Summer 2010

Northern Wisconsin has become drier, but southern and western Wisconsin have become much wetter, by as much as 7 inches per year. [photo credit: Tim Asplund]
Water Resources Outreach

Wisconsin’s Changing Climate
Water resources are a reflection of a changing climate

By Carolyn Rumery Betz

Scattered storms dropped 1½ inches of rain on southern Wisconsin in 30 minutes in late May while boaters up north sat dry-docked because launching ramps remained high and dry. Are these simply short-term weather events, or do they represent long-term climate change? Dozens of Wisconsin scientists have come together to form the Wisconsin Initiative on Climate Change Impacts (WICCI), an interdisciplinary project drawing from multiple agencies and specialties. They have conducted thorough analyses of weather records collected at dozens of observation stations statewide for the past 56 years.

Their conclusion is that Wisconsin’s climate is changing. Wisconsin is becoming “less cold,” according to Chris Kucharik, UW-Madison assistant professor of agronomy and atmospheric and ocean sciences. Northern Wisconsin has become drier, but southern and western Wisconsin have become much wetter, by as much as 7 inches per year.

Water resources are changing as a reflection of these changing climate patterns, too. Long-term ice cover data on Wisconsin lakes show lakes are freezing later and breaking up earlier. Geneva Lake in southeast Wisconsin did not freeze at all during two winters in this decade, something that has never before been documented.

Groundwater and lake levels also reflect changing climatic conditions and their variability across the state. Water levels in most groundwater-dependent lakes in north-central and northeastern Wisconsin are at their lowest levels in the past 60 years. In contrast, water levels in groundwater-fed lakes in southern Wisconsin have risen. Stream flow also mirrors these historic trends—where precipitation has increased in the state, so has stream flow.

Projections show that average temperatures in the state will warm by four to nine degrees Fahrenheit by the middle of the century, yielding fewer nights below zero and more days above 90 degrees.

Precipitation is much more difficult to predict, but winter and spring precipitation is likely to increase by 20 percent. Combined with warmer temperatures, there may be less snow, and more rain and freezing rain. Higher temperatures may also lead to more spring thunderstorms and heavy rains.

All of these changes will affect Wisconsin dramatically, from the kinds of fish and plants that can live here, to crop selection and cultivation, and recrecreation choices.

Over the past year, water experts have identified likely effects of climate change on water resources. These include:

  • Increased flooding will affect infrastructure and agricultural land.
  • Harmful blue-green algae will occur more frequently with increased summer temperatures.
  • Groundwater extraction and demand for water will increase due to variable precipitation and warmer growing season temperatures.
  • Seepage (groundwater-fed) lakes will change due to variable precipitation, recharge or increased evaporation.
  • Increased sediment and nutrient loading will result from earlier and more intense spring runoff events.

Adaptation strategies to these projected impacts are being developed by WICCI’s working groups and will be shared in an assessment report to the Wisconsin Natural Resources Board in October 2010.

“WICCI is an incredible opportunity to bring together some of Wisconsin’s best scientific minds over a very important topic that will affect all of us,” said Jim Hurley, co-chair of WICCI’s water resources working group and assistant director for research and outreach at the Aquatic Sciences Center. “It’s exciting to see hydrologists, stream biologists, limnologists, wetland experts and hydrogeologists all interacting with the common goal of adapting to climate change in the state.”

See for more information.

The Aquatic Sciences Center is the administrative home of the
University of Wisconsin Sea Grant Institute & University of Wisconsin Water Resources Institute.

©2011 University of Wisconsin Board of Regents