Storytime

I have arrived at the point where I want to use the rules and tools I described in the previous columns to see if I can write a story.

In the last entry, I created an imaginary place, Floodtown. It has been the site of recurrent floods in the last 15 years. Floodtown is a coastal community. Many of us immediately think of the seacoast, but we are on the coast of the Great Lakes. Floodtown is in the Detroit Metro Area on the Detroit River, which serves as the outflow of Lake St. Claire.

And here is our problem: How do we manage excess water in Floodtown as Earth warms?

Look around

The first action we take is to look at the surface around us. The goal at this early point is to get the lay of the land. Many aspects of geography could be described, but in this first look, we identify where there is land and where there is water. The presence of large lakes near Floodtown means, among other things, that there is an available water supply for the atmosphere.

This image from the U.S. Army Corps of Engineers shows the elevation and average lake levels from Lake Superior to the Atlantic Ocean. Click on the image to enlarge.

Another aspect of geography that helps us define the region we need to consider is a profile of the average lake level above sea level. Lakes Superior, Michigan-Huron, and Erie are all pretty close to the same. Lake Ontario, downstream of Niagara Falls, is more than 300 feet lower. With the Moses-Saunders Dam in place, Lake Ontario is extended down the St. Lawrence River. Then we have the relatively small Lakes Saint Lawrence, Saint Francis, and Saint Louis before we get to Montreal, the Gulf of Saint Lawrence, and the Atlantic.

There is a point to make here: Our biggest lever to control lake levels is the Moses-Saunders Dam, and this is not a very strong lever. The amount of water upstream of Niagara Falls is enormous compared to Lake Ontario and the Upper Saint Lawrence River.

If one sought to lower water levels and throw open the spillways on the Moses-Saunders Dam, all those small lakes downstream and in Montreal would flood. Lake Ontario levels would reduce slightly, but upstream of Niagara Falls, in Floodtown, we’d see very little change. Because of this geography and engineering, our ability to manage high lake levels by increasing water flow downstream is limited, and many bad potential outcomes arise from that action. This regional constraint shows the critical role of regional partners, regional plans, and regional strategies.

All weather is local

We always need to know about the local weather. Experts on weather and climate can provide information, but a good practice is to interview people. Some may have experienced floods; others may serve as emergency managers and mayors. Those concerned with flooding will likely mention severe spring and summer thunderstorms and massive, wet winter storms. As we develop our storylines for scenarios, we now understand we must choose some storms.

Lake effect precipitation is another notable weather feature that is hugely important in many areas east of the lakes. The lake effect is on the eastward side of the lakes because the weather is organized and predominately moves from west to east.

Next, we need to identify a vulnerability or two. Floodtown suffered massive chronic flooding from 2017-20, when lake levels were at record and near-record highs for months. This was also a time of persistent and heavy precipitation. We can analyze what happened during these events and use it to inform future events.

It’s complicated

It is now appropriate to consider the rule of complexity — there is no one thing climate change will do. Indeed, for Floodtown, a comprehensive plan would need to consider windstorms and droughts. Because of chronic flooding, it is deemed a higher risk, and we have deliberately limited ourselves to flooding to help manage complexity. If other vulnerabilities need to be evaluated, it is better to do them in a parallel exercise and then determine their importance relative to flood.

Even limiting ourselves to flooding, there are multiple ways floods occur. Each may require a different management strategy.

We manage multiple paths to flooding by writing plausible stories that serve as scenarios. A well-designed set of scenarios will span various outcomes and provide a foundation of use cases for how Floodtown needs to respond.

We require the stories to be plausible, a word open for interpretation. One aspect of plausibility comes from starting with a known vulnerability. Another element of plausibility is that our scenarios are consistent with the laws of physics. One way to do this is to think about types of weather events, often storms, that caused damage in the past. Weather systems form the way they form because they obey the laws of physics. The same types of weather events are likely to occur in the future, but with different characteristics because they occur in a climate hyped up on heat.

Let’s engage

We are now at a place to create our scenarios about flooding in Floodtown.

What we know best about climate change is that it has warmed and will continue to warm. When addressing a problem in a particular place, local stakeholders like to start by asking: What has changed? They want to know, first, what has changed for them, not a sweeping statement for the globe, the country, or even Michigan. The figure here shows the temperature change for the counties comprising Southeast Lower Michigan.

Click on the image to enlarge. (Image courtesy of Ricky Rood.)

Looking at the red line, you’ll note an upward trend starting about 1980 or 1990. This is perhaps even more noticeable if you look at the circles for the cooler years. There has been a clear upward trend since 1990, except for one year. We will return to that one colder year later in the story, but rest assured, that one year does not tell us global warming is bogus.

At this point, with the perceived increase in flooding and observed temperature trends, officials in Floodtown should be ready to discuss climate change. They may wonder if this much warming has increased flooding in the past 15 years; what will happen in another 15 years?

They are likely to be more interested in what is happening in the state and the Great Lakes Basin. They may begin to identify other vulnerabilities they face. And, of course, they are asking: How can we fix this?

If we look at temperature numbers, we see that from 1951-2020, the yearly average in the Great Lakes Basin has increased by 2.3°F. We can frame the future in a couple of ways: We can look at the temperature trend since 1990 and simply extend it another 30 years, or we can consider the guidance provided by climate models. In no case is it responsible to ignore these trends.

When we look forward, we expect that in the 2040-59 time frame, average temperatures will be 3° – 6° F warmer. If you are a planner in Floodtown and have been convinced that a warming of 2.3° F has contributed to recent increases in flooding, then another 3°- 6° F warming puts you on high alert.

I will end this entry by introducing the rule of complexity. Temperature is directional. On average, it is going up. We are, however, interested in floods. That draws our attention immediately to precipitation and, if we think a little bit more, to evaporation from the surface. We now have to think about things that are conditional.

Next: The floods are coming … and “cryin’ won’t help you, prayin’ won’t do you no good.”

(Lead image:  OPG’s RH Saunders Generating Station on the Saint Lawrence River via Wikipedia.)