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Pollution-laden dust storms are depositing black carbon on the Himalayas. New research from INSTAAR’s Karl Rittger and collaborators reveals the process.

Regional pollution is speeding up snow melt in the Indian Himalayas. That’s according to  from an international group of scientists including Indian Institute of Technology Madras civil engineering PhD student Amit Singh Chandel and INSTAAR research associate Karl Rittger.

  Three of the four largest river basins in the world lie in this region. Understanding this snowmelt is a key question.

- Chandan Sarangi

The study, published in the , reveals how dust storms pick up black carbon from heavily-polluted areas and deposit it in the mountains. Black carbon darkens the ice and snow, causing it to melt faster. 

It’s a key insight into a persistent problem. Dwindling ice in the Himalayas has long troubled researchers and decision makers in southern Asia. , and glacier loss could lead to water shortages and an increase in extreme floods.

“Three of the four largest river basins in the world lie in this region,”  said. “Understanding this snowmelt is a key question.”

The new study is the result of collaboration across scientific disciplines and international borders. The seeds were planted a few years ago. Sarangi’s lab had already published numerous mathematical models mapping perennial dust storms in Northern India. And they knew that black carbon was getting into the dust somewhere along the way. 

In order to paint a clearer picture, Sarangi looked to pair his modeling work with long-term measurements from the field. That’s how he found co-author , a senior research scientist at the Finnish Meteorological Institute. Hooda previously collected nine years of atmospheric measurements at a site in the Himalayan foothills. 

Hooda’s data, paired with Sarangi’s models, revealed two distinct types of storms. The first type brews in the deserts of western India and Pakistan and travels east at low elevations. These storms mix with pollution from the heavily-populated Indo-Gangetic Plains before reaching the Himalayas.

  You get a darkening of 26% versus 58%. The polluted dust events have double the impact. It’s still a human-induced impact, it’s just not a climate change impact.

- Karl Rittger

The second type of storm starts in the Saharan Desert and travels at higher altitudes. These storms pick up very little pollution.

The new model told the researchers where the dust storms were coming from and what was in them. Now the question was how the storms impact snow and glaciers. 

That’s where Rittger came in. In previous research, he had developed a model that could tease apart contributing factors to snow-darkening using satellite imagery. The team applied Rittger’s methodology to the dust storm models and once again validated the findings with on-the ground data.

The results were clear. The storms with high concentrations of pollutants melted more snow. 

“You get a darkening of 26% versus 58%.” Rittger said. “The polluted dust events have double the impact.”

Previous research on diminishing glaciers in the Himalayas has often focused on global warming, but the new findings reveal a second, more local cause. To Rittger, it’s a good reminder to look for regional environmental problems that might mimic or coexist with global ones.

“It’s still a human-induced impact, it’s just not a climate change impact,” he said.

The success of this study has all of the co-authors thinking about next steps. Rittger hopes to one day expand his  website, which provides automated readouts of snow characteristics in the Western US, to Asia. Sarangi hopes to establish more field sites.

“We need more measurements to characterize the aerosols reaching the Himalayas.” He said. “It’s increasing every day.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

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CU ��«����Ƶ Chancellor Justin Schwartz recently dropped in on INSTAAR, where he discussed the institute’s research strengths and potential collaborations at the university level.

CU ��«����Ƶ Chancellor Justin Schwartz recently dropped in on INSTAAR for a tour and meet-and-greet. It’s the first time the chancellor has visited the Institute since he was appointed last summer. 

After coming in from the cold, Schwartz joined INSTAAR leadership for coffee and conversation in INSTAAR Director Nicole Lovenduski’s office. The group discussed INSTAAR’s research strengths and potential collaborations at the university level.

Schwartz was affable and curious. His background as a nuclear engineer showed through his nuanced inquiries into INSTAAR’s work.

“He asked many insightful questions,” Lovenduski said. “He was a very engaged visitor.”

After coffee, the group continued on to INSTAAR’s Laboratory for AMS Radiocarbon Preparation and Research, where lab director Scott Lehman gave a presentation. Lehman focused on the lab’s innovative research carbon-14, a radioactive isotope of carbon found in the atmosphere.

Next, the group continued to the Stable Isotope Lab. There, lab manager Sylvia Michel gave a presentation on the lab’s efforts to trace carbon dioxide and methane emissions by measuring isotopes of carbon, hydrogen and oxygen in the atmosphere. 

Schwartz was joined by Senior vice Chancellor for Research and Innovation Massimo Ruzzene, who oversees INSTAAR as the dean of institutes. Ruzzene was glad to have the opportunity to introduce Schwartz to INSTAAR and to see some of the institute’s laboratories in-person.

“It was very informative and inspiring to see the real impact and excellence of the work at INSTAAR,” he wrote in an email following up on the visit.

Before departing, Schwartz and Ruzzene donned parkas and joined INSTAAR Faculty Fellows Bruce Vaughn and Bradley Markle in the Stable Isotope Lab’s walk-in freezer, where the researchers store ice cores from Greenland and Antarctica.

At the end of his visit, Chancellor Schwartz brainstormed with INSTAAR leadership about potential campus-wide collaborations. In particular, he showed a keen interest in tapping the institute’s expertise in climate and earth systems research.

“His visit unearthed new ideas about how INSTAAR might connect with campus-wide sustainability initiatives,” Lovenduski said. “INSTAAR is well-positioned to plug into these efforts — from monitoring and verifying emissions reductions through trace gas measurements, to our work understanding soil carbon storage and ecological conservation.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

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A refined mathematical model is now capable of predicting carbon inputs and outputs for freshwater lakes around the world, according to new research from INSTAAR’s Isabella Oleksy and collaborators. Their work could help scientists understand the role of freshwater lakes in the global carbon cycle.

Oleksy's most recent paper, which was published, tests and revises an equation that allows scientists to estimate the overall biological activity in a lake from limited data.

The equation  by a group of scientists, including Oleksy's co-author , in 2018. It’s a mathematical formulation of  — a longstanding theory in the field. Basically, the theory posits that you can estimate the total growth of phytoplankton in a lake from the color of the water and measurements of a few key nutrients. Phytoplankton is the basis of the marine food web, which makes it a good stand-in for lake productivity on the whole.

  Further refinements of a model like this might be used to generate estimates of how much carbon is being fixed by lakes annually

-- Isabella Oleksy

“This is a way to potentially be able to understand what algal biomass and water quality might look like in a bunch of different lakes, even when you can’t necessarily get out there and measure it,” Solomon said.

Oleksy's study is the first to test the model against real world data — quite a bit of it. Back in 2019, when Oleksy was a postdoctoral researcher at the , she put out a call for data at a meeting of the .

“I asked people, ‘Hey. I want to test this model, but we need observations from lakes around the world,’” she said.

Collaborators were eager to help out. With the help of 30 scientists at many different institutions, Oleksy gathered detailed measurements from 58 different freshwater lakes around the world. Then, she tested the model’s predictions against the data. The initial test was encouraging.

“The results were pretty realistic,” she said.

The next step was to make the predictions even better. Through a process called Monte Carlo analysis, Oleksy pitted the model’s predictions against the on-the-ground data. Where the model faltered, she added new parameters to improve it.

In the end, Oleksy and her collaborators created a model capable of estimating the conditions of freshwater lakes in a diverse range of locations and ecosystems.

According to Oleksy, the new model could have implications far beyond freshwater lakes. It elucidates one small element of the global carbon cycle — a cycle that has become a priority for scientists in the era of global warming.

Policy makers and researchers rely on global-scale models of the carbon sources and sinks to predict the Earth’s future climate and inform large-scale solutions for climate change. These models are vast and complex — they must take into account the inputs and outputs of diverse human activities, ecosystems and geologic phenomena. Oleksy and her collaborators hope that their new study can be used to eliminate some uncertainty from these estimates.

“There is a lot of uncertainty about the role of inland waters,” Oleksy said. “Further refinements of a model like this might be used to generate estimates of how much carbon is being fixed by lakes annually.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

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Michael Gooseff and collaborators are gathering the first-ever continuous, long-term water quality sample of the Colorado River's upper basin. INSTAAR senior communication specialist Gabe Allen joined them for three days on the river.

One vessel in particular stood out from the rafts of vacationers and fisherman that floated lazily through Ruby Canyon on a sunny fall day last month. The occupants had swapped the usual fish and tackle for binders, laptops and an assortment of pumps and devices all buckled together with ratchet straps.

Aboard the raft, U.S. Geological Survey groundwater hydrologist bottled river water samples and jotted down notes in a waterproof notebook. Behind him, INSTAAR faculty fellow Michael Gooseff manned the oars and kept a watchful eye on a collection of sensors strung on a pole that extended into the water from the back of the boat.

This is the tenth time Gooseff and his collaborators have rafted this stretch of river since 2018. The goal is to gather the first-ever continuous, long-term water quality sample of the Colorado River's upper basin. In 2023, the USGS awarded Gooseff’s team with funding for biannual surveys through 2026.

A new approach

While water quality data is usually limited to discrete monitoring stations posted every few miles along the river bank, Gooseff’s boat-mounted sensors capture data every 40-60 feet. He calls this sampling method “Lagrangian sampling” after the 18th-century mathematician Joseph-Louis Legrange.

“His idea was that you could take the perspective of a moving particle in the world and try to understand how it changed based on its surroundings — as opposed to sitting somewhere and watching the world change around you.” Gooseff explained.

Gooseff’s raft, or “floating sampling platform” as he likes to call it, is equipped to measure pH, temperature, conductivity, turbidity, dissolved oxygen and nitrate. Collectively, these measurements offer a detailed map of the character and contents of Colorado River water as it travels from Rocky Mountain National Park to the canyonlands.

“What we’re trying to do is to figure out, ‘where do we see systematic changes along the river,’” Gooseff explained. “And now we have a higher spatial resolution.”

Pinpointing water quality

The project has already reaped insights. In 2019, . The researchers were able to pinpoint sources of salts, nitrogen, turbidity and temperature fluctuation over time and space.

One particular finding offered important insight to river users. Somewhere around Grand Junction, Colorado, nitrate concentrations in the Colorado River increase. A signal like this is usually the result of agricultural runoff, but water managers weren’t sure exactly where the nitrate was coming from. Was it from the confluence with the Gunnison River, which hosts large farms upstream? Was it from local farms in the Grand Valley?

Gooseff’s data showed that nitrate levels spiked when the Gunnison entered the Colorado and then continued to climb as the river moved through the Grand Valley. The study elucidated, for the first time, how much nitrate was contributed by each source.

Gooseff hopes that findings like these can help water and land managers better solve issues as they arise. The upper basin is especially important because changes in water quality here can compound as the water travels to lower-basin states like California. Nitrate, which can lead to harmful algal blooms in high enough concentrations, is just one example.

“There’s a lot of the Colorado River watershed that has the opportunity to modify water quality before it gets to the end of the basin,” he said.

Understanding groundwater

This year, the floating sampling platform featured a new gadget. Newman brought along a portable mass spectrometer called a  that is capable of detecting precise concentrations of noble gases, like helium or argon, in the water.

The miniREUDI was more expensive than everything else in the boat combined, and is one of only two in the U.S., but it was worth it. By tracking helium along the Colorado, Newman can infer where salty groundwater is entering the river.

“The noble gases are an indicator of where there’s old groundwater discharge,” Newman explained. “We essentially look for the helium to show us where there might be influence of salts because the salinity of the Colorado River is one of the primary management concerns for downstream users.”

If the Colorado becomes too salty, it could prevent lower-basin users in California and Mexico from using the water for agriculture, industry or drinking water. Newman’s data will give water managers more information that they can use to map and prevent excess salinity.

Newman, Gooseff and other collaborators outlined their methodology and rationale for using miniREUDI in the boat . They hope to publish more results soon.

Click to zoom

Packing up

As Gooseff’s raft passed through the Black Rocks, a popular swimming, fishing and cliff-jumping spot in Horsethief Canyon, a fisherman waved from a nearby boat.

“You all are with the USGS?” he asked. “I use your data all the time.”

Because Gooseff’s research is funded by the USGS, any papers or datasets that come from it will be freely available to the public. The insights will be invaluable for land and river managers like the Bureau of Land Management. With any luck, they could help especially science-literate fishermen find a new honey hole as well.

By now, the floating sampling platform, oars and camping gear are packed away for the winter. But, it won’t be long before Gooseff heads back up to the Pumphouse Boat Launch to run the river during the high-flow spring season. As much as he relishes long days in the field and nights spent under the moonlight, the quiet months are just as interesting.

“The real reward is stepping back after our samples are analyzed and our data comes together and asking ‘what have we learned,’” he said. 

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

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Each year, more than 25,000 earth and space scientists from around the world convene for the annual convention of the American Geophysical Union. This year’s conference runs for a week on 9-13 December in Washington, D.C., and will feature talks and posters from INSTAAR’s faculty fellows, faculty research associates, postdocs and students. Our Institute’s contributions will span the globe, touching on Earth systems in the oceans, alpine and polar regions.

Research highlights, from Monday to Friday

Click any image to zoom

A sea-ice free arctic

“The first ice-free day in the Arctic Ocean could occur before 2030” — it’s a stark title for faculty fellow Alexandra Jahn’s latest paper, . Jahn will give an invited talk about her research during a Monday session. In it, she will detail her work to model the climatic conditions that could lead to an ice-free arctic in the near future. Her collaborator on this project was the Swedish earth scientist Céline Heuzé. Read more about this project in CU ��«����Ƶ Today.   

Woody encroachment into alpine tundra

Although woody encroachment has been well-studied in the arctic, less is known about its effects in alpine tundra. Katya Jay (INSTAAR affiliate and alum, now at NEON and CU ��«����Ƶ ESIL) and her co-authors have combined multiple imagery datasets with many other measurement types to try to understand how encroachment happens over time. The team included Katharine Suding, Will Wieder, and two CU ��«����Ƶ colleagues. Jay will present their findings in a poster session on Tuesday. For more about her recent research, .  

Alpine lake biomarkers in Wyoming

Lipid biomarkers preserved in lake sediment provide valuable information about past climate and environmental changes. One such class of biomarkers, brGDGTs, has proven its value as a paleothermometer and has promise for reconstructing other key environmental variables as well. INSTAAR research scientist Jonathan Raberg (also with University of Wyoming) will present his collaborative work to compare sediment brGDGTs with other environmental proxies in Wyoming alpine lakes.  

Warming and sediment on the Canning River

Faculty fellow Irina Overeem - with a team of mostly INSTAAR researchers, alums, and affiliates - spent the past two field seasons documenting changes on the Canning River in Alaska. She will speak about their research on Tuesday. The project investigates the transport of sediment and nutrients from the Alaskan permafrost out to the Arctic Ocean. Overeem and PhD student Josie Arcuri are also the stars of a new film about the project titled “Icy River” by ��«����Ƶ-based documentarian Ryan Vachon. .  

Carbon cycling in cold regions

Arctic rivers move, process and store an immense amount of organic carbon — carbon that has built up in the surrounding permafrost over millennia. Faculty fellow Suzanne Anderson will present a poster on Tuesday detailing her work to elucidate the carbon cycles, sources and sinks of these icy waterways. Her research sheds light on these poorly-understood systems during a time when climate change is impacting them on every level. Her collaborators include Irina Overeem, Robert Anderson, Marisa Repasch and Josie Arcuri.   

Snowmelt and subalpine forests

As the climate warms, subalpine forests experience longer growing seasons and more variable winter snow. In an invited talk on Thursday, faculty fellow Noah Molotch will detail his investigation into these important ecosystems over the past quarter-century. His work draws on decades of remote sensing data that shows the importance of snowmelt on ecosystem productivity. His collaborators include Eric Kennedy, John Knowles, Sean Burns and Peter Blanken.  

Marine heatwaves and ocean acidity extremes

PhD student Samuel Mogen, Nikki Lovenduski and collaborators take aim at predicting marine heatwaves and ocean acidity extremes in a . Their new model is adept at forecasting these acute events from months to a year in advance, with varying degrees of certainty based on the event type and location. Mogen will present the team's poster on Thursday in a session on climate variability and predictability. Read more about the forecasts in a recent INSTAAR news story.  

Flooding in the 21st Century

Faculty fellow Albert Kettner will give an invited tallk on Thursday during AGU’s “Changing Climate: Associated Natural Hazards and Impacts” session. He will focus on . His research documents changes in the magnitude and frequency of flooding under a specific climate scenario, in which emissions are reduced slowly. His collaborators include Sagy Cohen, Irina Overeem, Balazs Fekete, Robert Brakenridge and Jaia Syvitski. Read more about Kettner’s work in a recent INSTAAR news story.  

Microbes and methane growth 2020-2022

A new analysis from Sylvia Michel, Pieter Tans, Reid Clark, Jianghanyang (Ben) Li, and collaborators investigates the root cause of a recent atmospheric methane spike. Their finding suggests microbes have been emitting more methane than fossil fuels in recent years. Nonetheless, reducing fossil fuel consumption remains key to addressing climate change. Their work was recently . Michel will give an invited talk on Friday in a session on Isotopes of the Atmospheric Components. Read more about this study in CU ��«����Ƶ Today

Mountain hydrology and biogeochemistry

Presentations on 'Mountain hydrology and biogeochemistry in a changing world' are being held in honor of (INSTAAR Fellow Emeritus and Geography Professor Emeritus), who passed away in 2023. Presenters are invited to build on Mark's diverse contributions and address the question: What’s next for mountain hydrology? A total of 25 presentations will be made. Noah Molotch is the primary convener, assisted by Diane McKnight and Jennifer Morse, plus INSTAAR alums Paul Brooks (University of Utah) and Alia Khan (Western Washington University).    

Special events

Click any image to zoom

Monday 4:00 - 5:00 p.m. Exhibit Hall booth #328

Meet the editors of INSTAAR's journal AAAR

INSTAAR's peer-reviewed, open-access journal will be represented in booth #328 in the Exhibit Hall during the meeting. Stop by on Monday late afternoon to meet with our journal editors Anne Jennings and Diane McKnight as well as the staff at Taylor & Francis who publish and host the journal. AAAR primarily covers environmental science from modern to paleo timescales, with an emphasis on climate change in mountain and high latitude regions.

Monday 5:30 - 7:00 p.m. Dacha Beer Garden

Attend the INSTAAR happy hour

Our NewSTAAR committee is hosting an informal INSTAAR happy hour on Monday evening. All INSTAARs are invited, both current folks and alumni. Grad students and postdocs are especially encouraged to attend. The event will be held at the Dacha Beer Garden (Shaw, 1600 7th St NW #7), which has a variety of drink/food options and is within walking distance to the convention center. Committee members will be there until about 7:00 p.m., so drop by when you can.

Wednesday 6:00 - 8:00 p.m. Hall E

Celebrate INSTAAR's latest AGU Fellow

Michael Gooseff is among 54 scholars in the 2024 cohort of AGU Fellows. All have made exceptional contributions to their fields and will be celebrated at the Honors Ceremony on Wednesday evening in Hall E of the Convention Center (subsequent banquet requires a ticket and is in a different location). The honor is bestowed annually on less than one tenth of one percent of AGU members. Gooseff was selected for his exemplary leadership and for advancing our understanding of how a changing climate affects ecosystems and freshwater supply. Read more about Mike and his recognition in an INSTAAR news story.  

Additional presentations

More than 85 INSTAARs are participating in AGU 2024. Click an author name below to see their abstracts on the AGU website. For questions, email David Lubinski.

Categories

Each author’s name is followed by a bracketed number (signifying the number of abstracts they contributed to) and a series of short letter codes (signifying topics). The topic codes are as follows:

• A  Atmospheric Sciences
• B  Biogeosciences
• C  Cryosphere
• EP  Earth & Planetary Surface Processes
• ED  Education
• GP  Geomagnetism, Paleomagnetism & Electromagnetism
• GC  Global Environmental Change
• H  Hydrology
• NH  Natural Hazards
• NS  Near Surface Geophysics
• OS  Ocean Sciences
• PP  Paleoceanography & Paleoclimatology
• SY  Science & Society
• TH  Town Hall
• U  Union Session

INSTAAR authors 

[#] = Number of abstracts per author

• [1] B
• [10] C, EP
• [6] C, EP
• [1] PP
• [1] H
• [3] EP
• [17] B, EP, H, NS
• [2] C, PP
• (alum) [5] GC, H, SY, TH
• [1]
• [2] B, SY
• [1] C
• [1] A
• [2] EP
• [1] H
• [1] OS
• [3] EP
• [2] A, SY
• [2] C, OS
• [7] GC, H, SY
• [1] H
• (alum) [2] PP
• [1] C
• [1] H
• [1] EP
• [4] GC, PP
• [4] H, NS
• [2] GC, SY
• [8] C, GP, PP
• [2] B, C
• [1] H
• [1] U
• + [5] ED, EP, NH
• [1] H
• [1] C
• [2] SY
• [3] C, H
• [6] A
•  [2] C
• [4] A, B, 
• [1] B
• + [4] B, PP
• [10] C, ED, PP
• [6] B, H, 
• [8] A, B, SY
• [1] PP
• [4] A, OS, 
• [9] C, GC, H, U
• [4] C, OS
• [1] B
• + [3] H
• [11] A, B, C, GC, H, NS, SY
• [1] B
• [3] H
• [10] C, ED, EP
• [7] C, H
• [1] H
• [3] H
• + [2] H
• [3] C, EP
• [2] PP
• [4] EP, PP
• + (alum) [13] B, EP, H
• [1] SY
• [14] C, GC, H
• [5] B
• [2] B, C
• [2] C
• (alum) [1] PP
• [1] A
• [3] GC, PP
• [1] C
• [5] B, OS
• [2] B, GC
• [1] B
• [3] A, SY
• [3] B, H, NS
• [2] SY
• [1] C
• [1] B
• [1] SY
• [1] SY
• [10] B, GC, H
• [2] H
• [2] B, NS

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

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