Tropical glaciers are melting fast: Looking for clues to climate change

Tropical glaciers are melting fast: Looking for clues to climate change

Madhurita Goswami, Dec. 18, 2019

Most of us associate glaciers with Antarctica or the northern ice-sheets of the Arctic and Greenland. It may come as a surprise that scientists Alice M. Doughty and Meredith Kelly are studying tropical glaciers at the Rwenzori Mountains of Uganda to improve our understanding of climate change.

The Rwenzori lies only 23 minutes north of the Equator and almost 30 degrees east of the Prime Meridian. There are glaciers here because the life cycle of tropical glaciers isn’t about location but height. Reaching Rwenzori’s glaciers means climbing at least 4,000 meters (more than 13,000 feet) above sea level just to get to the foot of them. Still, in a warming world, height can’t protect these once mammoth ice formations as they rapidly retreat.

Even for Kelly, the term glacier raises images of classic ice masses in the Swiss Alps, which partially melt during the summer and then grow again in the winter due to snowfall.

Meredith Kelly leads expeditions to sample moraines at the Rwenzori glaciers. (Abigail Foerstner)

“Tropical glaciers are really different because summer and winter temperatures are almost the same,” said Kelly, an associate professor of Earth Science at Dartmouth College.

Studies on tropical glaciers have confirmed that they reached their maximum extent around the same time that high-latitude glaciers were at their maximum during the last great ice age some 18,000 years ago. This tells scientists that there was a synchronized warming at the end of the last ice age.

“Tropics are located far from mechanisms of climate change such as summer insolation [exposure to the sun] in northern high latitudes or direct effect of ice-sheets. So, they might be responding to CO2 (carbon dioxide) or other mechanisms we haven’t defined yet,” Kelly said at the 2019 Comer Climate Conference held in southwestern Wisconsin in early October.

CO2 is a greenhouse gas is warming the Earth as it collects in the atmosphere at ever higher levels due to emissions from human use of fossil fuels that include coal, gasoline and natural gas.

Alice Doughty works on glacial models based on data obtained from the Rwenzori glaciers. (Abigail Foerstner)

Kelly proposed that the temperature gradient between the poles and the tropics might have played a role. When the gradient is smaller, there is less outflow of heat from the tropics.

For a long time, scientists puzzled over factors driving changes in tropical glaciers. Initially, they attributed the main cause to precipitation as seasons in the tropics can be divided into wet and dry.

However, “tropical glaciers couldn’t have advanced (during the last glacial maximum) due to precipitation alone. There had to have been substantial cooling at high altitudes,” said Doughty, a visiting assistant professor of geology at Bates College. “We don’t have strong thermal seasons in the tropics. So, these glaciers were/are responding to what’s happening in the tropical atmosphere.”

A vast number of tropical glaciers are in the Andes in South America. Others are on Mt. Kenya in Kenya, Mt. Kilimanjaro in Tanzania and the Rwenzori Mountains in Uganda and the Democratic Republic of Congo. Some are located in Papua, New Guinea.

“It takes a village” – How locals are helping researchers in Uganda

Researchers studying tropical glaciers, which are relatively small, face some unique challenges. Not the least of them is having to hike up mountains with their equipment for days on end. They can’t reach the sites by helicopters or cars. Local guides, who know the mountain trails, become essential to their success.

Moraines (ridges of boulders) left behind by retreating glaciers are used to determine their past extents. However, looking for boulders in the Rwenzori Mountains is like playing a game of hide and seek, said Doughty, who works on glacial modeling. As many as 58 people have to work on finding these boulders in the woods. “It takes a village,” said Doughty.

“It is difficult to find these boulders as they are covered with vegetation, which can be up to a meter thick,” said Kelly, who samples the moraine boulders. In this case, too, locals help to cut down the overgrowth with their machetes.

The mat of vegetation conceals massive gaps between boulders, Doughty said and hinted at the risk of accidents. But walking is the only way to find boulders, which can’t be spotted from space or with drones.

Tropical glaciers on the peaks of the Rwenzori Mountians in Uganda are small and rapidly receding (Meredith Kelly/Alice Doughty)

Doughty, at first, was uncomfortable with the idea of guides and porters, and the dynamics of teaming everyone together. “So, we talked about jobs in the area. In mountain communities, being a porter is a huge part of that and some were raising money to go to college. I realized we were supporting the economy,” she said.

Rwenzori is also the name of a national park managed by a government agency, the Uganda Wildlife Authority, and it also runs the porter service. “We have really benefited from its system, which allows us to find collaborators in Uganda,” Kelly said.

Photo at top: Local guides play an important role in finding boulders left behind by retreating glaciers. (Meredith Kelly)

Glaciers as “global thermometers” show the fast pace of melting in a warming world

Glaciers as “global thermometers” show the fast pace of melting in a warming world

Madhurita Goswami, Dec. 18, 2019

Glaciers across the globe behave in a synchronized manner, said geologist Thomas Lowell at the recent Comer Climate Conference, an annual national conference held in southwestern Wisconsin. Not only does he study glaciers around the world to reach this conclusion but also compared data obtained by separate dating techniques.

Sounding the alarm, as we warm temperatures the glaciers retreat faster, he said. This, in turn, would change the sea levels in coming years by a greater extent than people imagine now, Lowell added.

The results show that incoming solar radiation, which varies seasonally in the two hemispheres, is not the major factor affecting climate change and has implications for identifying other factors.

“I have looked at glaciers from central-northern Greenland to Antarctica,” said Lowell, a professor of geology at the University of Cincinnati. “They were universally behaving in the same way during the last glacial maximum. They were out, bounced around a little bit and receded at the same time.”

The maximum reach of the ice age, or glacial maximum, left its mark on the Earth’s landforms some 18,000 years ago.

Thomas Lowell gives his presentation on comparing data from glaciers around the world (Abigail Foerstner)

Glaciers are “global thermometers” which track temperatures and can be used for reconstruction of our past climate. However, they don’t leave a continuous record. “We get different pieces from different places and try to match them. They might not match because there are some missing pieces,” Lowell said. There is, however, substantial correlation in the data that he is trying to quantify.

The pattern of glacial movement also shows how sensitive they are. Lowell said, “The zigs are around a thousand years apart. It shows, in my opinion, that a temperature pattern was superimposed on the glaciers. It was generally cold but there were warmer and colder times.”

Of the two techniques used to obtain glacial data, radiocarbon dating is the traditional one. It requires accumulation of organic material around the periphery of a retreating glacier. Scientists study the decay of carbon-14 in this organic matter. The other dating technique relies on moraines, a chain of boulders tossed behind by retreating glaciers.

When particles produced by galactic cosmic rays strike the rock surface, beryllium-10, a radioactive isotope of beryllium, is produced. Scientists can analyze beryllium-10 decay to find out when it was generated, which corresponds with moraines losing their ice cover.

“Each technique has its advantages and limitations. Lowell’s emphasis on observing both the chronologies and finding a correlation between them is a more compelling reconstruction of what happened in the past,” said Jerry McManus, a climate scientist and professor at the Lamont-Doherty Earth Observatory of Columbia University.

“In cases where organic matter is available, it is relatively easier to take measurements and more data can be quickly produced. However, the amount of carbon-14 in the earth’s atmosphere changes over time and it is a bit of a moving target,” he said. On the other hand, many glacial sites don’t have moraines and so beryllium-10 dating is not an option there.

Photo at top: Huge icebergs are breaking off the Greenland glaciers. (Gary Comer/Comer Family Foundation)

Climate science pioneer Wallace Broecker memorialized at namesake symposium

Climate science pioneer Wallace Broecker memorialized at namesake symposium

By Zack Fishman, Dec. 18, 2019

The locked office of the late climate scientist Wallace “Wally” Broecker displays a wooden ship’s wheel, mounted on a window-paneled wall behind his former desk. The wheel overlooks the forested campus of Columbia University’s Lamont-Doherty Earth Observatory, where Broecker conducted research for nearly 70 years. It originated from one of LDEO’s first vessels used for ocean chemistry testing in the 1960s, and the choice of its current home is no accident: The captain’s wheel is symbolic of Broecker’s leadership at the institution, says paleoclimatologist and LDEO professor Jerry McManus.

Office with desk, ship's wheel and large window
Wallace Broecker’s former office is on the second floor of the Gary C. Comer Geochemistry Building in Palisades, New York. LDEO administration hopes to re-open its doors for continued use while preserving Broecker’s memory, although it has not yet come to a decision. (Zack Fishman/MEDILL)

Broecker, who died in February at the age of 87, made significant contributions to the scientific understanding of the oceans, climate and climate change during his long academic career, mentoring several generations of students. Born in Oak Park in 1931 as the second of five children, he received his Ph.D. in geology at Columbia and became an assistant professor there in 1959. Since then, he pioneered the use of carbon isotopes and trace compounds to date and map the oceans, as well as introducing the concept of a “global conveyor” that connects the world’s oceans through heat-driven circulation. Broecker also popularized the phrase “global warming” in a 1975 paper and has been deemed the “grandfather of climate science” by many in the field.

More than 200 researchers and family members celebrated his legacy at the Wally Broecker Symposium in late October, with many of the world’s leading earth scientists in attendance. McManus led the organization of the three-day conference, which took place on the LDEO campus, an hour’s drive north of Columbia’s main campus in Manhattan. Dozens of Broecker’s former students and colleagues presented new research based on his findings, as well as heartfelt and entertaining stories about the late scientist.

Princeton geoscientist Michael Bender opened the symposium with a summary of Broecker’s decades-long career, which he said spanned dozens of research topics and many ambitious experiments. Bender said Broecker first visited LDEO for a summer job in a lab and he learned about the new technology of radiocarbon dating, or measuring isotopes of carbon to determine the age of materials. Broecker’s supervisor was impressed enough to arrange the young scientist’s transfer to Columbia from Wheaton College in Wheaton, Illinois, for his senior year and asked the 22-year-old to take over the lab.

An innovative Broecker would go on to use radiocarbon dating in 1958 to measure how glaciers affected the depth of a prehistoric lake in Utah. He also pioneered the use of tracking radioactive particles to study circulation in bodies of water, as he did in the 1980s when he poured radium into lakes in Ontario, Canada — with governmental permission — to follow its motion.

“I tried to look at Wally’s work as a whole, and the scope is just completely overwhelming,” said Bender, one of Broecker’s former students. “We were incredibly lucky to have the opportunity to be associated with this man and his science.”

Wallace Broecker wearing a medal with President Bill Clinton clapping behind him.
President Bill Clinton awards Broecker the National Medal of Science in 1996. He received the award for his research on ocean circulation, the global carbon cycle and climate change. Broecker won several awards in the Earth sciences, including the prestigious Crafoord Prize, the equivalent of the Nobel Prize for his field. (Lamont-Doherty Earth Observatory)

Other researchers from numerous fields credited Broecker’s findings as foundational to their work. Geoscientist Jean Lynch-Stieglitz of the Georgia Institute of Technology said she “found Wally’s fingerprints all over” her research, as she used his model of the ocean “conveyor belt” to track how nutrients and heat circulated in the last 10,000 years. LDEO paleoclimatologist Dorothy Peteet shared the results of her and Broecker’s joint investigation into the causes and timing of glacier retreats during the last ice age.

Presenters also highlighted the scientist’s outspoken views on addressing climate change. Peter Schlosser, an earth scientist at Arizona State University, played a video clip of Broecker’s final address to the scientific community about necessary actions to limit global warming. From his hospital bed in 2018, Broecker said more drastic climate mitigation measures must be considered, such as capturing carbon dioxide from the air or injecting cooling aerosols into the atmosphere. The address was first played at the Planetary Management Symposium, held last year at Arizona State.

“If we are going to prevent the planet from warming up another couple degrees,” Broecker said, “we’re going to have to go to geoengineering.”

Praise of Broecker’s personal character pervaded the symposium with warm testimonies to his values and quirks. He was an “intellectual snow plow” who tackled problems with rigor and confidence, said Princeton geophysicist Daniel Sigman. His passion sometimes overflowed into what LDEO oceanographer Mark Cane called “strategic and effective” tantrums, often digging in his heels against administration and correcting guest speakers in his own class. Broecker was also a lifelong prankster, with stories of his tomfoolery tracing back to high school, when he rarely got caught. More recently, he had a staff member take his place during a video conference and mime the words Broecker was saying off-camera. (He didn’t get away with that one.)

Jerry McManus next to a lectern and giving a speech.
LDEO professor Jerry McManus, who led the organization of the Wally Broecker Symposium, speaks about abrupt climate change that occurred at the end of the last Ice Age. (Zack Fishman/MEDILL)

“He had such a human heart,” McManus said, and fellow LDEO faculty member William Ryan called Broecker a “master of kindness.” Numerous attendees said he was an important influence in determining their career path as someone who often opened doors of opportunity. Ahbijit Sanyal, a director at Johnson & Johnson and another former student, said his teacher was “like a father” to him and once used his influence to help Sanyal’s wife immigrate to the U.S.

Yet more often, Broecker played down his status as a prolific researcher, and one scientist said he didn’t care about “personal wealth” or “glory.” He seemingly disliked his fame for popularizing the phrase “global warming” — he once offered his students $250 to find an example of its use before his landmark 1975 paper, though none were successful.

But Broecker paid a lot of attention to young scientists and their success. Encouragement and affirmation goes a long way for junior scientists, said Mayaan Yehudai, a Ph.D. student at LDEO and previously a teaching assistant for two of Broecker’s classes.

“When you’re a student, you don’t always know when you know that you’re qualified,” Yehudai said. “So, to have somebody like that tell me that I’m qualified or to believe in me is very, very meaningful.”

After the first full day of presentations, the visitors attended a ballroom dinner and listened to several heartfelt speeches from Broecker’s family and friends, including several senior members of LDEO. Filmmaker Anna Keyes presented a video centered around an interview with Broecker, her grandfather. His two younger sisters, Bonnie Chapin and Judy Revekop, told stories of growing up with a high-energy and caring Wally.

Young Wally Broecker posing with his name in mugshot style.
Broecker, then 22, poses for his student ID photograph as he joined the Columbia University geology department in 1953. (Lamont-Doherty Earth Observatory)

Broecker didn’t want a memorial, so the symposium was the largest gathering his family has attended in his memory, Revekop said. Nevertheless, she believes he would have appreciated the event.

“I’m sure he would love to be a little something sitting on a corner, watching and enjoying,” she said.

The dinner also featured an outpouring of musical talent. Geophysicist Richard Alley of Pennsylvania State University wrote and performed a song about his colleague’s career on a prerecorded video, drawing laughs from the attendees. Tom Chapin, a brother-in-law of Broecker and Grammy-winning folk singer, also played an original song about the late scientist’s research. His daughters, Abigail and Lily Chapin, later joined him to sing — this time, less about science and more on spiritual unity.

Broecker’s daughter Cynthia Kennedy, who attended the dinner and livestreamed the seminar, said the symposium was “fabulous” and praised the community of scientists it brought together.

“What they did for him was as much as he gave to them, because that’s what kept him going: their curious minds and their youth and their energy,” Kennedy said. “He fed on that, and that’s what made him who he was.”

Read more about Wally Broecker and his partnership with late philanthropist Gary Comer to launch a national initiative of climate research fellowships that Comer funded. The Comer Family Foundation continues to support the climate change research program. 

Photo at top: Wallace Broecker in 2018 at Leeward Farms in Casper, Wyoming. (Jasmin Shah/Comer Family Foundation)





By Elena Bruess, Oct. 20, 2019
Near the peaks of Mount Everest – towering some 5.6 miles above sea level – the ancient Khumbu Glacier is melting.

Never before in the last 70 years has the massive ice rock melted more quickly than it is retreating now. It is losing thickness at an unprecedented rate – about 131 feet in the last 10 to 15 years, to be exact. And the Nepali communities surrounding the Khumbu are feeling the consequences.

The impact of the depleted glacier could eventually reduce access to freshwater for these areas and could hinder Nepali guides who are dependent on the tourism from Mount Everest.

Rapidly melting glaciers result in floods or, as geoscientist Jeff Severinghaus calls it “a glacial lake outburst flood” – a gradual accumulation of meltwater from a receding glacier which often forms a lake in the space previously occupied by the glacier.

Severinghaus is a professor of geosciences at the Scripps Institution of Oceanography at University of California, San Diego. He has worked extensively with the ice sheet in both Greenland and Antarctica, focusing in ancient climate to better predict where man-made global warming is taking us now. He spent a year and a half in Nepal on a rural development project and continues to understand many of the climate implications experienced in the region.

“The problem is that those lakes are dammed up by ice or mud or a mixture of both. Neither which is very solid,” Severinghaus said, while participating in the Comer Climate Conference in southwestern Wisconsin this fall. “All of sudden the dam bursts after years following the glacial retreat and you get a massive amount of water roaring down these steep mountain valleys at very high speeds. They are extremely violent. People get killed and houses are destroyed.”

Lobuche is a small settlement near the base of Mount Everest that many travelers stop on their way up to the mountain. Dingboche is a small Sherpa village. Both are in Khumbu Glacier region. (Courtesy of Laura Mattas)

Nepali towns near the base of the Mount Everest have long depended on the meltwater from the Khumbu Glacier. Both it and the annual monsoon season give communities in the area the freshwater supply that they need to survive. Now that the glacier is receding, the real question going forward is how much and how fast will the melt occur. Depending on the accelerating pace, the glacial recession can have even more serious implications for the area.

Laura Mattas, a climate science and geochemistry masters candidate at University of Maine, climbed seemingly into the clouds to study the Khumbu Glacier this last summer. She researched the movement of the glacier historically and presented her findings at the Comer Conference. According to Mattas, mountain guides are one of the best jobs in the region. Yet the impact the damage could incur a big economic shakeup for those who depend on the area for this kind of work.

“A lot of the economy of Nepal is based around tourism and what they do there is extremely different than what we know in the US,” Mattas said. ”The porters [mountain guides] are what a lot of the people become and that is an extremely taxing job. So they respond to climate change in knowing how it will impact tourism.”

In adapting to the changing glacier, Nepal might not be centered on climate change mitigation strategies in very rural areas, but there has been some progress in installing flood warning systems. A sensor placed up the mountain will send a signal down a few miles telling communities a flood is on the way and to get to higher ground. According to Severinghaus, this has saved a lot of lives.

Yet, the impact of the Khumbu Glacier melt might be harder to mitigate in the future. It is somewhat unclear how the area will change as the glacier loses more and more volume.

“It’s a little hard to say. It’s true that globe will be getting warmer and warmer so that means there will be more melting,” Severinghaus said. “But eventually, the glaciers are so reduced in volume they won’t even make much in the way of melt.”

Either way, the foremost question for these communities still remains, Mattas said.

“If the glacier is retreating more than it ever has, what does this mean for the area and more importantly, will it be able to rebuild?”

Photo at top: Climate scientist Laura Mattas is tracking past retreat of the Khumbu Glacier in Nepal, which is melting faster now than at any previous time. For many Nepali communities, the increasingly melting glacier has negative consequences. (Courtesy of Laura Mattas)
4,000 floating robots take on climate change

4,000 floating robots take on climate change

By Elena Bruess, Oct. 16, 2019 –
I ziplined recently with a scientist who told me that her work involved almost 4,000 floating robots and a massive global computer database that could help her predict the future of our world’s climate.

This was during a break in the Comer Climate Conference and the woods behind conference headquarters held many mysteries, including a zipline and now – for me – the world’s most interesting researcher. I quickly scribbled “should probably catch up with her” in a notebook.

I did. She gave a presentation on her work the next day to climate scientists from across the nation gathered at the annual science meetup in southwestern Wisconsin.

My fellow zipliner is Becki Beadling, a Ph.D. Candidate in geosciences at the University of Arizona at Tuscon. Her work involves climate model simulations and in-field observations specifically focusing on climate change in relation to carbon uptake in the Southern Ocean.

A climate model replicates interactions between important factors that drive the climate, such as temperature, salinity, pressure as well as carbon cycling. The climate model database is called the Coupled Model Intercomparison Project – CMIP for short. The project goes hand-in-hand with the U.N.’s recent climate change reports, generating data from modeling centers all over the world. All the centers are running the exact same experiments and all the data is available through this database for anyone involved.

It’s a big system.

Unfortunately the models can be off the mark.

“The only way we can trust these models is by verifying them against past observations, historical observations and what’s happening now. I want to know how well these models represent these properties,” Beadling said, during another conference break. “And then looking into the future, how well the circulations and properties in this region are projected to change.”

According to Beadling, the models give us a range of possible scenarios of what might happen as the planet warms, glaciers melt, sea levels swamp coastlines and drought threatens millions. The comparison between what the computer analyzes and the actual observations can offer climate researchers a better idea of what to expect in the future. The closer the current observation is to the model, the more accurate the model can be to predict the pace and range of future change.

Geoscientist Becki Beadling, 29, abroad a US GO-SHIP on course from Syndey, Australia, to Papeete, Tahiti, in 2017. During her trip, the team released a number of SOCCOM “robot” floats to observe elements in the water. (Courtesy of Rebecca Beadling)

Observing the elements in the oceans can be a time-consuming and expensive task, though. A couple of years ago, Beadling went on a cruise. This was not your average trip to the Bahamas, but rather a research ship that is meant to measure the properties in the ocean. The same as the models: temperature, salinity, dissolved oxygen, nitrate, etc. The researchers release robot floaters called SOCCOM Floats at the same transects of the ocean decade after decade.

Each floater spends 10 days dipping down and back up, beaming data to the researchers on the land and then the cycle continues again.

The chart above depicts how a “robot” float works. SOCCOM floats work in the same way, but check for more than just temperature, salinity and pressure (Courtesy of Argo)
CAD drawing of a SOCCOM biogeochemical robot float. (Rick Rupan, University of Washington)

“It’s very new. Humans could not look at the great abyss of the global ocean, 71% of the Earth’s surface, because we could only go where we go in a ship,” said Joellen Russell, a biogeochemical dynamics professor at the University of Arizona and the chair of Integrative Science. Similar to Beadling, she works with the global database. She also attended the conference. “Now the robots do our work for us, and they keep working day-in and day-out, it doesn’t matter.”

According to Russell, there are just under 4,000 robots floating around right now, as Beadling mentioned.

Every dot on the map represents a “robot” float in the ocean as of October 11. (Courtesy of Becki Beadling)

When consulting the mix of the robot data and the current CMIP simulations, Beadling, Russell and other climate researchers can attempt to predict what our oceans will look like in the next century. Specifically they look to the Southern Ocean.

“When we think about modern climate, roughly 90% of the excess heat that’s trapped on our planet from greenhouse gas emissions has gone into our oceans. And the Southern Ocean is taking up the most,” Beadling said. “Heat and carbon are the most important components when thinking of the past, present and future of climate.”

The additional heat is in large part generated by human-driven emissions from fossil fuels, emissions that create the greenhouse gas carbon dioxide. CO2 holds heat in the atmosphere and is considered the thermostat of climate change. Even with ocean uptake, CO2 levels in the atmosphere have increased by more than 35 percent to more than 400 parts per million since the beginning of the Industrial Age.

According to Beadling, if we can better understand what those climate changes are going to be and how our oceans are going to react to all this warming, then we can have better projections of what we are facing from climate change and how to better prepare. Right now, the ocean is doing us a favor taking in all this carbon. But the question is for how long will it be able to do so and how fast might the Earth warm once ocean uptake of carbon slows or halts all together?

Looking ahead, a lot is uncertain for climate researchers such as Beadling. But, considering the work being done here, a big global database with a few thousand floating robots could eventually do the trick.

Photo at top: Beadling and colleagues prepare to toss the SOCCOM “robot” float in the ocean. The float will be collecting information for around 7 years. (Courtesy of Becki Beadling)
Khumbu Glacier in Nepal offers clues to rapid retreat of ice

Khumbu Glacier in Nepal offers clues to rapid retreat of ice

By Anne Snabes, Dec. 19, 2019 –

The Khumbu Glacier in the Himalayas retreated rapidly in the past, offering clues to how the glacier will behave in the future, University of Maine research suggests.

Laura Mattas, a master’s student at the university, conducted field research this summer on the Khumbu Glacier in Nepal. She presented her research this fall at the Comer Climate Conference, an annual meeting in Wisconsin of climate scientists from across the country.

According to the National Snow & Ice Data Center, glaciers globally are retreating at “unprecedented rates.” A glacier can retreat by shortening in length or by thinning. In the Khumbu Valley, Mattas and her colleagues found moraines, which are rock and other sediment that were inside, on top of or below a glacier and that were altered by the glacier. The location of the moraines indicated that the glacier retreated quickly at some point since the last ice age. Mattas said that the glacier is able to undergo a “large and rapid change,” which means that it may also change rapidly in the future.

“If that’s the case, that’s a lot of meltwater that’s flowing down valley,,” she said. “Who knows if there’s the infrastructure to deal with” the surge.

Laura Mattas, a master’s student at the University of Maine, is following the retreat of the Khumbu Glacier. (Anne Snabes/MEDILL)

Mattas and other researchers collected 77 samples of rock from the valley, which can demonstrate how the glacier has behaved from the last ice age to today.

“That could predict what the future warming of this area looks like,” she said, “because if it’s known to go fast and just give all that meltwater, then it could be predicting that this glacier is … going through an irreversible retreat.”

Mattas said she and the research group found moraines at a village called Dingboche and at a nearby settlement called Lobuche. A scientist previously found that the moraines in Dingboche were formed during the last ice age. The moraines at Lobuche, on the other hand, are more modern, but Mattas still has to determine their exact date.

The scientists did not see any moraines between Dingboche and Lobuche.

“As we walked from Dingboche to Lobuche, there was absolutely nothing,” Mattas said.

The lack of moraines between the two locations suggests that the glacier melted quickly. If the glacier had retreated more gradually, it would have formed moraines about every few thousand years, so the terrain would show several lines of moraines in the space between Dingboche and Lobuche.

Mattas said a glacier has to sit in one place long enough to form moraines. But in this case, the glacier moved too quickly.

Mattas’ conclusion that the Khumbu Glacier retreated quickly is a preliminary field observation, but it still needs to be supported by data. The samples of rock that Mattas and her colleagues collected may provide the evidence needed to back her claim. They retrieved the rock by drilling holes in boulders. The scientists will employ a technique called Beryllium-10 dating, which can tell them the age of the moraines. This age gives researchers an approximation of when the glacier retreated, according to Mattas.

The research team sits by moraines that were formed by the Khumbu Glacier. The research trip was part of National Geographic and Rolex’s Perpetual Planet Extreme Exhibition: Everest. Photo courtesy of Laura Mattas.

Sidney Hemming, a professor of earth and environmental sciences at Columbia University, said she agrees that in order to accommodate the researchers’ observations, there had to be a “really quick retreat.” Hemming said that it does not really matter what the ages of the two moraine belts are.

“The fact that there’s this big space in between them with no moraines in there means that there had to be a rapid retreat, right?” she explained.

Mattas said she and other researchers are currently studying the past so they can learn what the Khumbu Glacier is capable of doing in the future.

“We’re trying to see how it reacted in the past,” she said, “and from that data, we hope to then use a predictive model to see if that is possible in what we’re seeing today.”

Photo at top: The Khumbu Glacier retreated rapidly at some point between the last ice age and today, and Laura Mattas is trying to determine the exact date of the retreat. She and her colleagues conducted research in the Khumbu Valley as a part of National Geographic and Rolex’s Perpetual Planet Extreme Exhibition: Everest. Photo courtesy of Laura Mattas.

Tiny shells reveal clues to ocean health in North Pacific

Tiny shells reveal clues to ocean health in North Pacific

By Anne Snabes, Dec. 19, 2019 –

Calcium carbonate, a primary ingredient in the shells of tiny marine organisms, reduces the acidification of our world’s oceans.

The ocean is approximately 30% more acidic than when the Industrial Revolution began, and carbon dioxide emissions from human use of fossil fuels have greatly contributed to this increase.

When microscopic organisms called zooplankton and phytoplankton die, they sink to the bottom of the ocean, and their calcium carbonate shells dissolve. This process makes the ocean less acidic. But new research suggests that scientists don’t fully understand how calcium carbonate dissolves in the ocean.

This ostracod, which is a kind of zooplankton, has a calcium carbonate shell. (Wikimedia Commons/ Anna Syme)

Kassandra Costa, a postdoctoral scholar at Woods Hole Oceanographic Institution in Massachusetts  found that calcium carbonate dissolves at a shallower sea floor depth in the North Pacific Ocean than scientists predicted. She presented her research this October at the Comer Climate Conference, an annual meeting of climate scientists in Southwest Wisconsin. Costa told the Medill News Service that there could be a problem with how scientists predict the depth at which calcium carbonate dissolves.

Kassandra Costa talks about clues to climate change revealed in tiny shells at the Comer Climate Conference in October. (Abigail Foerstner/MEDILL)

Costa said that when carbon dioxide enters the ocean, it reacts with water and carbonate ions to produce bicarbonate. When calcium carbonate dissolves in water, carbonate ions are produced. This process replenishes the carbonate ions that were used up by carbon dioxide when it entered the ocean.

Costa said carbonate ions pick up some of the protons (positive particles in atoms) in the water, which makes the water less acidic. Because calcium carbonate is a source of the carbonate ion, it reduces ocean acidification.

Calcium carbonate dissolution makes the ocean less acidic. (Photo: Flickr/Joe Lin. Text in graphic/Anne Snabes)

“When calcium carbonate dissolves in the ocean, as she mentioned, that essentially buffers the acidity that is added by CO2,” said Jerry McManus, a geochemistry professor at Columbia University.

Costa said scientists predicted that calcium carbonate can be found at the bottom of the North Pacific up to depths of 4,400 meters (14,432 feet). This prediction was made using chemistry measurements and theory. Through research, Costa and her colleagues discovered that calcium carbonate can in fact only be found up to depths of about 3,000 meters (9,840 feet) some two-thirds of the predicted value.

Costa sailed in 2014 with other researchers 500 km ( about 311 miles) off the coast of Oregon to the Juan de Fuca Ridge, where she collected sediment from the ocean floor by using a device called a multi-core. She said the researchers gently lower the device to the bottom of the ocean. It punches a hole in the sediment to extract a core of it. Then the researchers bring the instrument and the core back to the boat. The sediment in the multi-core contains clay as well as calcium carbonate from dead zooplankton and phytoplankton.

These tiny organisms are at the bottom of the ocean food chain, feeding other marine species.

Calcium carbonate dissolves in a gradient in the North Pacific. At a depth of 2,300 m (7,544 feet) the sediment at the ocean floor is 60% calcium carbonate and 40% clays. At a 3,000 m sea floor depth, the sediment is only 10% calcium carbonate, as most of the material has dissolved. This means that there is little calcium carbonate in the North Pacific at depths below 3,000 m.

McManus, who also went on the research trip, said Costa’s observation points to the limitation of “broad-brush theoretical constructions.” Costa made actual measurements, instead of solely relying on theory.

Costa said the mismatch between the expected and observed depths suggests that something is missing in our understanding of calcium carbonate dissolution in the sea.

“There’s something extra about the calcium carbonate in the North Pacific that makes it, in actuality, dissolve at much shallower depths than we expected,” she said.

Costa told her audience at the Comer Conference that scientists have already observed calcium carbonate dissolving on the sea floor due to human activity that produces CO2.

Because calcium carbonate is dissolving at shallower depths than predicted, there may be a slightly lower amount of calcium carbonate in the North Pacific than expected. This would mean that calcium carbonate could not compensate for as much carbon dioxide as scientists expected, but more research needs to be done.

Costa said it will take thousands of years for calcium carbonate in the ocean to run out.

“Once that buffer does run out, the acidification of the ocean will proceed much more rapidly,” she explained.

Photo at top: Dan Armhein, Costa and Deborah Leopo work with a sediment core that was collected during a 2017 trip to the North Atlantic. (Courtesy of Kassandra Costa)

‘Grandfather of climate science’ Wally Broecker remembered at climate conference

‘Grandfather of climate science’ Wally Broecker remembered at climate conference

By Zack Fishman, Nov. 20, 2019 —

Dozens of scientists convene every year  at the Comer Climate Conference to share new research about rising oceans and melting glaciers, both today and in the past. The event, funded by the family of late billionaire philanthropist Gary Comer, has been organized since 2004 by famed climate scientists Wallace Broecker, Richard Alley and George Denton.

But this fall, the conference was overcast by Broecker’s death in February. Colleagues, students and friends shared stories and memories of the influential scientist, who passed away at the age of 87 still actively engaged in climate research. The 2019 conference honored his legacy with the latest findings in global climate science.

Born in 1931 in the Chicago suburb of Oak Park, Wallace Smith Broecker — known as Wally to all who knew him — completed his Ph.D. in geology at Columbia University and joined the faculty the following year. As a professor at Columbia’s Lamont-Doherty Earth Observatory, Broecker significantly contributed to several fields of ocean- and climate-related research. He introduced the concept of a “conveyor belt” that connects the world’s oceans through heat-driven circulation and he led the scientific community in using radioactive isotopes of carbon to date the oceans’ past.

Broecker is most well known for popularizing the phrase “global warming” in a 1975 paper that predicted the modern rise of global temperatures. He was also a longtime proponent of action on climate change, warning about the “climate beast” created by CO₂ emissions.

“It’s got the seeds of really terrible chaos on the planet, and we’ve got to start to respect that,” Broecker said at the 2018 Comer Climate Conference.

In his last conference appearance, he promoted controversial measures to mitigate the warming climate such as removing CO₂ and spraying cooling sulfates into the atmosphere.

Wally Broecker speaks to another scientist
Wally Broecker walks through an explanation during the 2018 Comer Climate Conference (Jasmin Shah/Comer Family Foundation)

One year later, several attendees invoked Broecker’s memory in both social and academic settings over the four-day-long conference. They described him as an innovative researcher, supportive mentor and notorious prankster. Broecker once left his research group behind with nothing but water bottles and a note saying they had to walk several miles back to town — only to be waiting with a bus a mile down the road, according to geoscientist Jeffrey Severinghaus,.

Severinghaus, who teaches at the University of California San Diego, earned his Ph.D. at LDEO with Broecker as his academic advisor. He praised the late scientist’s mentorship and academic prowess.

“He had a great talent in seeing the major part of a scientific story and not getting all lost in the weeds,” Severinghaus said.

Jerry McManus, a geochemistry professor at LDEO, attended Columbia as an undergraduate student and took an advanced course taught by Broecker.

“He took the two undergraduates in his Ph.D. class and sat down with us every week and said, ‘Did you follow everything? What did you think about this or that?’” McManus said.

“He didn’t have to do that — he’s in one of the most famous scientists on earth, and you’re just two random students,” McManus continued. “But he took that interest, and it was my observation then as an undergraduate student that he was very generous with me.”

Broecker’s involvement with Gary Comer, founder of clothing company Lands’ End, began after Comer’s yacht trip through the Arctic in 2001. He sailed through the typically frozen Northwest Passage connecting the Pacific and Atlantic oceans and became concerned about the melting ice. He met with Broecker and other scientists to learn about global warming, said Stephanie Comer, his daughter and the president of the Comer Family Foundation.

“This sparked a friendship and the climate change program our foundation supports today,” Stephanie said.

After the meeting, Comer funded dozens of climate research fellowships and later created the conference in 2004 for recipients to share their research. Gary Comer passed away in 2006, but the Comer Family Foundation continues to support the climate change research. Broecker attended every conference until his death.

“Wally was instrumental in shaping the topics and helping to guide the discussions (at the conference),” Stephanie said. “His knowledge was vast and specific and arcane. … While he challenged his students, he was a devoted mentor and celebrated new and diverse generations of scientists.”

(Full disclosure: Zack Fishman receives a scholarship for environmental journalism from the Comer Family Foundation as a student at Northwestern University.)

Elena Bruess and Anne Snabes contributed reporting to this story.

Greenland ‘ice tongue’ at risk of melting away — again

Greenland ‘ice tongue’ at risk of melting away — again

By Zack Fishman, Nov. 12, 2019 —

A 30-mile-long strip of sea ice in northwest Greenland, once thought to be a permanent structure, didn’t exist until 2,000 years ago, according to newly published research from researchers at Oregon State University. The findings suggest that some of the Arctic may melt more quickly in today’s warming climate than previously expected.

The sea ice, known as the Petermann ice tongue, stretches across a narrow valley where the large Petermann Glacier meets the Arctic Ocean. The ice tongue captured media attention in 2010 and 2012 when enormous icebergs, each many times larger than Manhattan Island, broke off into the ocean. New fractures spotted this year threaten to shrink the ice tongue to its smallest size in modern history.

Renowned geoscientist talks climate research, renewable solutions

Renowned geoscientist talks climate research, renewable solutions

By Zack Fishman, Oct. 29, 2019

Richard Alley caught a cold while flying to southwest Wisconsin for the annual Comer Climate Conference land, hosted each fall by the Comer Family Foundation. But the illness didn’t stop the seasoned scientist from celebrating each research presentation with emphatic words of encouragement, and he used his closing speech to remind his peers of their crucial role in combating climate change.

As a professor of geosciences at Pennsylvania State University, Alley has spent over three decades studying glaciers around the globe. When not in the lab, he has testified in Congress three times and hosted the PBS documentary series “Earth: The Operators’ Manual,” in which he explained the science of climate change and introduced technological solutions to the problem.

Alley joined journalists reporting for the Medill News Service in the library of late billionaire, Lands’ End founder and yachtsman Gary Comer. Surrounded by books on sailing and the Arctic, Alley answered questions about climate change. This interview has been edited for clarity and brevity.

Why do you think it’s important to bring glaciologists, oceanographers and other scientists together for this conference?

This conference brings this amazing range of people working on modern atmospheres, modern oceans, modern ice and rocks, and the history of all of these. I believe that there’s a cross-fertilization — that the skills, the knowledge, the modeling tools that are developed in one of these fields inform the others.

What inspired you to work on climate issues?

I was greatly interested in geology, collecting rocks, crawling through caves and going to national parks. I just liked those growing up. So, I majored in geology and went to Ohio State. I desperately needed a summer job, and there were two summer jobs open. One of them was cleaning fossils with a dental pick, and I’d probably be an evolutionary biologist now, but the other one was helping the glaciologist. So I started working on ice, and once you get very far into ice, you realize it has this glorious climate record in it, and you realize it’s melting, and now you’re a climate scientist.

Why has science communication and helping others understand climate change been important to you?

Because really, it’s our job. I am not a meteorologist, but I know some of them, and there’s been a fascinating evolution in how meteorologists view their job. They got to the point that they were able to forecast the weather well, and they realized that when they forecast a disaster or possible disaster, many people were not responding to it. And they realized that they weren’t communicating in a way that conveyed all the information that the public needed to make use of the information. They looked at themselves and said, “Our job is not understanding the weather, our job is not forecasting the weather — that’s part of the job. Our job is to make it useful to the people who pay for it.”

So, I’ve been inspired by what they’ve done and seeing what other people do in the communications realm because there’s very clearly a huge disconnect between what we know about climate, about energy, about our future and what is being done with that knowledge. Ultimately, I really do believe that the public has paid partially for my education, partially for my job, and that I owe it to them to make the information useful as well as to get the information.

How have you, Gary Comer and Wally Broecker (late geophysicist and co-founder of the Comer Climate Conference) contributed to science communication?

Gary had a vision worked out with Wally Broecker and others of using the history of climate change to inform good decision-making. This was partially because he really wanted to make a difference with his money, and he was looking for those topics that were not well covered.

So by gaining information on this topic, which is so miscommunicated, this immediately drops us in the communications. How do we do this? How do we learn? If I ever fall into scientific jargon, it probably won’t work.

You’ve been very optimistic in the past about the economic opportunities of solving climate change. How do you feel about it now?

I still believe that if we use our knowledge, we’re better off. Lazard, the world’s largest independent investment bank, puts out statements on what different forms of energy costs to add to our electric grid in the U.S. They have said that if you got rid of all the subsidies for wind and sun, but you left in place all the subsidies for fossil fuels, that in many places and many times now in the U.S., wind and sun are still cheaper.

We’re the first generation in all of history that knows that we can build a sustainable energy system if we want to, and that knows that right now, if you actually got rid of those subsidies for fossil fuels, that renewables are really cheaper.

This interview has been edited and condensed.

Photo at top: Richard Alley speaks to an audience of more than 50 ocean and climate scientists at the Comer Climate Conference. (Abigail Foerstner/MEDILL)

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