed in the North Atlantic. The team’s analysis of an ice core going back 800 years shows that a more complex atmospheric process may explain the recent trends.

The was published the week of Nov. 13 in the Proceedings of the National Academy of Sciences.

Tiny floating photosynthetic organisms known as phytoplankton form the base of the marine ecosystem. These microscopic creatures are also important to the planet as a whole, producing roughly half the oxygen in Earth’s atmosphere.

Since phytoplankton are hard to count, scientists attempt to measure their abundance in other ways. Phytoplankton emit dimethyl sulfide, an odorous gas that gives beaches their distinctive smell. Once airborne, the dimethyl sulfide converts to methanesulfonic acid, or MSA, and sulfate. These eventually fall out onto land or snow, making ice cores one way to measure past population sizes.

“Greenland ice cores show a decline in MSA concentrations over the industrial era, which was concluded to be a sign of declining primary productivity in the North Atlantic,” said lead author , a 91̽��doctoral student in atmospheric sciences. “But our study of sulfate in a Greenland ice core shows that MSA alone can’t tell us the whole story when it comes to primary productivity.”

Since the mid-1800s, factories and tailpipes have also been spewing sulfur-containing gases into the air. Those gases have slightly different forms of sulfur atoms that make it possible to distinguish the marine and land-based sources in ice cores.

The new study goes further back than the previous study by measuring several sulfur-containing molecules in an ice core from central Greenland with layers spanning the years 1200 to 2006. The authors show that human-generated pollutants changed the atmosphere’s chemistry. This, in turn, altered the fate of the gases emitted by phytoplankton.

“When looking at the ice cores, we found that sulfate derived from phytoplankton increased during the industrial era,” Jongebloed said. “In other words, the decline in MSA is ‘offset’ by the simultaneous increase in phytoplankton-derived sulfate, indicating that phytoplankton-derived sulfur emissions have remained stable overall.”

When that balance is included in the calculations, the phytoplankton populations seem fairly stable since the mid-1800s. The researchers caution, however, that marine ecosystems remain under threat from many directions.

“Measuring both MSA and phytoplankton-derived sulfate gives us a fuller picture of how the emissions from marine primary producers have changed — or not changed — over time,” said senior author , a 91̽��professor of atmospheric sciences.

“Ice core measurements along with other independent estimates of phytoplankton abundance (such as chlorophyll measurements) and paired with modeling studies (which help us estimate how atmospheric chemistry and climate change over time) can help us understand how marine productivity has changed in the past and how productivity might change in the future.”

Other co-authors are research scientist , doctoral student and former undergraduates and at the UW; Jihong Cole-Dai and Carleigh Larrick at South Dakota State University; William Porter and Linia Tashmim at the University of California, Riverside; and Lei Geng at the University of Science and Technology of China.

The study was funded by the National Science Foundation and the National Natural Science Foundation of China.

For more information, contact Jongebloed at ujongebl@uw.edu or Alexander at beckya@uw.edu.

Ocean temperatures and their connections to weather trends have been making news. Five 91̽�� experts offer their perspectives on the current El Niño — a climate pattern in the tropical Pacific Ocean that affects weather worldwide. 91̽��researchers comment on the current El Niño, its effect on weather in the Pacific Northwest, as well as on regional and global ocean temperature trends.

, a 91̽��research scientist at the , comments on the developing El Niño:

“This El Niño has evolved in a really interesting way. Since spring, the dynamical models have very confidently predicted an El Niño event. But while the key region of the tropical Pacific has warmed quickly, the typical atmospheric response has lagged. The atmosphere in the tropical Pacific is only now becoming more typical of an El Niño event, although it is still not fully matching the ocean surface. That’s unusual, because the tropical ocean and atmosphere tend to evolve together.

“It will be interesting to see how this El Niño continues to evolve over the next few months, which will help determine the extent of impacts on our upcoming winter weather. Remote impacts in places like Seattle tend to be stronger for stronger El Niño events. While sea surface temperature has typically been the main measure, the impacts might very well depend more on the atmospheric response. So the evolution of the system over the next few months will be key to the eventual local impacts in places like Seattle.”

Dennis Hartmann, professor of atmospheric sciences at the UW, on El Niño and its effects:

“The impact of El Niño on the Pacific Northwest varies a lot from one event to the other, depending on the spatial structure and size of the sea surface temperature changes in the tropics, and on the state of the atmosphere between the tropics and the Pacific Northwest. For that reason, the predictions of Pacific Northwest impacts based upon El Niño events that happened in the past are quite uncertain.

“In addition, the climate has warmed significantly in both the tropics and outside the tropics since some of the prior big El Niño events, in the 1970s and 1980s. That may add an additional complication to making an accurate forecast of how this winter will be different because of the current El Niño event.”

Nick Bond, a research scientist at CICOES and Washington’s state climatologist, on El Niño and its effects on Washington’s weather:

“El Niño conditions are present now in the tropical Pacific Ocean, and they are very likely to persist through the coming winter. The effects on Washington’s weather are expected to feature relatively warm, and perhaps drier, weather than usual after Jan. 1, and ultimately a lower-than-normal snowpack in our mountains at the end of winter. El Niño’s impacts on the weather in Washington state tend to be more consistent in the middle to latter part of the winter.

“But this is not written in stone — there has been variability among past El Niños in terms of effects on Washington’s winter weather.”

Jan Newton, senior principal oceanographer at the 91̽��Applied Physics Laboratory and director of the UW-based , on what oceanographers are seeing in regional waters:

“Conditions off Washington’s outer coast have varied and are mainly influenced by changes in coastal upwelling and downwelling in the Pacific Ocean. Temperatures off the outer coast are now 4 degrees Fahrenheit (about 2 degrees Celsius) above normal, though variable.

“In Puget Sound, we’re starting to see surface water temperatures shift from cooler than normal, or normal, to consistently warmer than normal, but only by less than one degree Fahrenheit (half a degree Celsius). Given the large-scale warmth in the satellite-measured sea surface temperatures offshore, I do expect that we will continue to see warmer-than-normal sea temperatures in Puget Sound.�� However, it’s hard to predict if these differences from the average will stay small or will increase. What happens next will depend on ocean conditions and local weather.”

LuAnne Thompson, 91̽��professor of oceanography, on the :

“The recent acceleration of ocean warming in the Atlantic is unprecedented in the historical record, and has created an Atlantic-wide marine heat wave. The ability of the ocean to absorb and store vast amounts of heat makes these types of events last longer. I study marine heat waves with a focus on their evolution in time and space. However, with more long-lasting, basin-wide events, such as the one we are seeing now in the Atlantic Ocean, we will need to reevaluate our approach.

“At a particular location, a marine heat wave occurs when the sea surface temperature is above a threshold, defined by what is typical for that time of year, and lasts for at least five days. However, with the global warming projected over coming decades, these dangerous hot water events will no longer be localized and of finite duration — they will no longer fit the traditional definition of marine heat waves. Instead, these marine heat wave events will become more persistent and widespread, and eventually will cover entire ocean basins.”

For more information, contact Levine at aflevine@uw.edu, Hartmann at dhartm@uw.edu, Bond at nab3met@uw.edu, Newton at janewton@uw.edu and Thompson at luanne@uw.edu.

The U.S. National Science Foundation Sept. 21 that it is awarding a coalition of academic and oceanographic research organizations a new five-year cooperative agreement to operate and maintain the . The 91̽��, Oregon State University and project lead Woods Hole Oceanographic Institution will continue operating the OOI, a science-driven ocean observing network that delivers real-time data from more than 900 instruments to address critical science questions regarding the world’s oceans. The coalition was previously funded in 2018.

Under this new $220 million total investment, each of the three institutions will continue to operate and maintain the portion of the observatory for which it is currently responsible. The award amount for the 91̽��is $52.4 million.

“I am extremely excited about this next five years of operations and the continued opportunities that the Regional Cabled Array will provide for unparalleled environmental data throughout entire ocean depths in some of the most dynamic environments on Earth,” said , a 91̽��professor of oceanography and director of the Regional Cabled Array. “Decade-long measurements from more than 150 instruments sampling every second make this a perfect system to captivate users with ‘new eyes’ and AI applications, which will undoubtedly lead to important new discoveries and predictive capabilities.”

91̽��operates what’s now known as the , an underwater observatory ��on the seafloor of the Juan de Fuca tectonic plate — a small tectonic plate off Newport, Oregon, that’s home to an active underwater volcano and deep-ocean life — at 1 to almost 2 miles depth. The array also has instruments that move up and down to monitor properties in the ocean above. More than 500 miles (900 kilometers) of submarine fiber-optic cable provide power, real-time data transmission and live, two-way communication between the observatory and computers back on shore.

The Regional Cabled Array is the largest component of the full OOI network that collects and shares measurements from more than 900 instruments on the seafloor and on moored and free-swimming robotic platforms. The instruments are maintained with regular, ship-based expeditions to the equipment sites. All data are freely available to users worldwide, including members of the scientific community, policy experts, decision-makers, educators and the public.

“We’re so pleased to have the opportunity to continue providing streaming, real-time ocean data for all to use as part of the OOI,” said , the Maggie Walker Dean of the 91̽��College of the Environment. “This support will allow the global research community to conduct multi-faceted, cutting-edge science for years to come, which is vital to understanding and protecting our oceans.”

Oregon State University will continue to operate the Endurance Array in the coastal waters near Oregon. Woods Hole Oceanographic Institution, which is based in Massachusetts, will operate projects outside the Pacific Northwest region, inluding the Pioneer Array off the North Carolina coast, subject to environmental permitting, and two global arrays, off the southern tip of Greenland and at a long-term ocean observing station in the Gulf of Alaska.

“OOI has proven to be an exceedingly valuable source of information about the ocean. Its freely available data are contributing to better understanding of ocean processes and how the ocean is changing,” said NSF Program Officer for OOI George Voulgaris.�� “Scientists are using OOI data as the source of cutting-edge scientific discoveries — everything from getting close to predicting underwater volcanic eruptions to changing ocean circulation patterns that have real life implications for weather and fishing patterns.

“OOI data also are serving as inspiration for students in the classroom, who are excited about learning about the ocean with access to real-time ocean data. We at NSF are proud of our continued investment in making these data available.”

Woods Hole Oceanographic Institution will continue to lead operations and management of OOI through 2028, and OSU will continue to house and operate the data center that ingests and delivers all OOI data.

For more information about the Regional Cabled Array, contact Kelley at dskelley@uw.edu.

Adapted from a from Woods Hole Oceanographic Institution.

In the frigid waters surrounding Antarctica, an unusual seasonal cycle occurs. During winter, from March to October, the sun barely rises. As seawater freezes it rejects salts, creating pockets of extra-salty brine where microbes live in winter. In summer, the sea ice melts under constant daylight, producing warmer, fresher water at the surface.

This remote ecosystem is home to much of the Southern Ocean’s photosynthetic life. A new 91̽�� study provides the first measurements of how sea-ice algae and other single-celled life adjust to these seasonal rhythms, offering clues to what might happen as this environment shifts under climate change.

The , published Sept. 15 in the International Society for Microbial Ecology’s ISME Journal, contains some of the first measurements of how sea-ice microbes respond to changing conditions.

“We know very little about how sea-ice microbes respond to changes in salinity and temperature,” said lead author , a 91̽��postdoctoral researcher who did the work while pursuing her doctorate in oceanography at the UW. “And until now we knew almost nothing about the molecules they produce and use in chemical reactions to stay alive, which are important for supporting higher organisms in the ecosystem as well as for climate impacts, like carbon storage and cloud formation.”

The polar oceans play an important role in global ocean currents and in supporting marine ecosystems. Microbes form the base of the food web, supporting larger life forms.

“Polar oceans make up a significant portion of the world’s oceans, and these are very productive waters,” said senior author , a 91̽��assistant professor of oceanography. “These waters support big swarms of krill, the whales that come to feed on those krill, and either polar bears or penguins. And the start of that whole ecosystem are these single-celled microscopic algae. We just know so little about them.”

The tiny organisms are also important for the climate, since they quietly perform photosynthesis and soak up carbon from the atmosphere. Polar algae are especially good at producing sulfur-containing molecules that give beaches their distinctive smell and, when lofted into the air in sea spray, promote formation of clouds that can reduce penetration of solar rays.

Antarctic sea ice, though long stable, is at an this year.

In other oceans, satellite instruments can capture dramatic seasonal phytoplankton blooms from space — but that isn’t possible for microbes hidden under sea ice. And Antarctic waters are particularly challenging to visit, leaving researchers with almost no measurements in winter.

In late 2018, Dawson and co-author traveled to , a U.S. research station on the West Antarctic Peninsula. They used a small boat to sample seawater and sea ice at the same nearby sites every three days.

Back on shore, the two graduate students performed 10-day experiments in tanks to see which microbes grew as temperature and salinity were adjusted to mimic sea-ice formation and melt. They also shipped samples back to Seattle for more complex measurements of the samples’ genetics and metabolites, the small organic molecules produced by the cell.

Results revealed how single-celled algae deal with their fluctuating environments. As temperatures drop, the cells produce cryoprotectants, similar to antifreeze, to prevent their cellular fluid from crystallizing. Many of the most common cryoprotectant molecules were the same across different microbial lifeforms.

As salinity changes, to avoid either bursting in freshening waters or becoming desiccated like raisins in salty conditions, the cells change the concentration of salt-like organic molecules. Many such molecules serve a dual role as cryoprotectants, to balance conditions inside and outside the cell to maintain water balance.

The results show that under short-term temperature and salinity changes, community structure in each sample remained stable while adjusting the production of protective molecules. Different microbe species showed consistent responses to changing conditions. This should simplify modeling future responses to climate change, Young said.

Results also hint that the production of omega-3 fatty acids may decline in lower-salinity environments. This would be bad news for consumers of krill oil supplements, and for the marine ecosystem that relies on those algae-derived nutrients. Future research now underway by the 91̽��group aims to confirm that result — especially with the prospect of increasing freshwater input from melting sea ice and glaciers.

“We’re interested in how these sea-ice algae contend with changes in temperature, salinity and light under normal conditions,” Dawson said. “But then we also have climate change, which is completely remodeling the landscape in terms of when sea ice is forming, how much sea ice forms, how long it stays before it melts, as well as the quantity of freshwater input from glaciers. So we’re both trying to capture what’s happening now, and also asking how that can inform what might happen in the future.”

The study was funded by the National Science Foundation, the Simons Foundation, and the Alfred P. Sloan Foundation. Other co-authors are Anitra Ingalls, Jody Deming, Joshua Sacks and Laura Carlson at the UW; Natalia Erazo, Elizabeth Connors and Jeff Bowman at Scripps Institution of Oceanography; and Veronica Mierzejewski at Arizona State University.

For more information, contact Dawson at hmdawson@uw.edu or Young at youngjn@uw.edu.