Scientific (r)evolution

Nelson research center stays ahead of changing climate

March 15, 2013 | by STEVE POMPLUN

It was the year in which the Beatles released their first single, “Love Me Do.” The space race was heating up, the civil rights movement was growing and U.S. involvement in Vietnam was escalating. Casting a shadow over everything, amplified by the Cuban missile crisis, was the ongoing Cold War.

It was 1962 and climate change was nowhere to be found on any list of public or political concerns – and yet that was the year the Center for Climatic Research (CCR) was established at UW-Madison. Its scientific mission: to understand how the climate works and why it changes. Greenhouse gases such as carbon dioxide – now understood to be a key determinant of future climate – were not widely thought to play a significant role.

John Kutzbach, a former director of the Nelson
Institute Center for Climatic Research. Photo
courtesy UW-Madison Archives, S09890.

“There was a recognition that climate had changed in the past, manifested in events like the ice ages,” says John Kutzbach, former CCR director and an emeritus professor of atmospheric and oceanic sciences. “But the things that people were primarily thinking of as causes of recent change were aerosols, volcanoes, perhaps solar  activity. The long-term effort to monitor the rise of carbon dioxide had just begun.”

In fact, says Kutzbach, the notion that human activities could in any way affect the climate had little support in the scientific community.

But Reid Bryson saw things differently. Bryson, an atmospheric scientist who had established UW-Madison’s meteorology department in 1948, had long been interested in the role of climate in the rise and fall of human cultures. He had come to believe that climate change had determined the fate of a number of societies – for example, the Viking settlements in Greenland – and that human activities could, in turn, influence the climate.

Bryson, who died in 2008, argued that human-induced climate change could threaten food supplies and other critical resources – but his focus was primarily on land use patterns rather than the greenhouse effect. Case in point: the fall of a once-thriving culture in India nearly 3,000 years ago.

“Reid had this idea that the rise and fall of Harappan civilization had been related to climate” says Kutzbach. “He developed the idea of a feedback process: Overgrazing of an area along the Indus River, which had once been a green, moist environment, caused loss of vegetation, which caused a dusty atmosphere, which reflected sunlight, which caused additional lack of rainfall.”

Widening the field

Bryson had a voracious appetite for observational data. He measured land cover in India, solar reflectance in northern Canada, ice cover on Lake Mendota and other phenomena in far-flung locations. He saw the climate as systemically linked to land and water, to vegetation, phenology and agriculture, to human activities and the fate of civilizations, driving the science of climatology in new directions and broadening its reach.

Reid Bryson pioneered the establishment of inter-
disciplinary environmental research at UW-Madison.

But investigating all these links required a broad set of evidence – data that could only be gathered from things like lake sediments and fossil pollen, using radiocarbon dating and other tools and techniques beyond those typically employed in atmospheric science. Bryson wrote a proposal to the National Science Foundation to establish an interdisciplinary climate research center that would include laboratories to study tree rings, pollen and sediments and perform radiocarbon analyses.

“Up until that time, something like that would have been housed in a geology or archaeology department, and the chance of it being fostered by a climate scientist was close to zero,” says Kutzbach. “It was absolutely a first.”

Bryson’s revolutionary ideas drew Kutzbach back to his alma mater in 1963 to earn a Ph.D. Kutzbach joined the faculty in 1966, having developed a statistical technique to sort through volumes of data and identify large-scale weather patterns such as the North Atlantic Oscillation. He joined one of the world’s leading meteorology departments, with internationally known faculty that included Verner Suomi, Robert Ragotzkie, Heinz Lettau and Lyle Horn.

Bryson, meanwhile, continued to pioneer the establishment of interdisciplinary research into the environment – during a time when most scientists were content to work in their own labs with few collaborators. He organized a university-wide committee that ultimately recommended the creation of an interdisciplinary environmental studies program. In 1970, the university established the Institute for Environmental Studies – later renamed the Nelson Institute in honor of the late U.S. Senator Gaylord Nelson – with Bryson as its first director. He appointed Kutzbach to lead CCR.

Cause and effect

Bryson’s ideas about climate were gaining traction as part of a broader recognition that people were altering the planet on a scale never seen before. Widely considered one of the world’s leading climate scientists, he testified before Congress on the issue in 1974.

But he was not focused on global warming, even as greenhouse gas emissions were beginning to be seen as a potentially serious issue among other scientists. He remained an outspoken advocate of the idea that humans were causing a lot of changes, and that global cooling was also possible due to rising levels of aerosols – particles or droplets of pollution from combustion and industrial activity.

A 1974 Wisconsin State Journal article reports on
Bryson's research into the agricultural risks of
climate change. Image courtesy UW-Madison Archives.

In 1977, in the midst of his federally funded Climate and Food Project, Bryson published Climates of Hunger: Mankind and the World’s Changing Weather, in which he and co-author Thomas Murray argued that climate change driven by aerosols was causing shifts in rain belts and agricultural regions, leading to starvation. The book, written for a popular audience, sold well and echoes today in the public discourse over climate change and food security.

Kutzbach, too, was engaging in the growing international conversation about global change, but from a different perspective. He was invited to serve on a National Academy of Sciences committee to assess the scientific basis for climate change resulting from anthropogenic carbon dioxide emissions.

The groundbreaking 1979 “Charney report,” as it is often called, “really put the finger on carbon dioxide as a very important consideration for future climates,” says Kutzbach. Its comprehensive review of the state of climate modeling and the potential for models to test hypotheses about the causes of climate change was deeply influential to policy makers and the scientific community, setting research agendas for the following decade.

“There had been a national emphasis on developing a high-quality climate model that would mimic the behavior of the world and allow you to do, in a sense, laboratory experiments for the first time,” he says. “What happens if we change carbon dioxide? What happens if we change aerosols? We could then compare that with the data.”

Kutzbach says climate models, along with the parallel development of satellite observation capabilities, were reaching a point where they could produce plausible results – especially when they could prove their validity by reproducing the past. Kutzbach was the first to use these powerful computer models as quantitative tools to investigate climate history.

“The bulk of the climate community was thinking of climate models as a way to simulate the present, year-to-year variability, and to look at the future,” he explains. “But I was fascinated to look backward, to ask, ‘What did cause ice ages? What caused the Sahel to be wet 6,000 years ago?’ Models could help quantitatively answer those kinds of questions.”

Proving the past

Kutzbach was also the first to use models to verify that slow “wobbles” in the Earth’s orbit – manifested in the shape of its orbital path and in the angle and orientation of its axis – were primary drivers of climate change over thousands of years, a phenomenon first known as Milankovitch cycles. These cycles, it turned out, drove both the advance and retreat of ice sheets in the high latitudes and the waxing and waning of monsoonal rain in the subtropics. 

CCR was at the forefront of paleo-
climatology, or the study of past
climates. Ancient spruce pollen
image courtesy UW-Madison Archives.

“These variations would change seasonal sunlight that could, on the one hand, make the monsoons stronger,” he says. “If you had warmer summers, you’d get strong monsoons. But if you had really cold summers, you had the chance that snow cover wouldn’t melt in Canada and you might begin to build up ice ages.”

The idea that orbital variations might cause ice ages was proposed as early as the 1870s, but Kutzbach was the first to test it quantitatively – pioneering work that would later see him elected to the National Academy of Sciences. “We were able to show that these orbital variations are a big enough factor to account for the large-scale climate changes of the last million years,” he explains.

Paleoclimatology – the study of past climates – was a fast-growing field, and CCR was at the forefront, building on the interdisciplinary foundation laid by Bryson.

In 1977, Kutzbach and Thompson Webb, a Bryson Ph.D. student who went on to his own illustrious career at Brown University, came up with an idea that would put CCR at the center of the first “big science” project in paleoclimatology. They landed a major grant from the National Science Foundation and U.S. Department of Energy to characterize and map global climate, vegetation and hydrological changes spanning 21,000 years, since the peak of the last ice age.

The Cooperative Holocene Mapping Project (COHMAP) was an enormous undertaking, involving nearly 50 scientists at five universities. They set out to reconstruct and map the past climate using evidence such as fossil pollen, marine plankton and lake sediments, creating snapshots at 3,000-year intervals in locations around the planet.

Kutzbach’s innovation – using climate models to explain the observed changes – was the critical glue of the project. Both the sharing of data among scientists and the building of interdisciplinary teams of climate modelers, oceanographers, ecologists and geologists was revolutionary, and a precursor to the modern practice of integrated earth system science. This effort ultimately gave rise to the Paleoclimate Model Intercomparison Project, whose results are used by the Intergovernmental Panel on Climate Change to understand the natural and human drivers of climate change.

CCR continues to be a world leader in historical climate modeling, led by Zhengyu Liu. Liu, a professor of atmospheric and oceanic sciences, succeeded Kutzbach as CCR director in 2002 and has received his own accolades, elected a fellow of the American Geophysical Union and the American Meteorological Society.

Former directors Zhengyu Liu, Reid Bryson and John
Kutzbach, left to right, helped position CCR as a world
leader in climate research.

Liu and staff scientist Feng He were part of a team that recently completed a project decades in the making: a comprehensive and continuous simulation of the climate from the last glacial maximum to the present, showing how meltwater from receding ice sheets could trigger abrupt changes in the ocean and atmosphere.

New science, new challenges

Climate models are always evolving, riding on ever-faster computer processing capabilities and developing higher-resolution and ever-increasing realism in their representations of the earth system. At the same time, the urgency of climate change now calls for new science and a closer connection to decision-making.

For example, in the COHMAP days, the most advanced climate models treated the world ocean essentially as an inert slab – able to exchange energy with the atmosphere, but with no ability to circulate. At CCR, Liu has pioneered the development of ocean-atmosphere and ocean-atmosphere-vegetation models that show how feedbacks between these systems are a crucial cause of climate variability, past and present.

One of CCR’s strengths has been its longstanding relationship with UW-Madison’s Department of Atmospheric and Oceanic Sciences, one of the strongest such programs in the world. And the blending of disciplines from across campus, essential to the center from its inception, has never been stronger, with more faculty members, scientists and student researchers involved than at any point in CCR’s past, with access to unprecedented capabilities from models, satellites and other tools.

“The brainpower in CCR today is incredible,” says Kutzbach, describing how CCR has expanded beyond its early roots in climatology into wide-ranging studies across the new field of Earth system science.

The areas of research on which the center was founded still thrive, but a new array of interdisciplinary projects have blossomed on topics like carbon cycles in the Great Lakes, oceans and forests; long-term oscillations in the oceans; Arctic climate feedbacks; and the climatic effect of land use changes thousands of years ago.

And increasingly, CCR’s mission is working with decision-makers to assess climate vulnerability and develop strategies to help society adapt.

“In the 1990s and maybe early 2000s, the goal was stopping climate change,” says current CCR director Jack Williams. “I would say we’ve passed the moment where that goal is possible. Now we’re in a conversation about slowing the rate of climate change and adapting to the changes that are happening now and are going to continue over this century.”

Again, CCR has helped lead the way, developing innovative new partnerships among climate scientists, decision-makers and stakeholders, particularly through the Wisconsin Initiative on Climate Change Impacts.

“CCR has a really important role to play, particularly on adaptation,” Williams says. “A lot of people need the best available science and information about what climate changes are expected over the next several decades, and CCR – because it’s got such a top notch group of scientists from the atmospheric sciences, the biological sciences and the geological sciences – is in a key position to help with this effort.”

It all goes back to Bryson’s vision more than 50 years ago, when he began to stretch the boundaries of climate science. He was well ahead of his time, but others would soon follow.

“Reid’s idea had legs,” says Kutzbach. “When he set up CCR, it was unique. There was nothing like an interdisciplinary climate research group in 1962. But the idea has proven to be so valuable that you now have a lot of centers in this country and around the world that have modeled themselves after CCR.”