Climate change in Wisconsin

Daniel J. Vimont is a professor of atmospheric and oceanic sciences at UW-Madison and director of the Nelson Institute Center for Climatic Research.

What is the Wisconsin Initiative on Climate Change Impacts (WICCI) and what is the purpose of this group?

The purpose of WICCI is to link science with action. WICCI is a structured conversation between scientists and people who need information to make decisions about a variety of things in the state related to climate change. That conversation is critical.

As a climate scientist, I can only contribute one piece of the puzzle. I don’t know how farmers make decisions about their land, how tribes manage their cultural resources, or how cities make policies about helping vulnerable communities deal with extreme heat.

WICCI sets up the opportunity to have those conversations, though, and together we can move toward solutions. That’s probably the most exciting thing about WICCI to me — the chance to learn more about the amazing things that people are doing to help our state come up with climate solutions.

What has been happening with the climate in Wisconsin since 2011?

We have started to see some major climatic impacts in the last 10 years. In Wisconsin we have seen the warmest and wettest decade on record. We also saw a lot of extreme rainfall events and a lot more rainfall and moisture in general — more rainfall than we necessarily expect from climate change. That being said, the increase in rainfall and moisture is certainly consistent with what we expect from climate change.

Why are we getting more rain in Wisconsin and other parts of the country are getting less?

All else being equal, a warmer climate means that the atmosphere can hold more moisture. But air also has to be moving in such a way that the moisture gets converted into rain. In the climatological average, in places where it tends to rain there is more moisture, so it rains a little bit more.

Wisconsin is situated in a region where we will likely get more precipitation, especially during the fall, winter, and spring. In summer, we’re on the border between wetter and drier, so the model consensus is for very little change.

Can you explain the idea that in Wisconsin we will see both more drought and more intense rainfall events; how does that work?

Temperature has two interesting effects. Warmer temperatures mean that the air can hold more moisture. When you’ve got the right situation for rainfall, more rain will fall as a result. On the other hand, warmer temperatures also increase the rate of evaporation from the soil and you have longer break periods between these intense precipitation events. Those longer break periods enhance the probability of agricultural and ecological droughts as well. You can have both of these things, unfortunately. You can have the worst of both worlds at the same time.

What have you been seeing as you model for the climate in Wisconsin? Are you seeing differences between regions?

What’s interesting to me is the way that climate change interacts with the regional features in our state. In general, climate change is global, and as a result warming should be pretty uniform across our state. But that warming interacts with Wisconsin’s unique geographical features to make some interesting regional changes.

For example, where we have a lot of snow, warming reduces the amount of snow cover, exposing dark ground that can now absorb more of the sun’s radiation as well. Our projections show slightly more warming in the northern parts of our state, which is consistent with this change in snow cover.

Another example is extreme heat and extreme cold. For heat, the Great Lakes have a moderating influence on extreme heat, so warming produces fewer extremely hot days near the lakes. For extreme cold, here in southern Wisconsin we only get a few days when the temperature goes below zero degrees.

However, in northern Wisconsin, that happens pretty regularly. With climate change, we will lose only a few of those really cold days in southern Wisconsin, but in northern Wisconsin, it really changes the frequency of those really cold days.

Are there differences in the rainstorms across the state?

Climate change is likely to affect our state pretty uniformly with more intense rainfall events becoming more frequent. That being said, the southwest side of the state tends to get more extreme rainfall than the northeast side of the state. The extreme, 100-year rainfall events in the southwest part of the state may be a seven-inch event, whereas the northeast part of the state is maybe a four- or five-inch event. Those differences will all get amplified with an overall increase in the impacts.

Can you talk about the level of certainty in the predictions?

There’s a variety of levels of certainty that we have. One is “will things get warmer?” The answer is yes, we are very certain of that and we have already seen it globally and in Wisconsin. The patterns show the warming happening more rapidly during winter then summer and more at night than during the day.

All of this is consistent with what models tell us, and what we expect from theories of what will happen with increased greenhouse gases in our atmosphere. So, what our models and theories are telling us is exactly what’s happening on the ground here in Wisconsin. This means that there’s really no doubt in my mind that the kind of warming we’ve seen will continue in the future.

With rainfall, we have also seen wetter winters, springs and wetter fall conditions. That’s also what the models project, and what we expect from theory. We have also seen extreme rainfall events increasing, and the models suggest that they will continue to increase. That’s another projection that we see as a likely scenario. So again, we tend to have high confidence in those kinds of changes.

To me, the concept of natural variability is also very important to understand. There is always going to be variability in the weather and these trends are put on top of those variations. We’ve tried to incorporate this variability into our projections. From year to year, Wisconsin’s temperature naturally varies from five to seven degrees, either colder or warmer than the previous year.

Those natural variations will continue around a background warming of about five degrees by the middle of this century. That means that the coldest years of the future will be warmer than the warmest years we experience now. We are already losing these really cold years and will continue to lose them in the future.

What’s the difference now globally compared to 10 years ago when the first WICCI report came out?

The widespread impacts of climate change around the world are just smacking us in the face right now. The fires, storms, heatwaves, impacts to ecosystems, loss of ice, everything are like a right hook to the face. You can’t pretend it’s a theoretical exercise anymore. I think that’s one of the big differences from 10 years ago. We are regularly seeing massive impacts.

We have known that we are committed to climate change since the 1800s. The question is how far are we willing to go? And how fast are we willing to allow the climate to change? Our actions now will make a huge difference for avoiding the worst outcomes.

Do you have hope for the future? What do you want people to know?

Oh boy. This is a tough one. My colleague Kate Marvel has started to refuse to give a message of hope. Instead, she gives a message of courage, which is a strong statement. As she says, “Courage is the resolve to do well without the assurance of a happy ending.” I think that’s where I’m at. It’s really hard to think about what climate change means to our lives.

On the one hand, we know there are going to be hard times in the future. I mean, people’s lives are already being affected, and sometimes completely upended because of climate change. On the other hand, I tell my students in my 101 class to remember that you will still fall in love in your lifetime, you will be amazed by the kindness of strangers, you will be blown away by the beauty of the world that you live in, and all of that will happen as the climate continues to change.

The views and opinions expressed in this interview are those of the authors and do not represent official policy or position of the University of Wisconsin-Madison or the Wisconsin Initiative on Climate Change Impacts.