Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Photo of skiers © Mark Milford, American Birkebeiner Ski Foundation

Warmer winters with less snowfall affect ski race participation.
© Mark Milford, American Birkebeiner Ski Foundation

February 2010

Preparing to adapt

Natural resource managers and university researchers are focusing on strategies to adapt to climate change in Wisconsin.

Steve Pomplun, Richard Lathrop and Alison Coulson

Long-time Wisconsinites believe they've seen it, and new research proves them right: our state's climate is changing. A team of scientists at the University of Wisconsin-Madison's Nelson Institute for Environmental Studies has documented a significant shift in temperature and precipitation patterns over the past few decades – and what they've found might be a small taste of what lies ahead. The researchers say far greater changes are likely over the next 40 years – changes that could profoundly affect our natural resources, economy, health and sense of place.

Working as part of the Wisconsin Initiative on Climate Change Impacts, or WICCI, the UW-Madison climatologists analyzed a wealth of weather data collected across the state since 1950.Daily temperature and precipitation readings gathered from scores of cooperative weather stations show that temperatures have risen consistent with the global trend.

The numbers might seem modest. Statewide, the annual average temperature has risen by 1.1 degrees Fahrenheit over the past 56 years, and average precipitation has increased by about 10 percent. But the devil is in the details, with big differences across the seasons. For example, temperatures have risen fastest in winter and spring, while summer and fall have actually cooled a bit.

Add geography to the mix and you see even greater variation: winters in northwestern Wisconsin have warmed by as much as 4.5°F.

"We're not seeing as many extended subzero stretches in our winters, and the nights have gotten milder," says Christopher Kucharik, an assistant professor of agronomy and environmental studies at UW-Madison and one of the lead researchers on the project.

The increase in precipitation is concentrated in the south-central and western regions, while northern Wisconsin has been drier, especially in summer. "The increases in precipitation are generally due to an increase in the number of days each year with measurable rain or snow," Kucharik explains.

Feeling the effects

Impacts of the changing climate are being felt in a variety of ways. Lake ice cover, for example, has been declining. UW-Madison limnologist John Magnuson, who co-chairs the WICCI Science Council, has documented a steady decline in the length of time that Wisconsin lakes are frozen over. That can affect ecological conditions such as nutrient cycling and oxygenation within the lakes, as well as habitat for shoreline birds and other species. Ice fishing has also been affected by shorter ice duration.

Other indicators of climate change are seen in the earlier emergence and blossoming of native plants such as forest phlox and false indigo, and in the spring arrivals of some migrating birds, including the eastern phoebe, the rose breasted grosbeak and Wisconsin's state bird, the robin. These kinds of changes have been recorded by Nina Leopold Bradley, Aldo's daughter, who is building a valuable collection of phenological observations at the Leopold Foundation in Baraboo. In simplest terms, spring is coming earlier, and while this might sound nice, it could upset the delicate balance of many important ecosystems.

And then there's the flooding, perhaps the most obvious of the changes we're seeing. Wisconsin has smashed records for the frequency and severity of floods in recent years, resulting in hundreds of millions of dollars in damage to property, crops and infrastructure. The most astounding and iconic of these recent events was the shoreline failure that emptied Lake Delton in June 2008 following a period of successive heavy rainstorms that fell on ground already saturated from record winter snows and excess rainfall in April.

Although no single weather event can be attributed to climate change, climate models project an increase in the frequency of the most intense rainfall events as the world warms. Stormwater system designs throughout the state have been based on hydrologic data that have not been updated in 40 years, and with "100-year" flood events occurring with greater frequency, the statistics, terminology and engineering to manage stormwater may need to be redefined and redesigned.

Modeling Wisconsin's future

The climate researchers also developed a set of future projections as part of their state-based analysis. They used an innovative technique to "downscale" (localize) 14 global climate models used by the International Panel on Climate Change, or IPCC, in its fourth assessment report issued in 2007. The global models, while effective at depicting worldwide climate trends and projections, lack the high resolution needed to analyze regional or state impacts. The Wisconsin team overcame that limitation by combining the results from these global climate models with the same fine-scale weather information used in the historical analysis to predict the range of probable climate change that can be expected in Wisconsin.

The goal was to produce analyses on a scale that would be useful to natural resource managers, municipal leaders, business planners and other decision makers. Both the recent trends and future projections are mapped to a five-by- five-square-mile grid. The historical data were used to validate the modeling and "ground-truth" the projections.

"We've produced a unique resource that combines the world's best estimates of future climate change with historical data collected here in Wisconsin. The result is a remarkably flexible dataset that can be used in a wide variety of assessments," says Daniel Vimont, an assistant professor of atmospheric and oceanic sciences and a member of the Nelson Institute's Center for Climatic Research. "We need to take the next step now, and use these data to identify how our state's natural and built environments can better adapt to the inevitable climate changes we will face."

The projections themselves are stunning. Based on a carbon emissions scenario that assumes continued heavy reliance on fossil fuels well into the future, climate change is predicted to accelerate over the next 40 years. These findings predict the state's annual average temperature will warm by four to nine degrees Fahrenheit by the middle of the century. Winter will continue to warm the most, especially in the northwestern counties, and nights will warm more than days, also mirroring a recent historic trend.

Precipitation changes are harder to model, and the projections are loaded with uncertainty. The researchers cannot say, for example, what summer rainfall will look like by mid-century; the models widely vary. But they can say that winter and spring precipitation is likely to increase across Wisconsin; the average of all 14 model predictions is 20 percent. Combined with the warming winter, this increase in precipitation points toward more frequent freezing rain events, and even rainstorms, in the middle of winter. Higher temperatures may also lead to more springtime thunderstorms and heavy downpours.

Facing big changes

These projections, when viewed alongside the changes of the last five decades, give a sense of the challenges Wisconsin could face. Think of it this way: If an annual temperature increase of a degree or two has already caused observable changes across the landscape in recent years, what will an in- crease of four or seven or nine degrees bring? Models predict an earlier arrival of our last freeze in spring and delays in our first freeze in fall; that could translate to a longer growing season, potentially benefiting agriculture and other activities, but longer and warmer summers would have many negative effects, too. The models imply that winters in Wisconsin will shorten by an average of four weeks. What's at risk if we experience changes of this magnitude?

After all, natural resources and seasonality support a significant portion of Wisconsin's economy, including tourism and outdoor recreation, hunting and fishing, forest products and paper, Great Lakes shipping, agriculture and the dairy industry, and water intensive manufacturing. Winter recreation, including snowmobiling, skiing, and ice fishing, means economic survival for many northern Wisconsin communities, where the social fabric and sense of place is inextricably tied to our seasonal climates.

Photo of Fallison Lake shore © DNR Photo
Fallison Lake, Vilas County, August 2007. Downed trees and brush lie high and dry along the shore due to prolonged drought.
© DNR Photo

In addition, a wide range of plants, animals and ecosystems are adapted to our cold winters. As winters become milder, the natural boundaries of many plant and animal species in the region will be forced northward, and unfamiliar species from farther south, including pests, could move in to replace them. Milder winters with less snow also allow deer populations to swell, meaning more deer browsing damage to forests and crops. Endemic pests such as ticks and harmful crop and forest pests could also proliferate as winter kills are reduced.

So a long list of questions emerges:

  • How will our northern forests fare under much warmer conditions?
  • How will climate change affect outdoor recreation, especially in winter?
  • Does municipal stormwater infrastructure need to be redesigned?
  • Will coldwater fisheries withstand increases in air and water temperatures?
  • Will more invasive species migrate northward into the state and affect aquatic and terrestrial ecosystems?
  • How will warmer weather and heavier rains affect air and water pollution and ultimately human health?

In an attempt to find answers to these and countless other questions, the Wisconsin Initiative on Climate Change Impacts (WICCI) was formed as a collaboration between the Wisconsin Department of Natural Resources and UW-Madison's Nelson Institute, both of which had begun to examine the issue of climate change impacts. Since DNR Secretary Matt Frank and then- Nelson Institute Director Lewis Gilbert signed an agreement to form WICCI in the fall of 2007, the initiative has grown to include representatives from other state and federal agencies, several UW System schools, tribal organizations, businesses and nonprofit groups.

The initiative is distinct from the Governor's Task Force on Global Warming, which was formed to recommend ways to mitigate climate change, primarily by curbing carbon emissions. WICCI, on the other hand, was established as an independent effort to identify and prepare for the consequences of climate change regardless of its cause. The operating principle is that climate change is underway and is gaining momentum. Even if we stop emitting all greenhouse gases tomorrow, changes that are already in the system will continue to develop for at least another century. Adapting to these changes is critical to Wisconsin's future, regardless of how the state decides to reduce the causes of climate change.

"Wisconsin is taking steps to address the causes of climate change, including creation of the Governor's Global Warming Task Force and the signing of a Greenhouse Gas Reduction Accord with 10 other Midwestern states," says DNR Secretary Matt Frank. "WICCI complements these actions by helping communities, businesses and citizens prepare for climate change impacts, even as we work to reduce them."

WICCI is organized to combine scientific research with practical management. The initiative is governed by a science council whose 22 members represent the Department of Natural Resources, the University of Wisconsin system, and other state and federal agencies. A stakeholder advisory committee of utility companies, agriculture, tourism, forestry, public health, environmental organizations and Native American interests helps identify information decision makers will need to respond to climate change. An outreach committee recently formed to help develop ways to disseminate WICCI findings and recommendations.

Assessing the impacts

Key to WICCI's mission are "working groups" that have been created to assess and anticipate how climate change will affect specific Wisconsin natural resources, ecosystems and regions; evaluate potential impacts on industry, agriculture, tourism and other human activities; and recommend practical strategies and solutions that businesses, farmers, public health officials, municipalities, resource managers and other stakeholders can implement. More than 200 scientists, resource managers, experts and practitioners participate in the 16 working groups that have formed so far to address soil conservation, water resources, public health, agriculture, cold- water fisheries, stormwater, wildlife, coastal communities, forestry, loss of winter, and plants and natural communities. Other work groups are investigating climate adaptation, Central Sands hydrology and ecology, Green Bay and Milwaukee community issues.

Some working groups focus on relatively specific questions. The coldwater fisheries group, for example, is looking at the potential consequences of warming for Wisconsin's 10,000 miles of trout streams as well as coldwater lake species such as cisco and lake trout. The group is not limiting its focus to issues of ecology. The health of these trout stream resources could influence the economies of scores of Wisconsin communities that depend on recreational fishing for income.

Other working groups are tackling a broader array of issues. One based in Milwaukee is considering stormwater management, beach contamination, air quality, heat wave emergencies and other factors unique to the urban environment. Another place-based working group focuses on Green Bay and its surrounding watershed.

The release last September of WICCI's study of recent climate trends and future projections is the first of several reports to come. The working groups are compiling their initial assessments this spring and will publish their results in a comprehensive assessment report this fall. It will show which resources are most vulnerable to climate change and suggest strategies for adapting to these predicted changes. The comprehensive assessment will be updated over many years to come, much as the IPCC updates its findings every few years.

Thinking regionally

Climate change does not stop at the state border, and Wisconsin is building relationships with neighboring states to work together on its impacts. WICCI participants are collaborating with agencies, universities and organizations in Minnesota and Michigan, and they're seeking federal support to develop a regional version of the Wisconsin initiative.

And the idea is spreading. WICCI is widely viewed as a model for stakeholders to assess climate change, and requests for meetings and presentations have been coming in from across Wisconsin and from other states and Canada.

Nelson Institute and DNR staff members are working to develop new information tools, including print materials and online resources, to spread the word about WICCI and to educate the public about climate change impacts. The WICCI website holds a growing collection of reports and presentations, including a full and interactive set of detailed maps of recent and projected climate change in Wisconsin. To access these resources and to learn more, visit Wisconsin Initiative on Climate Change Impacts.

Steve Pomplun directs community and alumni relations for the Nelson Institute and coordinates outreach for the Wisconsin Initiative on Climate Change Impacts (WICCI). Richard Lathrop is a DNR research limnologist and co-chair of the WICCI Science Council. Alison Coulson is the WICCI program manager and is employed by both the Nelson Institute and the Department of Natural Resources.