Crystal Rao, a geoscience graduate student at Princeton University, bases her research on the environmental changes and climate impacts on the species in clues from nitrogen isotopes in fossils.
Rao uses the ratio of two common forms of nitrogen as a standard, and compares it with the nitrogen inside the tooth of the megalodon shark. She has reconstructed a picture of when and where megalodon sharks topped the food chain in Arctic waters. Rao said this fierce predator could “basically eat anything in the ocean”.
Yet this 50-foot long shark, went extinct some 3.5 million years ago. Rao said the food source the sharks relied on to fuel their massive bodies caused their downfall.
“As climate shifts, maybe the production in the ocean could change,” Rao said. “And depending on what the ecosystem responded to, there could be less food availability” for marine life today just as those causing the demise of the megalodon sharks.
And that’s where the nitrogen fingerprint in the teeth comes in. The nitrogen isotope levels change in warm spells compared to ice ages so that Rao can track climate change in the distant past. Nitrogen isotopes from the Atlantic and Pacific Oceans mix during warm spells but ice ages lower sea levels, cutting off Atlantic from Pacific waters and and leaving a distinct isotope in each ocean. ,
Rao shared her research at the Comer Climate Conference this fall, an annual gathering of global climate scientists held virtually for the third year due to COVID-19. Comer conference veteran climate scientists, graduate students and post-docs investigate the effect of climate change from ancient life forms to theoretical models.
While Rao’s work examines a species belonging to an ancient era, another Comer scientist’s work takes estimations of the possibilities for the future.
Edmund Derby, a climate science Ph.D. student at Oxford University, utilizes simple models of Arctic sea ice from his past research in 2009 to examine the bifurcation or tipping point accompanying ice cover changes throughout the season.
Derby’s research presents climate from basic principles to its core behavior. In the scientific model, when atmospheric carbon dioxide exceeds a certain point, after all the Arctic ice melts, it is no longer possible to gain back the ice. His research presented at the conference investigates this tipping point under a model when the Arctic is covered in ice all year round.
“When you’ve reached this tipping point, you don’t get a reversible change once you’ve lost your ice cover,” Derby said.
The temperature of the Arctic is intrinsically connected with global warming across the rest of the world. In a phenomenon known as Arctic Amplification where the Arctic warms twice as fast as the rest of the world, which has warmed in excess of 1 degree Celsius (1.8 degrees F) with global warming due to emissions from human reliance on petroleum-based fuels.
The ice has the light reflective property that redirect the heat. But as it melts, the heat-absorbent ocean water takes its place, according to Derby.
With heat transport to lower latitudes, as the Arctic warms up, the transfer of heat to the Arctic would be expected to decrease.
However, in a changing climate, the transport of water vapor or clouds into the Arctic can counteract the cooling of the heat transport. The water vapor causes local temperature in the Arctic to rise.
In his research, Derby is adding more factors into the model to make it more realistic to the Arctic ice cover, and to investigate how the global rise of greenhouse gas will impact the ice melt at a local level.
Rao said, in her field of geoscience, the past informs the present and the future. Studying the ancient past of Earth’s environment builds a better understanding of the complex systems involved.
“Only when we can really understand or estimate the future better, then we can come up with better plans in terms of how we do climate adaptation and climate mitigation,” Rao said.
The numbers of climate change may seem small, but a small change now may mean a colossal shift into the future. <The changes are occurring now – we don’t want to suggest this is a problem for the next millennium.
Through Rao and Derby’s research of both the past and the future, concerns of climate change continue to loom in both the vanishing fabric of the Arctic and the demise of a species.
Photo at top: Arctic water and the atmosphere help scientists reconstruct the past climate record and inform models for the future. (Photo by Kai Boggild, distributed via imaggeo.egu.eu.)
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].”
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’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.
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.
“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.
What do Antarctic climate scientists and Nordic Vikings have in common?
More than you’d think.
After being cast out of Iceland for murdering his neighbor, Erik the Red, the notorious Viking who walked the Earth around 985 A.D., braved the unforgiving seas in search of a new home. That’s according to Christopher Klein’s History article “The Viking Explorer Who Beat Columbus to America.” Wrapped in layers of pelts, tools in hand, the Viking dropped anchor on new land. Gradually, he took control, founding the first European settlement in what is today Greenland.
An alpine forest turns into a desert within a mere 16,000 years – the geologic equivalent of a blink of an eye. The transformation is just one climate mystery waiting to be solved.
Wondering what drives local rainfall? Curious about tipping points for the entire global weather system? To find answers, you’ll have to go through the “lake mafia,” a disparate collection of scientists who study closed lake basins.
They admit they don’t have definitive explanations. But with the clues they collectively gather and assess, they’re are coming ever closer.
That’s why such a “mafia” even exists, or was jocularly referenced by Douglas Boyle, a climatologist at the University of Nevada, Reno, who identified his colleagues with that specific moniker during a presentation at the 2018 Comer Climate Conference this fall on climate in the Mono Lake basin.
The mafia members gathered at the annual conference to present their latest research findings. Yonaton Goldsmith, a geochemistry postdoc at the California Institute of Technology, studies lakes in China. Geochemist Sidney Hemming and her sixth-year Ph.D. student Guleed Ali with Columbia University’s Lamont-Doherty Earth Observatory, pursue fieldwork at Mono Lake in California. Adam Hudson, a geologist with the U.S. Geological Survey, studies the now nearly empty basin of ancient Lake Chewaucan in Oregon.
Lakes that don’t have an outlet are called closed basin lakes. These provide vital clues to understanding and developing theories of climate, Goldsmith said. “There are abrupt events where lakes rose rapidly and we would like to know the relationship of these events to climate changes,” Goldsmith says. “Why does this happen? How does it happen? This is still an enigma but we do really see these rapid changes in lake size and ultimately rainfall.” The big picture goal, Goldsmith says, is understanding the mechanisms of climate and how rainfall water availability respond to climate changes.
In the United States, the Great Basin watershed, an arid area that extends from California to Utah, is a hotbed of study for paleoclimatology – the study of climate past stretching back hundreds of thousands and even millions of years. These scientists are telling the story of how lake changes that occurred naturally inform our most pressing concerns about the pace and magnitude of climate change as human use of fossil fuels are pushing it now. But the history of these lake scientists, their relationships to each other, and their work tells a story as well about how science is conducted and how powerful hypotheses are developed over time.
“The lake scientists at this conference come from different institutions and we work in different places around the globe,” Goldsmith says. “Before this conference we weren’t really connected, it wasn’t an organic connection … and I think that for us this whole becoming a gang has happened here [at the Comer Conference]. Oh, we’re all doing the same thing! We’re all working on really similar questions! We should be talking to each other.”
Columbia University geochemist Wallace Broecker is the common thread among these lake researchers. They are his former students, students of his former students, or of past and present colleagues. His decades of research span oceanography and climate science. He is credited with discovering the global circulatory system of the Earth’s ocean and was a pioneer in radiocarbon dating. Broecker began investigating the geology of Pyramid Lake in Nevada over 60 years ago, when he was pulled aside by Phil Orr, a pipe-smoking scientist in cowboy boots who told him, “Look kid, I can tell you know a lot about math and science. But you don’t know a goldarn thing about the Earth. You come with me for three weeks and I’ll change your life.”
Pyramid Lake is where Broecker collected his first sample of lake limestone, towers of rock called tufas that jut out from the shoreline. “It was a tufa from the highest shore line of [ancient] Lake Lahontan,” Broecker explains. “So I got interested in those lakes. And dated quite a few samples and then had students that worked on it, and then more recently these other people appeared who, you know, are eager to work on it, so they created the ‘mafia’ … they were following in my footsteps in a way.”
Broecker’s work analyzing tufas and recording the history of Pyramid Lake and others as they expanded or receded helped develop current theories of how temperature, rainfall and evaporation are connected, and how quickly they respond to changes. If lakes can dry up in a matter of centuries, than our current pace of global warming can have a profound impact on local climates, threatening future water availability.
“Most precipitation that comes to the Great Basin falls as snow in the winter,” Hudson explains. “And it comes from the Pacific Ocean, and where it comes into the coast and how often it gets there is controlled by a variety of things.”
At the Comer Conference, the mafia presented new research on lake regions. Ali demonstrated Mono Lake’s historic fluctuations with new research. Hudson used ancient fossilized fish remains to map a more precise history of Lake Chewaucan’s past volume. And Goldsmith linked lakes in East Asia to water availability. “With geology, what’s going on today informs how we think about what see from the past record,” Hemming says. “I feel like I’ve done a second Ph.D. working on Mono Basin.”
Another equally important reason that scientists are drawn to these lakes and to the flowing ice of glaciers is because of their intrinsic and captivating beauty. Hudson Tufas in Mono Lakedescribes a section of mountain, a fault between two lava flows in Southeast Oregon, as “the walls of Mordor”; Hemming has been coming to Lake Mono for years.
“It’s really the only lake I ever studied,” Hemming says. “Every day is a discovery it is so beautiful and enigmatic and I’ve never not spent a single day that I went out in the field that I didn’t come back thinking: I really learned or discovered something that I hadn’t known before. It’s just that … field work in general just brings that level of discovery to your life. It’s way better than the lab.”
Photo at top: Geo-chemist Yonaton Goldsmith digs through lake sediments in Mongolia. (Courtesy of Yonaton Goldsmith/Caltech)
By Austin Keating,Video by Tiffany Chen and Austin Keating, Nov. 22, 2017 –
Scientists take to the field to study rapid warming and cooling events in Earth’s past. They find clues in ice and rock, lakes and sediment across the globe. Rebuilding climate change patterns from the past enhances predictions for the future as human use of fossil fuels accelerates global warming.
Leading geologists and climate researchers shared their latest discoveries and new developments at the Comer Abrupt Climate Change Conference in southwestern Wisconsin this fall.
The Comer Family Foundation has supported climate science researchers for 15 years now. This year, scientists presented a wide array of new discoveries, such as looking at how heavy rainfall in California over the past year and years of drought prior to that are depleting snowpack that streams water into the region.
Researchers also presented new data on glacial melt in Greenland, as well as melt in the Bhutan region of the Himalayas, where the lower-elevation faces of glaciers are thinning as much as 10 feet per year, according to research presented at the conference by Joerg Schaefer of Columbia University’s Lamont-Doherty Earth Observatory. Sea level rise as Greeenland glaciers melt and strained freshwater resources for several countries due to thinning Himilayan glaciers pose major concerns.
PHOTO AT TOP: A visualization of aerosols in the atmosphere above China recorded by satellites in 2006. Human-sourced aerosols and other greenhouse gases coming from China are rising, and scientists at the Comer Conference advocated for policy action to curb the trend (Courtesy of NASA).
NOTE: Tiffany Chen and Austin Keating are Comer Scholars, a Medill scholarship program supported by the Comer Family Foundation to promote graduate studies in Science and Environmental Journalism.
Climate change is an urgent threat linked to floods, drought and increasing heat waves. While carbon dioxide emissions continue to rise, President Donald Trump pulled the United States out of the Paris Climate Accord meant to cap emissions and the temperature rise due to them. Scientists gathered at the Comer Climate Change Conference in southwestern Wisconsin this fall to share their latest research and emphasize the critical need to fight climate change now.
Scientists agree that cutting back carbon dioxide emissions from fossil fuels and the investment in renewable energies might provide a solution. We have many alternative technologies already.
But one country can’t fight climate change on its own, it requires collaborations and communication among nations, scientist, law makers and the public.
PHOTO AT TOP: Climate change scientists gathered at the Comer Abrupt Climate Change Conference this fall to share their latest research and their deep concerns for the future ahead. (Tiffany Chen/MEDILL)
NOTE: Tiffany Chen is a Comer Scholar, a Medill Scholarship program supported by the Comer Family Foundation to promote graduate studies in science and environmental journalism
Methane, a greenhouse gas frozen by the megatons in Earth’s melting ice, holds the potential to dramatically turn up the thermostat for the planet. But new research shows that a bacterial hero from Earth’s soils and seas will keep the thawing gas at bay.
Methane-eating soil microbes will prevent large plumes of methane from reaching the atmosphere as frozen deposits of it begin to thaw due to climate change, according to a paper in Nature recently published by Vasilii Petrenko and Jeffrey Severinghaus of the Scripps Institution of Oceanography at the University of California, San Diego. While Severinghaus doesn’t study microbes directly, he’s able to show their effect on past climates by going to Antarctica and sampling ancient air, he told colleagues during a presentation at the Comer Abrupt Climate Change Conference in southwestern Wisconsin this fall.
Scientists previously thought thawing methane deposits may have caused an abrupt 50 percent rise in atmospheric methane concentration during a rapid warming period at the end of the Younger Dryas, a cold period that ended 11,600 years ago. The prospect raised alarms for a potentially devastating climate feedback from methane, which molecule for molecule, traps at least 25-times more heat in the atmosphere than carbon dioxide.
Through 10 years of sampling ancient air, Severinghaus, his graduate students and the rest of his team were able to show, however, that during the warming period, no detectable methane in the atmosphere came from thawed deposits.
They demonstrated this by looking at the radiocarbon content of 11,600-year-old Antarctic ice, exhuming a ton for each measurement at a precise and narrow vein of ancient ice originally deposited by snowfall on Younger Dryas glaciers. They gathered a corresponding control of modern-day air cleared of carbon-14 for each measurement as well.
Methane released from thawed deposits has no carbon-14, because it’s old and the radiocarbon content decayed long ago. But methane released from natural sources such as wetlands is fresh, and has detectable carbon-14. Carbon-14 builds up in the air and in all living organic things as cosmic rays bombard atoms in the atmosphere.
“If that 50 percent increase in methane concentration was actually caused by the tundra getting warm and burping out all of this methane, then the concentration of carbon-14 relative to the more abundant carbon-12 should have gone down by 30 percent,” Severinghaus said. “We should really see a huge signal if this idea is correct …and we don’t.”
He added that methane-consuming soil microbes at the time must have stopped most of the thawing methane from reaching the atmosphere—just as their oceanic cousins did when they ate 99.9 percent of the methane released during the Deepwater Horizon oil spill in 2010.
Wetlands, which belch methane when it rains, and other natural sources were the main culprits for the rise in methane during the Younger Dryas warming period, Severinghaus said.
“If it didn’t happen back then, it won’t happen now and it won’t happen in the future,” Severinghaus said. “We can focus our attention back on CO2 [carbon dioxide], which really is the problem, and not worry so much about methane. So check one thing off the list.”
Pennsylvania State Geology Professor Richard Alley concluded Severinghaus’s presentation by applauding the amount of work that went into the research.
“Jeff could stand up here and give five or six more talks that have come out of these samples, it’s just really spectacular,” Alley added.
PHOTO AT TOP: Vasilii Petrenko works in the Severinghaus lab, and went to Antarctica to measure radiocarbon in ancient glacial ice. This chamber melts the ice so he can capture and measure the methane content, as the ice traps air bubbles of the atmosphere as it existed 11,600 years ago during a rapid warming event.(Courtesy of Jeffrey Severinghaus)
Note: Austin Keating is a Comer Scholar, a Medill scholarship program supported by the Comer Family Foundation to promote graduate studies in environmental journalism.
Taiwan has faced water shortages for decades – and the Chicago area may face them within the next 20 years as aquifer levels for well water drop while Great Lakes water use is limited by by an interstate compact.
As drought conditions worsen worldwide due to global warming, improved water conservation and efficiency systems become increasingly necessary. National Taiwan University (NTU), a prestigious research institution located in Taipei, is seeking to harness the power of the international science community here and globally to propel cities into a more sustainable future.
The Dragon Gate Program of National Taiwan University, in collaboration with Argonne National Laboratory west of Chicago, and Northwestern University are pioneering water reclamation and reuse technologies. One is a filtration systems that produce clean water from salt water or wastewater. The project is in its third year.
Yupo Lin, an electrochemical engineer at ANL, is leading the research team to scale up a filtration technology called Resin Wafer Electrodeionization (RW-EDI). The process purifies wastewater by pushing it through a series of porous ion exchange membranes with an electric field on either side. The result is an energy-efficient and economically viable approach to water reclamation, Lin said.
“We don’t have many natural resources in Taiwan,” said Lin. So far, the Argonne RW-EDI process has only been demonstrated as a pilot program. But the team hopes to soon create systems that can be used commercially and improve water efficiency on a large scale. Plans are underway to do just that.
“We’re doing this research to solve problems that South Taiwan is facing,” said postdoctoral fellow Ming-Huang Wang. “We want to create a versatile technology.”
Wang works with the Carbon Cycle Research Center at NTU, but is now spending 10 months in the Energy Systems Division at ANL, where he is working with Lin on water reuse technologies that could be applied in Taiwan and elsewhere as water shortages spread due to climate change.
RW-EDI does not purify wastewater to the extent that it is drinkable. However, the brackish or semi-pure water that is extracted can still be used for numerous purposes.
“We tend to think that most of the water that’s used is what people drink, but that’s not true,” said Aaron Packman, professor of civil and environmental engineering at Northwestern University. He is partnering with Lin, Argonne, and NTU on the RW-EDI project. “One of the strategies that we’re looking at is to try to separate the drinking water from industrial water use,” he said. The technology could remove compounds that are problematic for industry to produce water that can be used for cooling and other purposes.
“You don’t have to treat water to drinking standards if it’s going to be used for industrial purposes,” said Packman, part of the Northwestern-Argonne Institute for Science and Engineering. “There are ways to be more efficient.”
Because power plants are the largest consumers of water in the U.S., using more efficient sources for cooling water would have a significant impact on the water supply. It’s hard to imagine that a place like Chicago, which sits right alongside Lake Michigan, could ever face water shortages, but estimates indicate that industrial and economic development could be limited in the city within the next 20 years. “If we find a way to reuse the wastewater that opens up a huge amount of new development potential,” said Packman.
The NTU-ANL-NU partnership and the Dragon Gate Program have created opportunities for scientists from both institutions to contribute to technologies that could improve resource management, not just in Chicago and Taipei, but across the globe.
A consortium of global scientists will gather Aug. 5 and 6 at a conference hosted by NTU to explore opportunities for new international collaborations. The symposium isl focusing on clean water technologies, the vital links between urban food, energy and water supplies, and green infrastructure. Lin and Packman will be addressing these topics at the symposium, along with Seth Snyder, a mechanical engineering professor at Northwestern, and scientists from several institutions.
“We are aiming for integrated water-energy solutions including a mixture of technological innovation and integration of engineered systems with natural systems,” said Packman. The collaboration between leading scientists in this field could produce the ingenuity that will allow cities to continue to function as resource scarcity becomes a more imminent threat.
Photo at Top: Eaglle Harbor (Abigail Foertner/Medill)
The scientists agree that as temperatures and carbon dioxide levels rise, the Earth faces increased threats of fresh water shortages, coastal flooding and extreme weather events. Trying to determine the speed and potential impact of a changing climate, Comer scientists representing institutions across the world pursue field research from Africa to the Swiss Alps.
“This ultimately comes down to a simple thing as it is easier to break something than to build it,” said Richard Alley, professor of geosciences at Pennsylvania State University. “When we think about what we are doing to the climate, cranking up CO2, it’s very, very unlikely that it turns the planet into Eden.”
The researchers found that much of their data from all over the globe seemed to coalesce around a few key ranges in time, suggesting that the researchers from across disciplines might be zeroing on a much more precise picture about the nature of climate change through the ages.
Much of the research on display looked to the past to better predict possible climate responses, from the collapse of ice sheets in Greenland and Antarctica to historical variations in volcanic activity. Presenters also discussed advances in green technology and how our ancestors adapted to previous changes in climate.
One of the major questions facing the scientific community is how researchers can effectively communicate the exponential nature of abrupt climate change. Current climate models are built on scientists’ best knowledge about climate indicators like sea level rise, glaciers and the chemical composition of the oceans, but there may be other drivers or effects scientists have yet to decipher. This means that while nearly 200 countries pledged in Paris to limit warming to well below 2 degrees Celsius (3.6 degrees Fahrenheit), the world may soon be reaching a tipping point where this will no longer be possible.
The uncertainties in climate change research should motivate the public and policymakers to do more, not less, to address the potentially devastating consequences of abrupt climate change, said Alley. People buy auto insurance to protect themselves from the uncertainties of having a car accident. The most important story we need to tell about climate change is that adaptation will help the economy, he added.
Author and consultant Philip Conkling told the audience of predominantly scientists that the secret is in telling “character-driven stories about how climate is affecting real people’s lives.” Conkling cofounded the Island Institute in 1983 to examine climate change through the lens of communities along Maine’s sensitive archipelago. Philip Conkling & Associates helps not-for-profits and implement communications goals and strategic plans.
Klaus Lackner, director of the Center for Negative Carbon Emissions and professor at Arizona State University, is already working on a promising technology to sequester carbon from the atmosphere. Mitigation, he said, has to be a solution in order to repair the considerable damage already done by burning carbon. “I am now convinced that we will have to do carbon storage, carbon sequestration or carbon disposal,” said Lackner.
Many of the other scientists at the conference are looking at to the past to see how ancient climate shifts played out, even without human interference. The scientific community is hoping to understand the conditions before, after and during previous warming periods in order to make better predictions about our planet’s future.
Christine Chen, a third-year Ph.D. student at the Massachusetts Institute of Technology, studies lakes in the Andes Mountains in order to predict future precipitation patterns. “Water availability is a huge issue there,” said Chen, referring to the Central Andes region where she conducted her fieldwork. “Reconstructing how precipitation patterns changed in the past is highly relevant to what is happening and what is going to happen in these regions in the future.”
University of Nevada Ph.D. candidate Ben Hatchett is pursuing research that could help us understand the future of drought and water shortages closer to home. His model identifying the influence of temperature and precipitation over time on water levels in western Nevada’s Walker Lake watershed found that drought severity doesn’t all come down to precipitation.
“We can see that the impact of temperature is very important,” Hatchett said. Ongoing drought conditions are “on par” with historic anomalies in terms of precipitation, he said, but warns that the same does not hold true for temperature where megadroughts don’t reflect an earlier precedent.
“The temperature [now] could be pushing us outside the realm of the natural variability,” Hatchett said. With the arid western U.S. projected to warm even more in the future, that means additional pressure applied to strained water resources.
Many presentations showed powerful evidence that something big happened to atmospheric circulation in the Southern Hemisphere approximately18,000 years ago, when glaciers last reached their maximum extent in the last major ice age. Mike Kaplan, geologist at Columbia University, has been working in Patagonia, at the southern tip of the Andes Mountains. Scientists had previously assumed the area only contained records of older ice masses. But during his 2013 field season, Kaplan and his colleagues found glacial deposits dating to that last glacial maximum. Kaplan’s work could provide crucial clues to when exactly the ice age started and ended in the Southern Hemisphere, furthering scientists’ understanding of how the climate system works.
With the world’s glaciers withering away, caves are emerging as an increasingly important setting for scientists to collect climate data. This past summer, Gina Moseley of the University of Innsbruck in Australia led the Northeast Greenland Caves Project. The group studied the mineral build-up in caves that creates formations such as stalagmites and stalactites, called speleothems, in order to try to fill in gaps in Greenland’s ice core records, especially around the last interglacial period – a stretch approximately 130,000 years ago, when warm temperatures disrupted ice formation.
Moseley and her spelunking colleagues are part of an increasingly popular field. The journal Science noted in 2006 that: “For paleoclimate, the past two decades have been the age of the ice core. The next two may be the age of the speleothem,” spire-like mineral deposits in caves that include stalagmites and stalactites.
While scientists have so far observed global warming of just less than a degree, the oceans could be distorting the true extent of the impact on the atmosphere of carbon dioxide emissions from fossil fuels, said Jeff Severinghaus, professor of geosciences at the Scripps Institution of Oceanography, part of the University of California at San Diego.
“The deep ocean is so enormous and it is a huge reservoir of cold water and it is becoming a little less cold right now. It means that it will take about 100 years to realize the full warming of 2 degrees. If we continue to burn fossil fuel we will be committing to more than 2 degrees.”
The implications of forces other than temperature make the climate puzzle even more challenging. Other presenters explored drivers of climate change that we could be missing. For example, Guleed Ali’s research on Mono Lake Basin in California suggested that scientists might have reframe current thinking about temperature and evaporation and consider other factors such as the jet stream.
Low temperatures during Earth’s ancient cold snaps should have meant decreased evaporation, and thus higher lake levels. But Ali’s research suggests that Mono Lake was likely as low as it is today. This data indicates that temperature and evaporation, both of which scientists consider drivers of the lake’s water level, seemed to have had a negligible role.
Ali has hypothesized that the North Atlantic Ocean’s circulation and its jet stream instead controlled climate then and now, “What I think might be controlling these lake levels is the state of the tropical circulation and the state of the North Atlantic Ocean’s circulation,” Ali said. “What I think is a possibility, just working hypothesis… is that the strength of the circulation in the North Atlantic Ocean is the controlling factor of the hydro-climate certainly in Mono Lake and much of western U.S.”
Some of the first scientists to lead the charge in researching climate change help organize the conference each year, including glaciologist George Denton of the University of Maine at Orono. Denton spoke on the collapse of the Antarctic ice sheets but, like other climate veterans at the conference, came to hear from the new generation of climate researchers. Many of them are Denton’s current or former students, presenting findings in a field where he has contributed several decades of research.
Climate change science pioneer Wally Broecker, the first scientist to use the term “global warming” in a 1975 paper for Science, is among the founders of the Comer Foundation’s climate change research program. In 2001, the late entrepreneur and philanthropist Gary Comer sought out Broecker, an oceanographer, geochemist and professor of geology at Columbia University. Partnering with Denton and Alley, the four men created a fellows program working with mentor scientists at 31 institutions to support the next generation of researchers and research on abrupt climate change. Seed money and grants also support seminal research in the field, with more than 125 global research projects on abrupt climate change supported since 2005.
In the opening remarks for the second day of talks, Alley spoke movingly on the origins of the conference and the Comer Family Foundation. Comer, founder of Lands’ End outfitting company and a native Chicagoan, started the foundation in 1986 to promote education, healthcare and the environment.
Dec. 22, 2015
Photo at top: Climate scientists Peter Strand (left) and Aaron Putnam (right) hike through the Altai Mountains of western Mongolia during their summer 2015 field season. Putnam and Strand’s research on the glaciers of central Asia is one of the many projects funded by the Comer Family Foundation. (Sarah Kramer/Medill)