Inspiring students to pursue science, fight climate change and impact the community

Inspiring students to pursue science, fight climate change and impact the community

By Brittany Edelmann and Carly Menker, Photos by Carly Menker, May 1, 2022 –

Janyiah, a ninth-grade student at Gary Comer College Prep, started “falling in love with science” three years ago in the South Side school’s proactive STEM curriculum. She enjoyed the mix of her two favorite subjects: math and reading. Janyiah, in the Comer middle school at the time, is now a freshman at Comer Prep in Jessica Stevens’ environmental science class. Janyiah said she and her classmates transmitted electricity to a light bulb, and “it was so cool.”

Skylan, also a ninth grader at Gary Comer College Prep, is finding her passion through Steven’s class as well. “I want to be a wildlife conservationist,” Skylen said. She said she noticed how Stevens is an environmental scientist and seeing what she does and how she goes out into the field really helped her decide what she wants to do.

At the age of 14, Sanaa was a Green Teen at the Gary Comer Youth Center when she was “working as a small little agricultural farmer,” and started learning about growing food and environmental science. Then she graduated and became a part of the Comer Crops Program. She loves seeing the growth, seeing food that she planted and seeing Maine in the summer to give more students the chance to experience this type of work and provide further inspiration and confidence to pursue a career in science.

Scientists come to speak with current students often. Stevens said students tell her how much they love talking to a “real scientist,” which shows them the researchers aren’t as “boring” as they originally thought.

Students in the middle and prep school and members of the youth center, all on the Comer Education Campus at 7200 S. Ingleside Ave., where the focus is on impacting their communities and beyond through hands-on, interactive learning related to science.

The underlying hope of founder  Gary Comer had in regard to the program was about “how young people could learn here and then go out in the world and make a difference,” Marji Hess, previous urban agricultural director  at GCCP, said at the 2021 annual Comer Climate Conference. The conference brings together top scientists from around the world to discuss their research that documents climate change and urgent solutions. Hess now leads a new Comer Family Foundation initiative empowering youth to address the climate crisis.

Students at the prep school (GCCP) have had opportunities to travel to Mongolia on field trips with scientists, experiential learning they took back into the classroom to inspire other students. Hess also said GCCP students have  traveled with her to Yellowstone National Park for a week and “every single one of them said it changed their lives in a way that they never expected.”

Patricia Joyner was one of those students. She went to Yellowstone three years in a row and  she’s now an undergraduate studying with Aaron Putnam, an assistant professor of Earth sciences with the University of Maine’s Climate Change Institute and a scientist affiliated with Comer climate research initiative. Another initiative they hope to implement is to take current GCCP students to Maine in the summer to give more students the chance to experience this type of work and provide further inspiration and confidence to pursue a career in science.

Stevens implements “culturally relevant and hands-on,” learning with the goal that her students “become scientifically literate adults and hopefully climate leaders.” Stevens is also working on piloting a student-centered climate change unit for the first time this year, which will include things like the topic of heat islands but specific to Chicago.

She received a grant to purchase handheld air quality sensors so her students can do a long-term investigation into air quality around the school. They hope to compare different areas around the school and how air quality affects human health. “Most of our students are in those zones and are in the communities that experienced the worst of environmental effects due to redlining,” so this experiment is especially impactful, Stevens said.

A day in the life of her classroom offers experiences her students say they cherish and enjoy.

On a typical day, Stevens teaches science at Gary Comer College Prep in Classroom 109. Decorated with posters promoting safety and respect, she works hard to instill lessons like these while teaching her students to be passionate about science. Science did take a bit of a temporary back-burner role after the school returned to in-person class from remote learning during the pandemic. There was “a lot of social emotional learning,” said Stevens. It’s “important that they know how to be a social human being again in a classroom.”


Stevens’ class is working on building a model power grid as part of their Resources and Consumption unit. Her teaching approach involves a lot of hands-on learning as well as demonstrations. To start, she asks students, “How are you feeling today?” She asks for a thumbs up for a color such as yellow or green, which can indicate emotions such as pleasant or blessed. She then engages students by asking them critical questions they answer to build familiarity with the topic. She makes it clear to students that “science isn’t about being right, it’s about figuring things out.”


Stevens emphasized the fundamentals of scientific learning focuses on the scientific method. It’s a process of acquiring knowledge that incorporates careful observation, skepticism  and assumptions based on interpretation of observations along with documentation of methods and data that can be repeated by others.  When it comes to science, student Elicia said she loves how “you can learn new things about the whole world and earth and nature.”


As class continues, Stevens explains the importance of different types of energy, asking students questions about it as she goes along. She elaborates on how friction is a type of kinetic energy that converts into thermal energy. With 24 kids in a class, keeping everyone focused is a priority for Stevens along with students them remaining clear on the content. “It’s really important to me that my students understand the ‘why’ behind what we’re learning,” she said.


Students are intensely focused in Stevens’ class as eager participation shows. Their engagement with the content reflects results in the caliber of their hard work as well as in their growth and love for science. When she asks a question, multiple hands raise to answer. She says she’s not the student’s favorite the first half of the year – the class is tough. But by the second half of the year, the students come around and they get used to her teaching and grow to love it. Steven says while she has “very high expectations,” she knows just how capable they are.


When working on a unit in class, the lesson plans are designed to go through the topic in a way that is accessible and tangible to students. Typically, they encompass a basic scientific question, covering all aspects of it as Stevens leads the class through it. “We like to have a lot more hands- on, involved story lines,” she said. “Meaning that [students] actually investigate the entire problem, from start to finish.”
One example of Stevens’ hands-on learning is finding the answer to the question: “How does steam generate electricity?” Stevens took her class through a demonstration of this and visually showed them in a session how this occurs. Another example of a lab of hers included the history of the electricity lab, which was equally as interactive. Jordyn, one of Steven’s students, said what he likes about science is seeing the experiments and “the cool stuff.”


There are no textbooks in Stevens’ classes. Instead, she’s adopted a more student-involved method: the Interactive Science Notebook that each student makes. “Environmental science is always changing,” she said. The textbooks wouldn’t be able to give the same enrichment and learning that Stevens’ handout and lesson packets can. Stevens also says cutting out pages and contributing other resources, creating the notebook, can give their mind’s a break and be calming and therapeutic for students too.


This year, Stevens and Hess worked together with Alice Doughty, a professor at the University of Maine, to create a climate change unit based on the Next Generation Science Standards and Problem Based Learning. Not only did they want to bolster the breadth of their science program, but they also wanted to focus on “building a better curriculum using the next generation’s standards, which are the federal standards that all students would be using throughout the country.” In doing so, this would improve the futures of all the Gary Comer Prep students. “We’re switching to that to give our students more equitable opportunities and background and support before they go off to higher education,” Stevens said.


To make their Interactive Science Notebooks, there is a lot of cutting, pasting and handouts involved. These notebooks serve as a reference for students throughout their learning process where Stevens focuses on skill-based grading, “to watch how students’ progress and see if they’re going to be supported in their next level of classes.”


This class demonstration showed a direct application of changing potential energy to kinetic and thermal energy to steam and sound energy. Before starting, water waits to boil on a hot plate as the first step. Stevens asked students, “What will happen? What type of energy?” “Nuclear?” one student asked. “Maybe see steam?” students replied. Even when students become frustrated at times with science terminology, Stevens reminds them, “Terminology is hard. That’s a part of science.”


To make sure that every student feels engaged in the lesson and can see, Stevens walks around with parts of the demonstration bringing it around to them. Stevens and Hess focus on supporting their students in any way they can, especially through their scientific learning. “We’re trying to help our young people build resiliency and leadership skills,” Hess said.


Students take vigorous notes as Stevens continues to explain the background to her energy demonstration. A crucial part of the learning is the student engagement that Stevens facilitates by sparking discussion about the topic that the class is focusing on while sprinkling in content questions to get students thinking. “I love the discussions we have in this classroom,” student Kimiyrah said.


By lighting a flame inside a mini steam engine, Stevens can generate enough heat to make the wheel turn on the engine. When she opens the top, a whistling sound is made, reflecting the energy that is converted to sound. Each student watches Stevens with a razor-sharp focus. “They bring so much background knowledge to my class and I love finding ways to incorporate their existing knowledge and experiences into Environmental Science,” she said.


All eyes are on the demonstration as students investigate the outcome of the energy changes in the experiment. One way Stevens gets her students so engaged is by bringing the meaning of the lesson to experiences that matter in their lives. “Right now, we’re learning about how we generate electricity and transfer it to power our homes,” she said. “I framed this as ‘How do you charge your phone?’ They were really into the lessons after that.”


Emphasizing the values Stevens instills in her students, they help clean up out of respect on their way out of the classroom. Instead of rushing out, many linger to chat with Stevens, a connection to the quality of teaching she gives to her students. “This is my favorite class,” said Janyiah (not shown here). “She’s my favorite teacher,” she added. “I knew there was a reason I woke up this morning,” Stevens said.

(Note: For reasons of privacy and safety, students are identified by first name only.)

Glacier geologists search for global climate clues to support urgent action now

Glacier geologists search for global climate clues to support urgent action now

By Poonam Narotam, Dec. 15, 2021 –
When he’s not teaching earth science classes and analyzing data at the University of Maine, glacier whisperer Aaron Putnam is trekking into the high Himalayas or New Zealand’s Southern Alps to study where glaciers once stood.

The United Nations officials behind the recent global COP26 climate conference urged countries to eliminate carbon emissions by 45% below 2010 levels by 2030 to stabilize global warming driven by fossil fuel use. No definitive commitments were made toward that goal.

Researchers deepen our knowledge of climate systems and models in the hopes of awakening the urgent need for international solutions before global warming hits a tipping point. Putnam asks the big questions vital to modeling future climate patterns: What caused the last global ice age and how did it suddenly end?

“We need this information from the past to help calibrate our understanding of what’s coming in the future,” said Putnam, 40, an associate professor of earth science at the University of Maine.

Putnam is one of many paleoclimate scientists who studied under and worked with George Denton, distinguished professor at the University of Maine’s School of Earth and Climate Sciences and Climate Change Institute. Putnam and Denton spent the better part of a decade developing a new hypothesis published in March introducing how the westerly winds, the earth’s strongest wind system, contribute to climate shifts between glacial (when glaciers grow) and interglacial periods (when glaciers decline). Both scientists discussed their research at the Comer Climate Conference this fall, an annual gathering of international researchers held remotely this year due to the pandemic.

The findings prompted Putnam to look closely at the similarities between modern global warming and the end of the last ice age, the primary difference being that the pace of today’s climate change is escalating due to human-induced carbon emissions. Putnam, along with Denton and other paleoclimate scientists in their group, tested the hypothesis by mapping key glacier sites in both hemispheres. They found this dynamic system could have a dramatic impact on melting ice in the Southern Hemisphere and global sea level rise.

Putnam studies the land and patterns of rocks to identify where glaciers used to be. He draws detailed maps of the ridges and valleys, and collects rock samples. His research teams ship hundreds of pounds of rock to the Maine lab for testing to determine when the ice sheet melted and exposed the rock.


Aaron Putnam's Field Notes
Aaron Putnam takes copious notes in his all-weather geological field book and illustrated a boulder he sampled in New Zealand in 2014. “I don’t know how he gets all that detail in there,” said Lauren Woods, 22. “His ability to draw things is astonishing.” Woods first took Putnam’s Habitable Planet Seminar as a college sophomore and studies glacial geology and geochronology as a master’s student with Putnam at the University of Maine. (Photo Credit: Aaron Putnam/UNIVERSITY OF MAINE)


Using chemical analysis techniques, graduate students measure the amount of the isotope Beryllium-10 in the rock. The isotope forms in exposed rock when cosmic rays collide with quartz. Piecing together hundreds of precise calculations, Putnam’s team develops a chronology of how that glacier grew and shrank.

As the pandemic prevented travel to Southern Hemisphere glacier sites, Putnam led fieldwork in Wyoming in July to study the Laurentide Ice Sheet, the largest ice sheet of the last ice age. The ice sheet covered the upper half of North America during the ice age and its retreat gouged out the Great Lakes we know today, filling them with meltwater. Expanding glacier chronologies in both hemispheres furthers our understanding of global climate systems and the new patterns Putnam and Denton have been studying.

“We were looking at the surface [of a boulder] to see if it would be good to sample,” said Lauren Woods, a master’s student on the Wyoming trip. “He just kind of leans down to the rock and whispers, ‘Tell us your secrets.’”

Reaching remote field sites

Glacier research also requires finding the right combination of flights, boating routes, drives and treks into some of the world’s most remote places. Putnam said it took his team a week to traverse the Lunana Snowman trek on the border of Bhutan and Tibet, a snowy route amongst glaciers along the main spine of the Himalayas

Disconnected from mainstream communications and living among communities that don’t speak English, Putnam’s group relies heavily on local guides to coordinate directions, emergencies, and food.

Putnam’s Ph.D. student Peter Strand said they bought a sheep from a local herder in Mongolia to keep everyone fed.

“It’s not a good place in the world to be a vegetarian,” said Strand, who jumped at the opportunity to sign on as Putnam’s first Ph.D. student.

“He’s always encouraging everyone to think big,” Strand said. He said Putnam prompts them with the question: “What can this really tell us about how the whole earth system works?”

Without much cell phone coverage, Putnam said he feels more present and able to think in the “glacial graveyards,” areas of land marked by bodies of water and ridges of rock, called moraines, lining the landscape where glaciers once discarded them.

The ‘science’ gene

“When you’re young, you think you’re invincible,” said Putnam. Now the father of a 3-year-old, he’s aware of the dangers of exploring remote terrains. “You had to go over a number of very high passes to get to where you’re going,” he said of his many adventures. “It’s not like you just go back downhill.”

When there was Wi-Fi in the Himalayas, Whatsapp was his lifeline to his wife and baby. Nowadays, he looks forward to spending fewer than four months a year in the field in favor of his dad duties.

Putnam’s love of science runs in the family. His father, archaeologist David Putnam, took a college class with George Denton, who later became Putnam’s Ph.D. adviser. Putnam’s wife is a paleoceanographer and led research on a cruise off the Gulf of Maine in August.

“We’re trying to see if we can begin to plan our fieldwork in ways that we can do it together,” Putnam said. The climate science couple is considering Southern California for her research and New Zealand for his.

They haven’t been in the field together since Putnam’s wife visited him in New Zealand several years ago and he proposed on a peak of the Tasman Glacier.

“I was kind of a nervous wreck about the whole thing, like what if she says no?” Putnam said. She said yes, and they helicoptered back down to finish the day’s work.

Growing up in the Arctic Circle

When Putnam was in high school, his family spent a year in Utqiagvik (then called Barrow) in the northern tip of Alaska.

“We could see when the sea ice [or frozen ocean water] would come in and when it would leave,” Putnam said. The deep north first exposed him to how climate impacted people. The Inupiat people native to Alaska travel over sea ice to hunt and fish for food during the winter.

He celebrated his eighteenth birthday with his biology teacher in the Arctic Ocean on an icebreaker, a ship designed to cut through the ice sheets on the water. His mom snuck a birthday cake for him onto a helicopter during a supply run from the mainland.

“She had me thoroughly embarrassed,” Putnam said. “But that [trip] really clinched it for me; I knew somehow I wanted to get involved, I wanted to be a part of the climate science community.”

“There’s just some sort of intrinsic curiosity in trying to figure out how things work,” he said. “That’s what I find fun about it.”

Determined to continue developing glacier chronologies to advance climate research, Putnam is laying plans for next year’s field seasons – hopefully to Patagonia. His and others’ glacier chronologies demonstrate the complexity of dynamic global climate cycles documented across much of the past 1 million years. And yet, scientists agree that human-driven ice melt and climate change is eclipsing the speed at which climates changed in the past.

Photo at top: Glacier geologist and paleoclimate scientist Aaron Putnam, 40, snaps a photo of a boulder in Soda Lake, Wyoming, in July 2021. The Laurentide Ice Sheet covered the northern regions of the continent, including Wyoming, during the last ice age. The retreat of the ice sheet gouged out the Great Lakes we know today and filled them with meltwater. (Lauren Woods/UNIVERITY OF MAINE)

Poonam Narotam is a health, science, and environment reporter at Medill. You can follow her on Twitter at @namsorama.

Climate change threatens El Niño crop and rainfall boosts with severe disruptions

Climate change threatens El Niño crop and rainfall boosts with severe disruptions

By Carly Menker, Dec. 14, 2021 –

Columbia University Ph.D. student Celeste Pallone devotes her research time observing Eastern Equatorial Pacific dwelling planktonic foraminifera – very tiny creatures that can give huge clues into the pace of ocean climate change.

“Marine sediment cores act as an archive of sea surface temperatures, past environments, including past temperatures, and general environmental factors, such as past global ice volume,” she said of the single-celled, shelled organisms she studies at Columbia’s Lamont-Doherty Earth Observatory high in the Palisades outside New York City. “I examine these proxies, which can be biological or chemical or physical, and then using them I reconstruct oceanographic conditions in the past helping craft record of the El Niño-Southern Oscillation [ENSO].”

A washed and sorted marine sediment sample from the Eastern Equatorial Pacific, showing a tropical assemblage of foraminifera shells, which can be used to infer past sea surface temperatures, hydrology, and climatic variability. (Courtesy of Celeste Pallone)

Climate change threatens El Nino and other ages-old weather systems with severe disruptions. ENSO varies on 2–7 year timescales and has major influences on temperature, wind patterns, biological productivity and rainfall across the tropical Pacific and far beyond. This also includes crop yields, floods and droughts at multiple locations, said Jerry McManus, field researcher and professor at Columbia’s Department of Earth and Environmental Sciences and Lamont-Doherty. Understanding the baseline influences on this system is key to gauging how it may be altered through climate changes.

The latest report from the U.N.’s International Panel on Climate Change expresses continued uncertainty about how the El Niño-Southern Oscillation will respond to continued warming, although the consequences that play out in the global water cycle are likely to be greater (more rain and flooding in some areas, with increased drought in others). South American countries such as Peru rely on the periodic El Niño to bring warmer ocean waters and rainfall. The uncertainly over El Niño is unsettling. Additionally, the Special Report on the Ocean and Cryosphere in a Changing Climate projected that over the 21st century, the ocean will transition to unprecedented conditions with increased temperatures, further acidification and oxygen decline.  It predicts more frequent marine heatwaves along with extreme El Niño and La Niña events.

Pallone is seeing how she can reconstruct the oceanography of the eastern equatorial Pacific Ocean (the region of the open ocean directly south of Mexico and Central America) during a particularly interesting time in Earth’s past as she reported at the annual Comer Climate Conference, an international gathering hosted in southern Wisconsin but held virtually this fall.

According to WHO, the warming of the central to eastern tropical Pacific Ocean in the El Niño 2015-2016 event is affecting more than 60 million people, particularly in eastern and southern Africa, the Horn of Africa, Latin America and the Caribbean and the Asia-Pacific region.

El Niño is an oceanic climate pattern that characterizes unusual warming of surface waters in the eastern tropical Pacific Ocean. Considered the warm phase of a larger phenomenon called the El Niño-Southern Oscillation, the system marks a periodic warming of ocean surface temperatures. Its opposite, La Niña, is marked by an unusual cooling of oceanic surface temperatures. El Niño brings drier warmer weather to the northern United States and wetter conditions to the south. Arriving in the Americas around Christmas time in the cycle described below, it was given the name El Niño (meaning Little Boy or the Christ child) by Spanish fishermen.

Each climate pattern lasts about 9-12 months, and both tend to develop during the spring (March-June), reach peak intensity during the late autumn or winter (November-February) and then weaken during the spring or early summer (March-June) according to the National Oceanic and Atmospheric Administration.

“If you have a strong El Niño event, that might be followed by a strong La Niña event as well – but it is a consistent oscillation that we’ve observed,” Pallone said.

El Niño/La Niña’s hydrological effects are the most important implications on the human population. It can affect rainfall patterns impacting agriculture or even flooding and monsoonal seasons. With satellite measurements of sea surface temperature since the 1980s, there are historical records that indicate the same kind of variability that we observe today suggesting that the ENSO system has been occurring for certain at least the past several thousand years, perhaps even more.

“If we can kind of identify periods that had recurrent warming episodes, for example, or a really large range of temperature variability, we can associate those periods with stronger or more frequent El Niño events,” Pallone said.

McManus highlighted the importance of why Pallone chose to focus on a particular time period, Marine Isotope Stage 5. The marine isotope stages offer a way of tracking ice ages and the periods between them based on the oxygen isotopes found in sediment cores.

“MIS5 was approximately 130,000 to 70,000 years ago and the last interglacial interval that was subsequently followed by a major global ice age, and then the deglacial warming that led to the Holocene interglacial interval of the last 10 or 11 thousand years, the time when all of human agriculture and civilization has developed,” McManus said.

He emphasized that MIS5 is the interval of time when Earth was last as warm as it is today before the most recent ice age, offering the potential to provide insights into natural variability during a warm interval. “The 60,000 years of MIS5 were characterized by three large cycles in the seasonal distribution of sunlight based on the progression of the seasons around Earth’s elliptical orbit,” he said. This time period can help differentiate between natural climate events and what is going on now because of the climate similarities between the time periods of past and present.

Pallone received her undergraduate degree in environmental science at Barnard College. She earned an MA and is a current Ph.D. student in the Department of Earth and Environmental Sciences at Columbia University and the Lamont-Doherty Earth Observatory. She is a paleoceanographer and isotope geochemist with an interest in tropical dynamics during past glacial cycles. (Courtesy of Celeste Pallone)

Pallone’s research is tri-fold. She uses multiple methodologies to reconstruct the surface and subsurface oceanography of the eastern equatorial Pacific Ocean during a particularly interesting time in Earth’s past, according to McManus.

“She makes many measurements of the oxygen isotope ratios in individual specimens of surface-dwelling planktonic foraminifera shells preserved in deep-sea sediments deposited at that time to learn about the temperature each one experienced during its month or so lifetime, and to compare the range of temperatures that characterized different intervals in the past,” he said. “That tells us something about El Niño-Southern Oscillation (ENSO) variability.”

Another piece of her research is an analysis of multiple specimens of foraminifera species that live at a range of depths below the sea surface to assess their shells and biology as a way to assess where and how fast the temperature changes beneath the surface ocean, hallmarks of El Niño and La Niña events. She studies thermocline structure as another clue to temperature change. The thermocline is the transitional layer between warmer mixed water at the ocean’s surface and cooler deep water below.

Pallone also measures uranium, thorium and protactinium isotopes in the bulk sediment to estimate the amount of material that rained down due to biological productivity in the past.

“A shallower thermocline means that more nutrient-rich waters were moving toward the surface ocean at a particular time, potentially enhancing productivity,” McManus said.

Ultimately, by combining these three main methods, this enables Pallone to make a richer and more robust reconstruction of the ocean state in the EEP at different times throughout history.

The strength or frequency of an El Niño event can be influenced by small changes in Earth’s orbital geometry, with the main factor being changes in solar insulation that are driven by orbital shifts. Teleconnections, climate anomalies related to each other over long distances, also come into play because of how the atmosphere and oceans talk to each other.

“Because of the global circulation of the atmosphere in the ocean, if you have an event happening in the equatorial Pacific, for example, you’ll have effects in other parts of the world,” Pallone said.

Pallone started her research thinking that by using the foraminifera as a proxy and the MIS5 time period, she could create a good analog for modern warning.

“If we can reconstruct the environment during [MIS5], maybe it will inform about what changes could be coming in the future,” she said. “This, with most comparisons between the paleo record and the modern, we’re going to have kind of changes in temperature that might have been or that might be quicker than anything that we’ve seen in the past. But the past is still a useful analog for what could happen in the system.”

For the future, global efforts are needed to curb climate change. At the 2021 Glasgow Climate Conference, the United Nations called for a worldwide response to accelerate climate action to limit global temperature rise at a 1.5 degree C tipping point. The goal called for cutting global fossil fuel emissions by 45% compared to 2010 levels and doing so by 2030. The goal was not adopted.

Going forward, U.N. Secretary-General António Guterres deemed that the world is in emergency mode, meaning we must end fossil fuel subsidies, phase out coal, put a price on carbon, protect vulnerable communities, and deliver the $100 billion climate finance commitment.

Pallone’s research is a small but crucial step in reaching toward this goal.

El Niño events are the dominant source of like this kind of decades scale climate variability today,” Pallone said. “It’s unsettling that we’re not so confident in what could happen to them in the coming years or in the coming century.”

Photo at top: El Niño is anchored in the tropical Pacific, but it affects climate “downstream” in the United States. This shows the U.S. impacts of the climate patterns. (NOAA)

Carly Menker is a health, environment and science reporter for the Medill News Service and a Comer Scholar at Medill.  Follow her on Twitter @carlymenker.

COLDEX: The search for Earth’s oldest ice and new climate solutions

COLDEX: The search for Earth’s oldest ice and new climate solutions

By Christian Elliott, Dec. 9, 2021 –

Even summer days are cold in the Allan Hills Blue Ice Area, a meteorite-strewn expanse of glacier flanked by mountains at the eastern edge of the Antarctic ice sheet near the McMurdo Station research center.

Jeff Severinghaus, a paleoclimatologist at the Scripps Institute of Oceanography, and his colleagues at Princeton University discovered here in 2017 a 2.7-million-year-old chunk of glacial ice containing bubbles of trapped air from Earth’s ancient atmosphere.

That ice turned out to be contaminated by modern air, destroying its link to climate conditions millions of years ago. But the discovery reinvigorated the quest in the ice core science field to find the world’s oldest ice. Right now, the continuous record from a single ice core goes back only about 800,000 years.

Ed Brook operates a saw in Antarctica, slicing an ice core into smaller pieces. (Courtesy of Ed Brook)

In coming years, the world will be a much warmer place – average temperatures will increase by 2 to 3 degrees Celsius (3.6 to 5.4 degrees Fahrenheit), and arctic temperatures will rise by twice that rate. Over the next 10 years, paleoclimatologists hope to extend the ice core record back to 3 million years ago, when they know from climate clues in deep sea sediment cores that the Earth was last that warm. As the planet heats up today, many questions remain. How bad will hurricanes get? How frequent will forest fires become? How high will seas rise?

“The only practical way to know the answers to these questions is to get ice cores that are 3 million years old,” Severinghaus said. “It’s the only way to look into our future and see what we’re in for.”

Severinghaus has spent the last 25 years in Antarctica and in his lab in California studying the composition of gases in polar ice. Ice cores, he said, are key to understanding how Earth’s climate changes with varying levels of atmospheric carbon dioxide.

“There’s no other way to get a sample of the ancient atmosphere, other than the air bubbles in ice cores,” Severinghaus said. “From the ice cores, we learned that carbon dioxide concentrations have never been as high as they are today.”

The natural atmospheric carbon dioxide concentration over the last million or so years was 280 parts per million during warm spells and 180 parts per million during the cold snaps of ice ages. Today, CO2 levels hover at an unprecedented 420 parts per million due to human-generated fossil fuel emissions.

A new collaborative global effort is hot on the trail of the ancient ice, Severinghaus reported at the annual fall Comer Climate Conference, held virtually this year on Oct. 4-5.


Ed Brook, a paleoclimatologist at Oregon State University, received the good news in Februrary – the National Science Foundation selected his proposal for an ice-core-focused Science and Technology Center he calls COLDEX, the Center for Oldest Ice Exploration.

Over the prior two years, Brook brought together 30 of the nation’s leading paleoclimatologists representing 13 universities to jointly apply for the grant, which includes $25 million in funding over five years with a likely extension to 10 years and $50 million in total. Brook said the center represents the ice core field finally uniting a “critical mass” of researchers to justify such a massive investment in paleoclimate research.

Ed Brook presents COLDEX’s goals at the virtual Comer Conference on Oct. 4.

“It was so rewarding, because the right collaborators really stepped up and were interested in making this happen,” Brook said. “But it’s not for the faint of heart to try to organize this many people.”

As the Earth continues to warm, the race to find Antarctica’s oldest ice and understand historic climate change is accelerating – across the continent, the EU, Japan, Australia and Russia also are beginning multimillion-dollar drilling operations, and China’s effort has been underway, with slow progress, since 2012.

With its unprecedented level of funding, COLDEX’s explicit goal is to drill a single continuous deep ice core 1.5 million years old that is likely to be between 1.5 and 2 miles long and then extend the record back further to 3 million years through a composite of discontinuous “snippets” of ice from across the continent. Even though the Antarctic sheet is 2 miles thick in some places, it flows, melts and fractures over time, so researchers think 1.5 million years is the limit for a single core in one location. The oldest ice tends to exist in chunks at the windswept rocky edges of the sheet, like at the Allan Hills site.

“When you get back to 3 million years, there’s no ice that’s still intact stratigraphically – it’s all chopped up and mixed out of order, like a deck of cards that’s been shuffled,” said Severinghaus, who’s a co-principal investigator on COLDEX.

“These patches are out there,” Brook said. “But we don’t know exactly where they are or how many of them there are.”

Severinghaus compares reconstructing the ice core record to an archaeologist reassembling pieces of broken pottery to build a whole. Thanks to advances in geochemistry – paleoclimatologists can now study ancient atmospheric changes using argon, nitrogen, krypton and xenon isotopes in addition to the less accurate oxygen isotopes used in the 1970s – and the fact that atmospheric gas composition is the same throughout the world at any given point in time, COLDEX researchers can put together hundreds of puzzle pieces of ice from across Antarctica in the correct historical order.

McMurdo Station (USAP South Pole Webcam)

“We’re pretty confident we can construct a continuous composite record of the ancient atmosphere,” Severinghaus said. “It’s just going to be a bit of detective work.”

Drilling the 1.5-million-year-old deep ice core might prove just as challenging. Drilling ice cores is a slow, expensive process that requires heavy equipment. Researchers must travel inland, far from McMurdo Station, and establish a base camp where they’ll live and work for the season, which lasts the austral summer – October to February – when the sun never sets. During the winter, temperatures sink to -50 degrees Celsius (-58 degrees Fahrenheit), and the continent plunges into continuous darkness.

“It’s like being at sea,” Brook said. “There’s nothing to see except for snow. And it’s cold. The work is hard.”

Drilling rigs cut through the ice sheet a few meters at a time, and researchers hoist out heavy sections of core as the drill descends. It’s a slow, repetitive process. A 3,000-meter core (more than 1.8 miles) could take up to three seasons – three years – to complete.

The challenge, then, is to find an inland site with deep and old enough ice to justify setting up the COLDEX drilling camp. But much of the deep interior of the Antarctic ice sheet where that old ice likely is has never been mapped – scientists don’t know how deep the ice is.

“It’s just a blank spot on the map,” Severinghaus said. “So, we’re doing basic exploration at this point.”

The first five years

The COLDEX initiative kicked off in earnest in September. Brook is currently hiring researchers, coordinating with NSF logistics contractors to organize trips to Antarctica and building websites and lab spaces. Initial fieldwork – including testing a new fast thermal melt probe called Ice Diver in Greenland – is set to begin in 2022.

A staff member retrieves an ice core at the National Ice Core Lab in Denver, Colorado. (NSF NICL)

While some scientists – including Severinghaus and the Princeton team – continue searching for chunks of old ice at the ice sheet’s fringes and drill rapid 100-meter shallow cores there using Severinghaus’ Rapid Access Ice Drill, others will begin reconnaissance work to find the best site for the 1.5-million-year-old core.

“We’re going to be doing airborne radar echo sounding with new technology in a broad region from the South Pole towards Dome A,” an ice coring site, Brook said. “We’re looking to gather data that would help us put teams on the ground to do detailed radar in specific locations.”

Antarctic “domes” are the highest points on the ice sheet – locations where steady snowfall piled up over thousands of years to create particularly thick ice ideal for drilling old cores. A European team extracted the 800,000-year-old record core in 2013 at Dome C. Japan plans to drill for a 1.5-million-year-old core at Dome Fuji, Russia at Dome B, and Europe and Australia at Dome C.

Recent advances in aerial ground-penetrating radar make it possible for scientists to detect the thickness of the ice sheet as well as layers of dust impurities that indicate colder versus warmer periods – and thus the relative age of the ice. Ground teams will then follow up at two candidate sites with the Ice Diver reconnaissance drill, which can date ice quickly using a laser that detects dust variations, to narrow the choice down to one site.

“We want to know before we get into the $50 million logistics of drilling a deep ice core that the target ice is really there,” Severinghaus said.

The second five-year period will be dedicated to drilling and extracting that 1.5-million-year-old deep ice core and sharing it with the entire field for data analysis.

That core will also help scientists answer the mystery of the Mid-Pleistocene Transition. Around 1.2 million years ago, the length of the transition between cold and warm climate periods abruptly shifted from 41,000 to 100,000 years. Scientists think changes in atmospheric carbon dioxide were to blame, but an older core would provide proof.

Diversifying polar science

COLDEX has another priority as well. As of 2020, only 10% of doctoral degrees in geoscience went to people of color. Faculty of color only hold 3.8% of tenure-track geoscience department positions. It’s a continuing problem, and one that’s received repeated coverage in the journal Nature in recent years.

“Earth science has a diversity problem.” Brook said. “Some other fields have made progress, but that’s just not true in the earth sciences. And polar science is near the worst end of that spectrum, at least anecdotally. The exploration of Antarctica and Greenland has been perceived as a white male thing for quite a while.”

Ed Brook works on ice core gas extraction equipment in his lab at Oregon State University. (Courtesy of Ed Brook)

That’s where the second half of COLDEX comes in – diversifying the ice core field by establishing partnerships with a variety of minority-serving organizations to combat stereotypes and form new pipelines into the field and directly into COLDEX research work over the next 10 years.

“So, it’s only half about finding the oldest ice on the planet.” Severinghaus said. “The other half is doing public facing diversity, equity, inclusion and outreach.”

For example, in the past 40 years, only 20 Native American women earned geosciences doctorates. Sarah Aarons, a paleoclimatologist and Alaska Native at Scripps, will lead a partnership with the Alaska Native Science and Engineering Program to recruit Alaska Native students into the geosciences and, through the NSF’s Research Experiences for Undergraduates program, involve them directly in COLDEX.

“We know the climate is changing twice as fast in the Arctic, and so having Alaska Native people who are experts in climate and the environment in positions in academia or government who know what’s happening in the region they’re from is really, really important,” Aarons said.

Stereotype inoculation theory states that people tend to choose to mentor other people who come from a similar racial or ethnic background or share lived experiences. With the polar sciences dominated by white male researchers, that’s a problem for recruiting new students.

“So, we also plan to do work within our own community to try to understand what kinds of biases we may have and how to overcome those and make our community more welcoming,” Brook said.

“The exciting thing about COLDEX is it’s bringing together a group of people from a really wide variety of research backgrounds into the same room who are all committed to the same goal – finding the oldest continuous ice core record – and combining our expertise to tackle that question,” Aarons said.

In November, world leaders gathered in Glasgow for the UN’s COP26 climate change conference. They were shown a vial of air from 1765, the beginning of the industrial revolution, extracted from Antarctic ice and a section of an ice core, ancient air bubbles slowly, audibly popping as it melted away in front of them. It was a powerful and urgent illustration of both polar ice’s fragility and its ability to describe our ancient atmosphere – where we’ve been and where we’re headed. Through COLDEX, our nation’s paleoclimatologists hope to provide the clearest picture yet.

Photo at top: Jeff Severinghaus (L) and fellow COLDEX participant John Goodge hold an ice and rock core recovered during a test of rapid drilling equipment designed for ancient ice reconnaissance. (Courtesy of Jeff Severinghaus)

Christian Elliott is a science and environmental reporter at Medill. You can follow him on Twitter at @csbelliott.

Into the unknown: Exploring caves to uncover climate change clues

Into the unknown: Exploring caves to uncover climate change clues

By Christian Elliott and Brittany Edelmann, Dec. 8, 2021 –

Nearly 20 years ago, then Ph.D. student Gina Moseley walked into a bar in Bristol to meet fellow members of the University of Bristol Spelæological Society caving club. An older caver talked with her over drinks about some small caves in northeastern Greenland he’d always dreamed of organizing an expedition to explore. But, “logistically, it’s a nightmare to get out there,” said Moseley, now a professor in the Institute of Geology at the University of Innsbruck in Austria. The caver gave her all the papers he’d collected on the caves, and for years she kept them filed away.

Much later, a 1960 article by U.S. military geologists among the papers caught her eye. In their search for prime airfield locations, the geologists discovered caves with interesting geological features — crystalline calcite, stalagmites and flowstone deposits. To Moseley, that was proof Greenland’s caves contained something critical to scientists’ understanding of Earth’s ancient climate.

Moseley took her first steps into caving years earlier with her mom on a holiday trip when she was 12. She loved it. As she started grad school in Bristol, she discovered she could bring together her fascination with caves and her interest in studying paleoclimate to understand how future climate change — pushed by fossil fuel emissions of human activities — will affect the Earth.

Caves are normally “not altered or impacted by other processes” and “they’re so well-preserved over thousands of years,” Moseley said. That makes them a great location for climate research and creating records that can function as important analogs for future climate change.

The 2021 Comer Climate Conference on Oct. 4 – 5 brought together scientists from around the world, including Moseley and fellow paleoclimate researcher Kathleen Wendt.

Devil’s Hole

“Devils Hole was where it all began. That was the start of cave paleoclimate research,” Moseley said. Paleoclimate scientists first rappelled down into the deep, narrow cave in the Amargosa Desert in southwest Nevada in the late 1980s.

Using cores of the thick calcite crusts on the cave walls, which accumulated steadily over time, researchers reconstructed 500,000 years of climate history here with Uranium-thorium dating. Uranium-thorium dating provides insight into when a rock was formed– giving a date to the origin of the rock.

Devil’s Hole was also where Moseley and Wendt, who has her Ph.D. from the University of Innsbruck in Austria, got their start in cave paleoclimate science. In 2017, they returned to Devils Hole to extend the climate record further and validate the older results.

In their research Moseley and Wendt focused on oxygen isotopes, which provide temperature information about historic temperatures. During ice ages, a heavier isotope of oxygen forms at higher levels than during warm spells.

Wendt is getting ready to submit a new paper on the oxygen isotope record from Devils Hole. By showing the fluctuation in types of isotopes, heavier versus lighter forms of oxygen, this will give “clues into changes in temperature and a little bit about the source of precipitation over time,” Wendt said.

They found the water table dropped below modern levels during the last interglacial, 120,000 years ago, when Earth’s orbit brought the planet closer to the sun. That time period is an analog for southern Nevada’s hotter and drier future that will be accelerated beyond natural planetary fluctuations with human-forced extremes of climate change.

“Studying the paleoclimate tells us what nature is capable of,” Wendt said.

The Greenland caves

Paleoclimatologists who focus on caves often study speleothems — mineral deposits formed by dripping water. Protected within caves from the elements, these dripstones (stalagmites and stalactites) and flowstones grow as layers of calcium carbonate carried by rainwater add up over hundreds of thousands of years.

One of the flowstones Moseley found in the caves was specifically mentioned in the 1960 paper that inspired the expedition.

In Greenland, now a rainless polar desert, speleothems formed during a time when the island’s climate was warmer and wetter. By collecting and sampling speleothems, Moseley can reconstruct that ancient climate period as an analog for the future, when Greenland will once again be warmer and wetter.

Over millions of years due to orbital changes, Earth’s climate alternates between warm and cold periods — interglacials and ice ages called glacials. Paleoclimatologists rely on air bubbles in cores taken from ice sheets in Greenland and the Antarctic to study the composition of the ancient climate’s atmosphere, but there’s a problem — during warm periods, the ice sheet melts. That’s where the caves come in.

“So the caves offer the polar opposite of what the ice cores do because the ice cores tend to be cold-based climate records and the caves can give us warm-based climate records. So, we get to the two different parts together,” Moseley said.

That’s a common theme in paleoclimatology — no one climate proxy shows the big picture. To fully understand Earth’s ancient climate, scientists must piece together hundreds of pieces from data from sources across the world.

“If you have one cave in one location, that’s kind of interesting. But if you can relate that to other caves in other locations, ice cores in other locations, deep sea sediments in other locations and get the whole picture, that’s where it really gets interesting. That’s where we can answer the big questions and tackle the big issues,” Moseley said.

As the Arctic continues to warm at twice the rate of the rest of the world, understanding what warm and wet historic climate periods were like can help scientists know what to expert in the imminent future.

This leads to Moseley’s next adventure in 2023, where she will explore completely untouched caves in Northern Greenland. This was only made possible with an award from Rolex — which provides funding for such an endeavor.

Christian Elliott and Brittany Edelmann are science and environmental reporters at Medill. You can follow them on Twitter at @csbelliott. and @brittedelmann.

Climate change pushes precipitation — and ability to predict it — to its limits

Climate change pushes precipitation — and ability to predict it — to its limits

By Sarah Anderson, Dec. 7, 2021 –

Primed by a drought that has lasted longer than the 1930s Dust Bowl, wildfires scorched over 5 million acres of land in the western United States this year. The water level of Lake Powell is dipping dangerously low amid the severe dry spell, threatening the hydroelectric power it generates.

On the other side of the country, a record-breaking 2020 hurricane season produced so many tropical storms that the list of 21 names for them had to be supplemented with Greek alphabet letters for just the second time in history. Hurricane Laura alone caused 42 deaths and almost $20 billion in flood damage.

Climate change is pushing precipitation to both extremes. The elevated annual mean temperature in the United States is accompanied by higher levels of rain and snow in the eastern, southeastern and midwestern regions of the country and decreases in precipitation in the western and southwestern areas, according to the National Oceanic and Atmospheric Administration (NOAA).

“The basic result is that we (will) see more floods and more droughts,” said Richard Alley, a climate scientist and professor of geosciences at Pennsylvania State University, during the annual 2021 Comer Climate Conference, held virtually this year. “You get more intense events in a warmer world.”

As the annual mean temperature increases across the United States, precipitation concentrates in certain regions. (Image source: NOAA)


Climate change has heightened the need to predict and prepare for extreme precipitation events, but it has also impaired the ability to do so. According to NOAA, the United States’ average seasonal precipitation skill — the accuracy in forecasting the amount of precipitation over an upcoming season in a specific region — has declined in recent years.

Precipitation skill varies for different areas, in part because naturally occurring cycles in ocean temperature have a well-documented effect on precipitation trends. El Niño, a climate phenomenon resulting from a warming of the central and eastern Pacific Ocean that occurs every three to seven years on average, has a consistent impact on rainfall in the places along its path each time it strikes.

Seasonal precipitation skill is “actually pretty good in places that are affected by El Niño because we can predict El Niño, and El Niño statistically affects weather patterns,” said David Battisti, a professor of atmospheric sciences at the University of Washington.

The U.S. seasonal precipitation skill has deteriorated since 2013. (Image source: NOAA)

Elsewhere, however, technology has struggled to keep up with new variables as the climate evolves. The impact of climate change on precipitation — and precipitation skill — can be largely traced to the ocean, which stores approximately 93% of excess heat driven by emissions from fossil fuel use, according to the Intergovernmental Panel on Climate Change.

“If you heat the planet, you get more evaporation from the ocean, just like if you heat a pan on your stove, you start to get steam coming off of it,” Battisti said. The additional water vapor in the air means when conditions are right for rain, it rains harder.

As the relationship between rising ocean temperatures and precipitation became clear, the U.S. National Weather Service realized it needed to incorporate ocean processes into its forecasts, said Joellen Russell, a climate scientist and oceanographer at the University of Arizona, at the Comer Climate Conference. However, rather than developing a new climate model that integrated ocean from the start, the ocean element was tacked onto the existing atmosphere component.

“They coupled it, but it wasn’t really designed to be coupled,” Russell said, resulting in a weather simulation that cannot account for the full network of interactions between ocean and atmosphere. It more closely resembles a layer of red painted over a layer of blue than a pointillist blending of red and blue dots that appears purple.

The accuracy of U.S. precipitation prediction tools is also limited by the lack of information on ocean conditions due to shortcomings in operational oceanography, Russell said. For example, orbital satellites often sample from confined and redundant areas, collecting spotty real-time data to feed into the model.

While some scientists focus on how to gather and use current data to further improve seasonal precipitation skill, other researchers are looking to the past to predict the long-term impacts of climate change on precipitation in specific regions. Dylan Parmenter, a Ph.D. student in the Department of Earth and Environmental Sciences at the University of Minnesota, presented his work studying the chemical composition of stalagmites to reconstruct rainfall patterns in the Amazon at the Comer Climate Conference.

Dylan Parmenter collects a cross section of stalagmite from a cave, which shows tree ring-like features corresponding to different time points. (Images courtesy of Dylan Parmenter)

Stalagmites form when water vapor carried from the ocean combines with the soil at a cave site and drips onto the floor of the cave. In this way, “stalagmites are kind of like fossilized precipitation,” Parmenter said. The oxygen atoms in the water vapor exist as two versions — one heavier and one lighter. If it rains as the water vapor cloud travels, the heavier oxygen atoms fall to the ground with the rain before reaching the cave. By measuring the ratio of the two types of oxygen in a sample of stalagmite, Parmenter can estimate the precipitation conditions when the stalagmite was created. To determine the age of the sample, he measures to what extent uranium atoms in the stalagmite have decayed, expelling some of their subatomic particles.

These ancient rainfall records can help scientists understand the effect of past climate patterns on precipitation, providing a useful reference point when predicting the impact of modern climate change.

“If we want to know how precipitation in a certain region is going to change from climate change, there’s nothing to compare that to,” Parmenter said. “Our work is going back and saying: With these natural climate change processes in the past, how did it react?”

While Russell acknowledges there is no time in history perfectly representative of the current climate conditions, the fundamental insight gained from research like Parmenter’s will be critical in informing responses to climate change.

“We are in the undiscovered country of the future, as Shakespeare put it. So, no, it’s not going to be exactly the same as any previous (time),” she said. “But being able to look at how these mechanisms have worked in the past can help us accelerate the learning that is going to be required to do the preventing, the mitigating and the adapting.”

Featured photo at top: A satellite image captures Hurricane Laura’s landfall. (Image source: NOAA)

Sarah Anderson is a health, environment and science reporter at Medill and a Ph.D. chemist.  Follow her on Twitter @seanderson63.

Melting tropical glaciers threaten freshwater sources while sea ice melt accelerates rising oceans

Melting tropical glaciers threaten freshwater sources while sea ice melt accelerates rising oceans

By Sarah Anderson, Nov. 16, 2021

“Tropical glacier” —  the term sounds like an oxymoron and, due to climate change, it might become one.

These bodies of ice nestle in the mountain ranges of tropical regions, providing a major source of freshwater and tourism revenue. But studies predict most tropical glaciers will disappear within the next 10 years taking critical water resources with them.

“It’s hugely important to understand the rate at which these glaciers are melting,” said Alice Doughty, a lecturer of Earth and climate sciences at the University of Maine.

Doughty and Meredith Kelly, a professor of Earth sciences at Dartmouth College, are developing a model to investigate tropical glacier melt in places such as the Rwenzori Mountains in Uganda and the Sierra Nevada del Cocuy in Colombia. They presented their findings at the virtual 2021 Comer Climate Conference, an annual event usually held in southwestern Wisconsin.

Glaciers sand down the rock beneath them as they melt, acting “sort of like bulldozers,” Kelly said. The debris piles up, depositing a series of ridge-like features called moraines at the glacier’s retreating boundaries. Kelly examines satellite images of a glacier site to identify moraines the glacier left behind, then analyzes samples of rock to determine when the moraines were created. By measuring a type of beryllium atom that accumulates in the rock as it is exposed to Earth’s atmosphere, Kelly can approximate how long ago the rock was freed from the ice’s hold to form the moraine. Collectively, this information allows her to generate a map of the size and shape of the glacier at a specific time in the past.

Moraines in the Sierra Nevada del Cocuy photographed by satellites (left- map and data courtesy of Jordan Herbert, M.S. student at Dartmouth College) and on the ground (right- image courtesy of Gordon Bromley, professor at the University of Maine).


Doughty then works to develop a computer model to simulate how climate variables interact to produce the glacier. She tries to “grow the glacier,” adjusting temperature, precipitation and other inputs until the glacier output matches Kelly’s map.

Data from any nearby weather stations provide a useful starting point; observing whether current climate conditions yield the modern glacier helps her evaluate the model. When the simulation is optimized, Kelly and Doughty will be able to use it to predict the effect of climate change on glacial melt.

“Once we calibrate the model, we can just as easily make things warmer,” Doughty said. “And so we can have estimates like in the Rwenzori, one degree of warming and those glaciers are gone.”

Other scientists are interested in developing similar models for the melting of sea ice, “a really big part of the climate system,” said Ed Brook, a professor of Earth, ocean and atmospheric sciences at Oregon State University.

Sea ice helps insulate the ocean from heat and gases in the atmosphere and contributes to sea level rise when it melts, but it doesn’t leave behind the same physical record as glaciers. While seasonal sea ice melting can be tracked using IP25, an organic molecule produced by algae that grow along the receding ice edge, the presence of permanent sea ice in the past has remained elusive.

“We don’t have a very good method for reconstructing how much sea ice there was at any particular time,” Brook said.

Frank Pavia is analyzing chunks of Arctic Ocean floor gathered in the mid-1990s, but he has journeyed to other ice-covered seas to collect similar samples. (Image courtesy of Frank Pavia)

Frank Pavia, a postdoctoral researcher in geological and planetary sciences at the California Institute of Technology, presented his research at the Comer Climate Conference, exploring a new way to monitor this more stable sea ice cover. His method relies on interplanetary dust particles, the solar system’s version of dust that rains down on Earth from outer space.

Interplanetary dust particles deposit a light type of helium atom onto the sea floor. If the surface of the ocean is blocked by ice, however, the particles (and the helium) can’t enter the water. Pavia is examining whether the amount of helium in the ocean floor can be used as a measure of sea ice cover. To account for any differences in helium levels due to changes in how fast atoms settle to the sea floor, he also measures a special thorium atom that is produced inside the ocean and sinks to the bottom at a constant rate, regardless of ice cover.

To test his method, Pavia acquired samples of the floor of the Arctic Ocean from the Last Glacial Maximum, one period of well-characterized sea ice cover in the Arctic. The age of the samples had been previously determined by measuring a radioactive form of carbon in the shells of tiny marine organisms that indicates when they were alive.

When sea ice cover was thick, Pavia detected high amounts of thorium but low levels of helium, demonstrating that while atoms were efficiently burying in the sea floor, helium couldn’t access the ocean due to the sea ice. When there was no sea ice cover, he measured similar signals for both thorium and helium, revealing that the helium atoms were successfully deposited into the ice-free ocean. Pavia is also interested in seeing if the period of melting in between gives a surge in helium, corresponding to an influx of interplanetary dust particles that accumulated on top of the ice over time.

While accurate measurements will require that the dust particles are evenly distributed in the ocean floor rather than concentrated in specific pockets, the approach “has a lot of promise,” Brook said. The prospect of detecting nonseasonal sea ice melting — an event that leaves very few fingerprints — via a helium spike could be a major advantage of the method, he said.

“It’s potentially very important, because if the pulse of particles was the signature of melting a bunch of permanent ice, then you would have a sign of that process, which would be very hard to see other ways,” Brook said.

After further validation, Pavia plans to use his method to reconstruct poorly understood sea ice patterns during past periods of warming in the Arctic. Like Kelly, he aims to provide a map that other researchers can use to test and refine models that simulate sea ice melting as climate change progresses.

“The hope is to help improve the projections of sea ice coverage into the future in the Arctic,” Pavia said.

Featured photo at top: Meredith Kelly and Alice Doughty study the pace of melting of tropical glaciers like this one in Uganda’s Rwenzori Mountains. (Image courtesy of Alice Doughty)

Sarah Anderson is a health, environment and science reporter at Medill and a Ph.D. chemist.  Follow her on Twitter @seanderson63.

COVID-19’s minimal climate impact highlights need for momentous action now

COVID-19’s minimal climate impact highlights need for momentous action now

By Liam Bohen-Meissner, Jan 28., 2021

PODCAST  Global carbon dioxide emission dropped 7 percent worldwide due to a decrease in human activity after COVID-19 brought much of the world to a standstill. Despite this, the climate impacts of COVID-19 turned out to be negligible, with 2020 tied with 2016 as the hottest year on record. Global temperatures have risen 1 degree Celsius (1.8 degrees Fahrenheit) over the past decades and are expected to meet or exceed the 1.5 degree ceiling set by the Paris Climate Agreement by 2030 without drastic decreases in fossil fuel emissions..

If a global pandemic is not enough to put a dent in climate change, then what hope do we have? Local Illinois climate experts provide their insight on what changes must be made if we are to succeed in this battle with the climate crisis.

Liam Bohen-Meissner is a health and politics reporter at Medill.

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