Pierre-Paul Pariseau
Remember June 2008?
Madison recorded almost 11 inches of rain that month, easily breaking the previous June record set way back in 1869. Flood damage to homes, businesses, roads, bridges and water treatment plants in southern Wisconsin totaled $766 million, making it the most costly natural disaster in Wisconsin history.
This drenching came as no surprise to Steve Vavrus, a senior scientist at the UW-Madison Center for Climatic Research and a member of the WICCI Climate Working Group. "That was not a rogue thunderstorm," he says confidently. "We will be seeing more of these in the future."
In fact, we already have.
The winter of 2007-08 buried Madison under more than 100 inches of snow, besting the previous record by 25 inches. The wettest month in recorded history for dozens of southern Wisconsin locations was August 2007.
This year, Madison slogged through its wettest March ever, and the 3.6-inch rainfall last Sept. 22 broke the all-time daily record for September.
Precipitation records are breaking like ice-heavy branches. And the question is inevitable: Is this the kind of weather we can expect from now on?
That's what Wisconsin Initiative on Climate Change Impacts (WICCI - pronounced wicky) is trying to figure out. WICCI grew out of an informational forum that the University of Wisconsin Nelson Institute for Environmental Studies presented to the State Senate Environmental Committee in 2007. The event packed the biggest lecture space in Science Hall and quickly expanded into a statewide collaboration.
The Nelson Institute, in partnership with the Wisconsin Department of Natural Resources, administers WICCI, coordinating the efforts of over 200 scientists, resource managers and stakeholders from the University of Wisconsin-Madison, other UW System schools and state agencies. They are deployed in 15 working groups, each studying a specific aspect of climate change that will affect Wisconsin.
This makes Wisconsin one of the first states to assemble a research team to look at what global change may mean in our own backyards, and WICCI is starting to churn out predictions.
Its projection is that our average annual temperature will rise by 4-9 degrees Fahrenheit over the next 40 years. At this rate, we may experience in just 100 years roughly the same amount of warming that has occurred since woolly mammoths were shivering through the last ice age 21,000 years ago.
WICCI also predicts the number of summer days where temperatures climb into the 90s will double by mid-century. The state has already warmed 1.3 degrees F over the past 60 years.
On the other hand, southern Wisconsin has not seen exceptionally scorching summers. This past July was Madison's coolest on record. So what gives?
The fact that warmer summers haven't materialized is a riddle that Vavrus acknowledges. It may explain some of the white strands in his dark brown hair.
Sitting before an oversized computer monitor that dominates his compact office on the 11th floor of the Atmospheric, Oceanic and Space Sciences Building, Vavrus studies reams of climate data. He speculates that agricultural irrigation may be staving off summer heat waves.
"We know there has been a big move toward higher crop density in the Midwest, and if those crops are irrigated, they are shedding a lot of their heat by evaporation. If you have a very wet surface, and you subject it to a day's worth of July sunshine, it won't warm up as much as a dry surface would."
Vavrus traces this year's especially nippy July to a wayward jet stream. "It was a reversal of what's typical in summer, but it's just as likely that next summer we could have the opposite pattern. Then we would see heat waves - a lot of them."
Although sweltering heat has not yet hit, our weather has been getting noticeably less cold. Nighttime low temperatures are warming faster than daytime highs, and that has stretched our growing season two weeks longer than it was just 20 years ago. As we watch the growing season expand, we are also seeing the number of days of ice cover on our lakes decrease.
In fact, the trend has spelled disaster for a once-annual Madison event. The last Kites on Ice was held in 2005. By lucky chance it was scheduled on the only day that season when the experts considered it safe to have that many people on the ice. Now some observers are predicting that Madison may soon see a winter where its lakes don't freeze over at all.
WICCI also predicts more freezing rain in the middle of winter. Currently, there is a 10% chance that what falls from the sky in February will be rain instead of snow. By mid-century, there will be a 30% chance we'll need to grab an umbrella instead of a shovel on Valentine's Day.
Whether rain or snow, it's likely to come down hard. Get ready for more extreme events like the 14-inch downpour that breached the shoreline of Lake Delton in June 2008.
"If it seems that heavy rainfalls have become more common lately, that's because they have," says Vavrus.
State precipitation records for Madison show that six of the top 10 24-hour rain events since 1879 have happened since 2000.
"Warmer temperature draws more moisture into the air, allowing the atmosphere to wring more moisture out of the air and produce heavy rainfall," Vavrus explains. "This is a disturbing picture. We have seen in the recent past what heavy rainfall can do."
In the past 15 years, Madison lakes have reached their 100-year flood level three times. We may need a new definition of 100-year flood.
Maintaining Madison-area lakes at safe levels involves walking a fine line. There is only a six-inch difference between too high and too low.
"We had trouble getting Monona and Waubesa back in the range last summer," says Ken Johnson, water leader for the Wisconsin Department of Natural Resources' South Central Region. "We have had the dams wide open, and those lakes haven't responded. We believe it's groundwater flowing into the lakes. If you look at the last 10 years, there has been a disproportionate amount of flooding. We are not prepared for this."
One way to better weather future downpours, says Johnson, is to get the extra water that ends up in Madison's lakes to go downstream as efficiently as possible. This will mean "opening up constrictions posed by railroad trestles built 100 years ago and rebuilding dams to try and move water through the lake system more rapidly."
Beyond that, Johnson says new development must have "more infiltration and less runoff. We need to be very cautious about developing areas that we know are going to run into the lakes and flood."
Jeremy Balousek, Dane County Urban Conservation Engineer, says engineers currently use federal information based on precipitation records from the 1960s to design their stormwater practices. That data is now being updated by the National Oceanic and Atmospheric Association.
"When those old precipitation tables were put together, all those computations were done by hand," he says. "Soon, we will have the computing power to design for the storms we have been seeing."
But these new calculating tools will not push the high groundwater levels back down.
Flooding isn't the only danger that can come from a rise in intense precipitation. It can also promote contamination of groundwater supplies.
Mark Borchardt, a researcher at the Marshfield Clinic Research Foundation, has been part of an ongoing study that has found viruses in some Madison wells. "Madison's water comes from a confined aquifer," he says. "Most of it is supposed to be protected by an impermeable layer, but the sanitary quality isn't as high as hydrogeologists thought."
Groundwater is subject to increased virus levels following any kind of major precipitation, including sudden snow melts. "A few years ago," says Borchardt, "I would have said the extreme precipitation would affect the lakes but couldn't possibly affect the wells. But it does affect wells, and that has been really surprising to us."
Increased runoff poses challenges for the University of Wisconsin Arboretum as well. "Restoration is always trying to hit a moving target that we don't fully understand," says Arboretum land manager Stephen Glass. "Climate change means we have to get more nimble."
The Arboretum's 4,500 acres sit at the bottom of the Lake Wingra watershed, which takes the brunt of almost half a billion gallons of stormwater runoff each year. That means a constant battle with erosion, sediments and heavy metals.
Invasive species such as buckthorn, honeysuckle and reed canary grass that threaten restored landscapes get a boost from the earlier springs. "They are going to have an increasing growing season, and that will make our job tougher," says Glass.
On the bright side, Glass notes that warmer weather has been a boon for a trial planting of southern forest species. These stands of eastern redbud, tulip poplar and flowering dogwood had been languishing in a forgotten corner of the Arboretum since the 1950s because Wisconsin winters were too harsh. But over the last decade, Glass says, "many of these have begun to reproduce and spread."
Across the board, climate change will have profound consequences for what grows here - and what doesn't. And it's not all bad news. A longer, milder growing season may benefit both farmers and gardeners.
Based on changes from 1990 to 2006, the Arbor Day Foundation has rewritten its Hardiness Zone Map. The chilly Zone 3 is gone from Wisconsin, and the warmer Zone 5 has moved in.
Ken Weston, an area apple grower, is taking advantage of conditions he has not seen in the nearly 70 years he has worked his orchard, which once belonged to his parents.
"We are growing varieties now that didn't used to grow here," he says. "I have eight-year-old Pink Ladies from New Zealand. It used to be you couldn't grow them north of the Illinois border, but we are growing them easily now."
Madison has been an officially designated Tree City, USA, for more than 20 years. How will climate change affect our urban forest?
Laura Whitmore, a spokeswoman for the Madison Parks Division, says the city is not sure what to expect. It is just completing an inventory of all city trees in coordination with Philip Townsend, a UW-Madison associate professor of forest and wildlife ecology.
Townsend surveyed Madison's tree canopy using imagery generated by NASA last July. In August he went out with the city bucket trucks to collect leaf samples from the top branches, which are now being analyzed and linked to the NASA images.
When the project is complete, Townsend says, "we will see which parts of the city forest are already under stress and therefore most susceptible to climate change. In general, urban trees tend to live hard and die young because of the urban heat island effect."
Townsend fears the longer growing season will do our urban trees more harm than good, by giving a boost to insect pests and tree diseases. Some trees, including bur oaks and maples, will do fine, while firs and spruces, which are native farther north, will not adapt well to our new climatic conditions.
The city's inventory, he says, is a good first step toward preparing the urban treescape for climate change.
"In a progressive city like Madison, urban foresters now know what they didn't know 50 years ago," he says. "You need diversity in your tree canopy."
Meanwhile, other city departments are gearing up for changing climate. The shift to warmer winters with more snow melt and freezing rain strikes Al Schumacher, Madison streets superintendent, as a recipe for road ruin: "You get potholes when moisture gets into the cracks in the pavement and freezes."
Schumacher has seen more potholes in Madison streets in the last 10 years, but he's not sure if these can be blamed on changing weather or aging infrastructure. The city is now working to improve the overall rating of its streets.
In the last several years, East Washington Avenue and Mineral Point Road have been reconstructed. Highway 113 is on the fast track through stimulus money. Gammon Road and more sections of University Avenue are also scheduled for work.
"There's a lot of money in the budget to make sure our roads get better," says Schumacher, "and that includes maintenance initiatives."
Madison moves on 1,707 lane miles of street - enough to drive from here to Las Vegas. And Schumacher feels ready to maintain that pavement no matter what the climate throws at him: "If we have additional freeze-thaw cycles, we think we will be okay."
Other consequences of climate change won't be as easy to fix as potholes. Milder winters will invite warm-weather pests and diseases northward, posing new threats to native plants and animals. We may lose species of cold-water fish and other wildlife that have always been a part of Wisconsin's sense of place. Farmers may need to contend with erosion and flooded fields at planting and harvest time.
WICCI working groups, pulled together from the UW-Madison and state Department of Natural Resources, are assessing what climate change will mean to Wisconsin's forests, agriculture, coastal communities and urban development.
"Global climate models give us a blurry picture of the future of Wisconsin," says Vavrus. "WICCI is bringing that picture into focus."
As a college student in the 1980s, Vavrus was drawn to climatology by a love of weather. Emerging environmental concerns directed his study to climate change.
"Acid rain was a big concern when I was in school," he says. "Acid rain and ozone holes are two areas where we took action and really made a difference, but those were low-hanging fruit compared with climate change."
California is the only other state attempting such targeted regional climate projections. As they say out there in earthquake country, shift happens.
Here in Wisconsin, with the reality of climate change soaking into our daily lives, we may be forced to make choices, some of them unexpected and some of them costly, as we adapt to our own homegrown variety of a shifting climate.
Changes we can expect to see
- Longer growing seasons and milder winters: With the final spring freeze occurring earlier and the first frost coming later, our growing season has already been stretched by two weeks. The good news is that less hardy plants can thrive in Madison gardens. The bad news is that plant pests and diseases discouraged by our harsh winters are starting to cross our borders. Expect to see the bean leaf beetle and the European corn borer soon, and kudzu is creeping our way.
- An altered urban forest: There'll be some pleasant surprises as the eastern redbud, tulip poplar and flowering dogwood start to thrive in our parkways, but more northern species such as spruce and fir could vanish.
- Shorter ice-fishing season: The winter when Lake Mendota fails to freeze could happen at any time. In 2001 there were only 21 days of ice cover. We may see skates and skis gathering dust in the closet.
- More freezing rain in winter: Combining increased precipitation with higher temperatures means more freezing rain - the perfect prescription for both potholes and pileups.
- Intense summer downpours: Though total annual rainfall may not increase, more extreme rainstorms, both 24-hour and multi-day, are expected - perhaps 50% to 100% more than today. This increases the potential for flooding, infrastructure damage, runoff and drinking water contamination.
- More summer scorchers: Projections show the number of days where the temperature exceeds 90 degrees F will double from an average of 12 each summer to 25 by mid-century.
