By Morgan Levey, Dec. 11, 2017 –

For Californians reeling from the deadly fires in Northern California and the Oroville Dam crisis that displaced thousands, the record-breaking precipitation levels last year may seem like a silver lining after more than five years of drought.

Yet it’s precisely these massive swings, from prolonged dry periods to extreme rain and mud slides that have increased the state’s vulnerability to environmental catastrophes, stressing water supplies and amplifying flooding hazards.

Taken in April 2016, this picture shows that the snowpack is well below the moss on the trees—typically a way to identify the average annual snow depth—with less snow at lower elevations. (Ben Hatchett)

Experts believe climate change and global warming are the culprits for this extreme weather and warn that warming is impacting the mountains most severely. One-third of California’s water supply comes from snowpack in the Sierra Nevada mountains and snowpack reservoir that builds up during winter is in rapid decline. The Sierra Nevada is a moderate-elevation mountain range, highly susceptible to rising temperatures that change the snow level, or the point at which snow turns to rain in the atmosphere during storms.

Climate scientists are finding that it’s not just warming temperatures that are causing the transition from snow to rain but also the altering intensity and variability of winter storms in the Sierra Nevada.

“It appears that the storms themselves are getting a lot warmer,” said Benjamin Hatchett, a hydrometeorologist at the Desert Research Institute in Reno, devoted to studying natural and human-induced environmental changes. According to a new paper published in the journal Water by Hatchett and a team of climate scientists, the combined effects of rising sea surface temperatures and warming background air temperatures make conditions more favorable for warmer and wetter storms landing in the Sierra Nevada. Prolonged periods of dry weather between storms only exacerbates the water resource problems caused by rainier winter storms. The rainier winter downpours cause greater risk of flooding and leave little snowpack to stream into the water supply during summer.

Ben Hatchett shows the impact of thinning snowpack for California water supplies, presenting at the annual Comer Abrupt Climate Conference this fall. (Morgan Levey/ Medill)

“The rule of thumb is a handful of good storms make up the bulk of your water year,” said Michael Anderson, California’s state climatologist in the Department of Water Resources. But the hope is that most of these storms bring snow that stays frozen through the winter. While 2017 did bring record-breaking levels of precipitation, its snowpack was nowhere near the record-setting snowpack levels in 1983, according to Anderson.

California’s state water resource infrastructure is woefully underprepared for this type of climate shift. And it’s not just California. Nevada  also relies heavily on water supplies from melting snow.  The snowpack essentially acts as a secondary reservoir for the states’ water management systems. “If you don’t have a snowpack then you don’t have that ability for that spring refill, or limited opportunity for it. It puts more pressure on the summer water management objectives,” Anderson said.

Hatchett analyzed recorded snow-level data over the past decade and discovered that the snow for winter storms has risen approximately 1,200 feet in altitutde in the atmosphere between the beginning and end of the last ten years. Meanwhile, since 1951, the snow fraction or percent of precipitation that falls in a given time as snow, has steadily declined by about three percent each year.

“Over 10 years that’s 30 percent less precipitation falling as snow, so that can make a significant impact on our water resources,” Hatchett said. The last 10 years has been the steepest decadal decline in snow fraction over the past 67 years.

A precipitation map of the Western United States showing an atmospheric river making landfall. This storm resulted in the Oroville Dam overflow, forcing almost 200,000 people to evacuate their homes. Hatchett’s paper shows how these kinds of storms have both extreme precipitation and high snow levels, which combined with warming sea surface temperatures, can favor rainier than average winters. (Ben Hatchett)

Since the Sierra Nevada is a maritime mountain range, it’s highly influenced by its proximity to the Pacific Ocean. A major component of climate change is warming sea-surface temperatures, making conditions preferable for atmospheric rivers, or long, narrow filaments of water vapor in the atmosphere that “favor wetter, warmer, higher snow-level types of storms,” Hatchett says. With increased evaporation potential from the warming, atmospheric rivers pick up energy and moisture across the ocean and make landfall with more intensity and variability.  

“In California, we actually see precipitation totals associated with atmospheric rivers that rival that of hurricanes in the southeast United States,” Hatchett added. What Hatchett and his team are discovering is that the rise in sea-surface temperatures correspond with changes to the structure of winter storms, forcing the snow level to higher altitudes in the atmosphere and making less of this precipitation fall as snow.

Amid background warming and drying, stronger and more frequent atmospheric rivers are projected for the coming years. “I think the last couple years might look like a window into the future where we can have these persistent, very dry and warm years and then we might have one just awesome super wet year,” Hatchett said.

Long periods of dry weather increase opportunities for evapotranspiration, creating stress for water management systems and reducing water availability as temperatures rise. What does this mean for Californians? Basically the warmer the weather gets, the more often the Sierra Nevada will experience prolonged periods of drought punctuated by moments of heavy precipitation.

Hatchett’s research is key in assisting state officials regulate reservoirs and flood control. Anderson said the Department of Water Resources is dependent on this data to forecast winter storms. “The better we forecast them, the better we can start managing water that we expect to come out of them. Either as snow or as rain.”

This is not just a West Coast issue. Globally, changes in the climate system will force infrastructure to adapt. “We’ve built an infrastructure for a world that is changing,” said Richard Alley, a professor of geosciences and associate of the Earth and Environmental Systems Institute at Pennsylvania State University. “We have counted on snow pack to be our reservoir. And now we’re not going to have it because it’s reducing. And this is true in the Himalayas and this is true in California.”

Photo at top: A snowless landscape is becoming the norm in Tahoe, as seen in this photo taken early in the 2017 season at Squaw Valley. (David Metres/Courtesy of Ben Hatchett)

Note: Morgan Levey is a Comer Scholar, a Medill scholarship program supported by the Comer Family Foundation to promote graduate studies in environmental journalism. 


By Morgan Levey, Dec. 16, 2017 –

Elevation map of the coastline of Maine. (From glacial geologist Brenda Hall’s presentation at the Comer Abrupt Climate Change Conference)

We think of rising fossil fuel use and the resulting carbon dioxide emissions as key catalysts of climate change in today’s warming world. And changes in climate throughout Earth’s history had many drivers, including geological forces, orbital cycles, ocean circulation and a litany of planetary mechanisms that happen on a microcosmic scale. Now imagine that there is another way for Earth’s temperatures to rise rapidly – one we’re not aware of as yet beyond a few clues and one with the potential to amplify today’s global warming.

A little over 17,000 years ago, Earth was well past the peak of the last great ice age and the Southern Hemisphere had begun shifting into the warmer climate we know today. Globally, however, this was not the case. The North Atlantic was experiencing one of the coldest periods of time in the region’s history. Yet scientists are beginning to believe that, although winters were extraordinarily cold, summer temperatures might have been fairly mild in the North Atlantic during this time, warm enough that the ice sheet covering the region may have begun retreating. If that were true, new research suggests that a new mechanism exists, one with the capacity to quickly warm the entire globe at once, at least on a seasonal basis.

Brenda Hall presenting her research at the Comer Abrupt Climate Change Conference this fall. (Morgan Levey/ Medill)

“This is still under study, but our work indicates the end of the ice age may have been rapid,” says Brenda Hall, a glacial geologist at the University of Maine. Climate scientists such as Brenda Hall are urgently trying to put all the pieces together from the past to better predict where human activities may be taking climate now. She’s attempting to chronologically map the retreat of the North American glacial mass through Maine roughly 17,000 years ago in an effort to understand the mechanism that might have triggered warming in this area.

During the last ice age carbon dioxide was trapped in the depths of the Southern Ocean. When deglaciation began, normal ocean circulation resumed and the trapped carbon dioxide was slowly released into the atmosphere. But Hall thinks warming might have occurred so quickly that temperatures may have risen prior to much rise in carbon dioxide levels.

“This may indicate a reduced role for carbon dioxide in causing the warming [then], and it also indicates that another mechanism is present that can cause rapid global warming,” Hall says.

That doesn’t mean that carbon dioxide – driven by fossil fuel emissions to the highest levels in at least a million years – isn’t forcing global warming now. But this other mechanism Hall is investigating could turn up the thermostat even more.

A lineage of research

The impetus for Hall’s research in Maine started with her mentor, George Denton, her Ph.D. advisor in the 1990s. Denton is a glaciologist whose research for tracking glacial retreat has been so fundamental to the field that he has not one, but two glaciers in Antarctica named after him.

George Denton explores the important clues about abrupt climate changes revealed by the end of the ice ages. (2016/Medill Photo)

Denton, with fellow climate scientists Richard Alley and Wallace Broecker, and philanthropist Gary Comer, who supported widespread climate research, published a paper in 2005 based on fieldwork  they had conducted in Greenland. They had discovered an inconsistency in the annual temperature records preserved in physical characteristics of the past during the Younger Dryas, a period of moderate glaciation that started roughly 13,000 years ago.

Glacial geological fieldwork involved dating beryllium-10 isotopes found in samples of rocks taken from glacial moraines, lines of boulders that trace what was once the edge of glaciers and ice sheets, as well as boring ice core samples and dating the pockets of air trapped inside. From the moraines that Denton and the others were dating, the team learned that temperatures during the Younger Dryas were only shifting a few degrees. However, previously published data from ice cores bored recorded a much larger change of 15 degrees Celsius from the same area.

The Younger Dryas marks an era when the North Atlantic region was suddenly thrown back into a near-glacial state as the rest of the world thawed almost completely. Like the era Hall is studying, it was thought to be bitterly cold. The small shift in temperature recorded in the moraines led to the belief that varying temperatures between seasons could account for the ice core shift. While the winters in the region were frigidly cold, the summers may have been quite moderate.

Hall’s research

Hall began to wonder if seasonality was having an effect on ice sheets during other periods of extreme cold in the North Atlantic. Around 17,000 years ago Earth was warming and glaciers were melting from the Southern Hemisphere to the Swiss Alps. “And so that made us wonder, what about the ice sheets?” says Hall.

Hall recently presented her findings at the Comer Climate Conference in southwestern Wisconsin, an annual meeting of climate scientists who have received research funding from the Comer Family Foundation.

Hall’s work is in its infancy, as she gets the dates back from the lab and beginning to analyze her results. But her initial data is proving consistent with her hypothesis. The ice sheets were likely retreating.

Traditionally it is believed that the climate of the hemispheres is out of phase, driven by a bipolar see-saw mechanism, a roughly 1,500 year cycle based on ocean circulation where one pole warms and the other cools. The recorded prevalence of seasonality suggests another mechanism might be at play, one that also “would have to be able to affect the entire globe at once – at least in summer,” Hall says.

She acknowledges that this suggestion is highly controversial, but her initial findings are further confirmation of this. “The bipolar seesaw – if it exists – would only occur in the winter,” Hall says.

Climate scientists, suhc as Hall, map the warming and cooling trends that have occurred throughout our planet’s lifespan in an effort to track the causality of individual factors on climate changes. Earth is large, so a lot of this happens at the level of regions or continents. When a force affects the whole planet, it’s significant. And in today’s warming world, where we are driving carbon dioxide levels to unprecedented heights, it means that warming could be amplified by forces we are only beginning to discover, let alone understand.

The lineage continues

On the other side of the North Atlantic, Gordon Bromley, a glacial geologist and former student of Hall’s, is conducting similar studies – trying to chronologically map the retreat of the ice sheet – but through Scotland.

Gordon Bromley presenting his research on Scotland at the Comer Climate Conference (Morgan Levey/ Medill)

“We’re using exactly the same techniques, same philosophy as we approach it,” says Bromley who also presented his latest findings at the Comer Climate Conference. His results so far have matched Hall’s. “I was pleased to see the same signal, same recession, during the periods that we think our conceptual model says it should be retreating, that is happening on the west side of the Atlantic and on the east.”

Like Hall’s research, Bromley’s Scottish work is building upon previous evidence of global ice sheet retreats around the same period of time. “I’d say that Brenda’s New England work and our Scottish work both grew organically and quite separately from the same line of inquiry. That they are converging attests to the global nature of abrupt climate change,” says Bromley.

For Bromley and Hall, the similarity in results is encouraging, but the work is also tied to a legacy that both are proud to be a part of.

“The way that George trained Brenda and Brenda trained me – hopefully I can train my students that well. It’s like being part of the family business,” says Bromley.

Elevation map of the coastline of Maine. (From Brenda Hall’s presentation at the Comer Abrupt Climate Change Conference)

Note: Morgan Levey is a Comer Scholar, a Medill scholarship program supported by the Comer Family Foundation to promote graduate studies in environmental journalism.


By Morgan Levey –

Vivien Rivera with a rain gauge at Gensburg Markham Prairie (Liliana Herndandez Gonzalez/ ISEN)

“You can ask the question, well do you expect this to look like the city or do you expect it to look like pristine prairie? And the answer is it’s going to be somewhere in between,” says Aaron Packman, professor in the Department of Civil and Environmental Engineering at Northwestern University and director of the Center for Water Research.

Packman’s question refers to levels of contaminants in the soil and water at Gensburg Markham Prairie, part of Indian Boundary Prairies, a remnant ecosystem just 20 miles southwest of Chicago. Over the past year the Institute of Sustainability and Energy at Northwestern University has been collecting data on the prairie site as part of an effort to study the benefits of urban green spaces for cities.

“People are designing green spaces, for example green roofs, but there is no data available about the benefits of these green spaces — for example soil water retention, or improvement of water quality, air quality,” says Liliana Hernandez Gonzalez a Ph.D student at Northwestern University and one of the project’s leads. “With high frequency data we can get models to understand them better.”

Liliana Hernandez Gonzalez, a Ph.D. student at Northwestern University, conducts water sampling at Gensburg Markham Prairie (Vivien Rivera/ ISEN)

NU students in collaboration with ISEN presented the data they’ve collected over the past year at Gensburg Markham Prairie to members of The Nature Conservancy in an annual update for the partnership at Indian Boundary. The prairie site is owned by Northeastern Illinois University and The Nature Conservancy and managed by the conservancy. Gensburg Markham Prairie alone covers over 100 acres of well-preserved grassland, amid housing developments and highways.

The data covers everything from water levels and soil moisture to levels of outside contaminants and is difficult to assess. The ISEN team did find lead and zinc traces in the topsoil and copper traces in the water table. But the levels were less than 3 milligrams per meter, the EPA’s standard for levels of concern, and far below the average background levels for the state of Illinois.  

“Those background levels are coming from the EPA, from a study they did in 1994,” says Gonzalez. “They took like 200 samples in the entire state and, near our site, they only took two samples. But that’s the data that’s available right now.” This outdated study is leading the team to look for other data sets from sites, preferably other prairies in the Midwest region.

A waggle node sensor installed at Paintbrush Prairie (Liliana Hernandez Gonzalez/ ISEN)

To do that, the ISEN team installed 23 sensors in Gensburg Markham Prairie that measure soil moisture and water levels. Along with regularly  sampling the soil and water, the team also installed a waggle node, technology developed by Argonne National Laboratory to collect real-time measurements of  humidity, temperature, air quality and other environmental factors and transmit it via wireless internet to an open-source server.

So far the NU team has one of Argonne’s waggle nodes installed, as it’s dependent on power. “The next phase is to move them to the middle of the prairie, so then we need a solar powered waggle, which we’re working on now,” says Packman. “From there you could take them anywhere.”

An ISEN team presentation for the group at the prairie looked at potential areas of collaboration with The Nature Conservancy, particularly in areas of how the soil and water samples can inform the ecological restoration of the site.

“We, the NU team, don’t have expertise in conservation ecology,” says Packman.“Examples of new directions from the discussion with TNC include assessing the effects of urban inputs on degradation of prairie habitat in nature preserves like GMP, monitoring and controlling water levels for migratory bird habitat in restored wetlands, and use of the video cameras on the waggle nodes to obtain time-series data on plant communities.”

The effects that winter road salt has on the site is one of the areas of research that both organizations see as providing benefit for future management of the prairie.

“We dump massive amounts of salt into our waterways every winter. What do we see [from] that? There’s not enough research done,” says John Legge, Chicago Conservation Director for The Nature Conservancy. “It’s kind of mindblowing.”

In the last samples that ISEN analyzed, taken just two to three weeks before the presentation and three months after the last snow, higher concentrations of magnesium and calcium, key ingredients in road salt, were found in drainage ditches near the roads than in the middle of the prairie, according to Gonzalez.

“But they’re still lower than the background concentrations in Illinois,” says Gonzalez. “We took them in the summer. We’re planning to do more sampling in the winter and we’re also going to install some electrical conductivity sensors in water and soil and then we can get data all year, like high frequency data of these salt concentrations.”

All of the research at the prairie can be summarized as concern for the health of this rare remnant ecosystem’ and the need to gauge the human impact on the site.

“We think of this site as having huge value because of how pristine it is. Without having been plowed with having clearly some of the highest levels of plant and insect biodiversity in prairie remnants in Illinois. Just as a reference for what much of the state once was,” says Legge.

But it’s also essential for other sites that need ecological restoration.

“As others are working to recreate prairie habitat on areas that have had some other agricultural or other impacts, what are we aiming for?”

See related story: Prairie Plays Key Role in Chicago’s Flood Management



Travis Kuntzelman, a restoration manager with The Nature Conservancy, leads a tour for a group from the Institute for Sustainability and Energy at Northwestern University. (Morgan Levey/ Medill)

By Morgan Levey, Aug. 10, 2017 –

“You could get lost out here,” laughed Vivien Rivera. Big bluestem grass growing nearly 10 feet high towered over Rivera’s head as she walked through Markham Prairie North, part of Indian Boundary Prairies near Markham. The dense, prairie landscape is filled with sweet blackeyed susan, bergamot, blue vervain, marsh blazingstar and other native grasses that survived decades of industrialization.

“Big bluestem [grass] is just a rainbow of colors,” says Travis Kuntzelman, a restoration manager with The Nature Conservancy. “That’s its namesake, the blue part of the stem there,” continues Kuntzelman as he points to a small segment of the grass shoot. “But it’s just full of colors.”

Indian Boundary Prairies, a world away from Chicago though just 20 miles south, encompass the largest remaining remnant prairie in the state of Illinois. The nearly 500 acres of open land, owned by Northeastern Illinois University and The Nature Conservancy and managed by The Nature Conservancy, escaped the plow as well as development and remains one of the most biodiverse places in the Midwest.


William Miller, professor of chemical and biological engineering at Northwestern University, walks through big bluestem grasses at Markham Prairie North, bordered by I-294 to the east. (Morgan Levey/ Medill)

“The Chicago wilderness has a whole series of intact small remnant habitats that hold a lot of the biodiversity — the rare biodiversity — that was here at the time of European finding of this area,” says Karl Gnaedinger, project manager for Indiana Boundary Prairies for The Nature Conservancy. IBP consists of five prairies separated by housing developments and roads. Despite highway borders, the prairie is considered a reference ecosystem — a biological standard for other restoration initiatives.

“Our prairie sites are an opportunity to help especially [our] urban community better understand that biodiversity isn’t just something that’s off in the Amazon, or in coral reefs, but that there’s really significant biodiversity around us,” says John Legge, Chicago Conservation Director for The Nature Conservancy.

Rivera, a second-year Ph.D. student at Northwestern University toured some of the high-quality areas of Indian Boundary Prairie in late July with her research team from the Institute for Sustainability and Energy at Northwestern and members of The Nature Conservancy, the organization that manages the prairie.

Rivera and the team from ISEN have been analyzing environmental samples from Gensburg Markham Prairie for the past year. They installed 24 sensors, capturing everything from soil moisture and water levels to light, humidity and air quality. Their goal is to assess the health of the entire Indian Boundary Prairies and collect data that shows how prairies, with their deep web of roots, help purify water, prevent flooding and control soil erosion.  

Native prairie plant marsh blazingstar (Liatris spicata) grows in Markham Prairie North. (Morgan Levey/ Medill)

“The aim of our study at IBP is to evaluate both the benefits of urban green space to the surrounding community and the impacts that urbanization has on the prairie,” says Rivera, one of the project’s leads.

Prairies are ecologically essential because they have the ability to store water both on their surface and underground. Indian Boundary Prairies help manage Chicago’s stormwater runoff and alleviates flooding in the surrounding area.

“Flooding is an enormous concern in the Chicago area. Low lying city, rivers running through it, right by the lake, so generally speaking, flood prone.” says Aaron Packman, professor in the Department of Civil and Environmental Engineering at Northwestern University and director of the university’s Center for Water Research. “We are hoping to use the information we gain from GMP and our other sites to be able to predict the behavior of urban green spaces and design networks of green spaces to achieve objectives like flood control,” continues Packman.

Some of the technology that the ISEN team is deploying in the field was developed by Argonne National Laboratory for their “Array of Things” sensor project conducted in collaboration with the University of Chicago. Their sensor nodes have the ability to measure and then collect real-time data on air quality, light, temperature and an array of other environmental factors.

We are “using information we know about the site like soil types, and where water has historically been to try and figure out A, why it is that way, and B, where water will be in the future,” Rivera says. The team also wants to know how much water gets stored and how much gets transmitted in and out of the prairie. Rivera says they are using the data to begin developing a groundwater model for Gensburg Markham.

The built environment has radically impacted biodiversity and ecology across the world. Prairie landscapes are essential in the Midwest to flora and fauna that aren’t able to adapt to human habitats. “We think of IBP as a sanctuary for plants and animals that need help now, and that definition of what needs help now will change over time,” says Gnaedinger.

Indian Boundary Prairies, a world away though only 20 miles south of Chicago. (HerbertSsegane/Argonne National Laboratory)

“For the last few years, there’s [been] a substantial concern of increasing flooding related to climate change,” says Packman. The Midwest has endured a 37 percent increase from 1958-2012 in precipitation falling in very heavy events – the heaviest one percent of all daily events, according to a 2013 report by NOAA’s National Climate and Development Advisory Committee.

“Under climate change and changes with how the surrounding areas are being managed, these sites are getting new inputs and outputs that didn’t exist. We might need to make some changes within the prairie to make them behave more like they used with changes with inputs and outputs,” says Rivera.

Prairie grasslands once covered much of Illinois as a habitat for bison, deer and countless other animals. But now it takes a huge amount of management and maintenance to keep native plant and animal species thriving. “The prairies are islands, subject to edge effect and invasive species moving in, [We] have changed the hydrology radically. All these things make great impacts,” says Gnaedinger.

Conrolled burns are one of the methods for maintaining prairie health by killing invasive species and promoting regrowth. Burns occur every two to three years, according to Kuntzelman, “We have rotating patterns so it’s not all at once. Some areas need it more than others and those get burned every year.”

To the researchers the burns exemplify the vigor of the prairie’s productive ecology. “You should see it when we’re out here in the winter,” says Rivera as she wades through waist-deep vegetation. “Everything freezes and dies and it’s all open fields.” But for now, the prairie is thriving with an ocean of grasses.

See related story: Sensors Give a Deeper Glimpse into Illinois Prairie Health and Human Impact

Photo at top: A tour of Paintbrush Prairie at Indian Boundary Prairies south of Chicago. (Morgan Levey/Medill)

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