In 2013, Lake Michigan reached its all-time recorded low, forcing ships to carry less cargo and leaving docks high and dry. Now, just seven years later, the lake is approaching its all-time high. Earlier this month, waters from a January 11 storm tore up the lakefront path, temporarily shut down portions of Lake Shore Drive, and forced the permanent closure of three Rogers Park beaches, which will now be covered with protective riprap.

Dan Egan, a Milwaukee Journal-Sentinel reporter and author of The Death and Life of the Great Lakes, gave a talk at the Harold Washington Library four days after that storm. He spoke about climate change’s contribution to the lake’s rapid fall and rise, and why this is particularly threatening to low-lying Chicago. This week, I spoke with Egan about that same topic in more depth.

At the Harold Washington Library, you said “the Great Lakes are uniquely vulnerable to climate change, [and] Chicago is vulnerable to a degree I don’t think other coastal cities are.” Can you explain why?

Because the disruption [of the lakeshore] isn’t just going in one direction [like the ocean]. It’s going in two directions, and it can also happen a lot faster. [The ocean] is a creep on the coasts. [Lake Michigan] is more like a whoosh.

Is that harder to prepare for?

You can blame the ocean rising on climate change, but you can’t always blame the lake rising on climate change. Historically, lakes peak in the summer and bottom out in the winter. Over time, you see these 30-year undulations, and that’s where you could get three feet above or three feet below the long-term average. We were outside that bracket during the 2013 low water event, and now we’re kissing the top end. We’re in danger of breaking the 1986 record high every week now.

Does climate change have anything to do with what we saw in Chicago a couple weekends ago?

Climate change can be the reason the lakes are low or the reason they’re high. When they’re low, [it's because] there were 13 or 14 years with really high evaporation. Even though we had above average precipitation, the evaporation was beating it out.

Then here comes the polar vortex, which was probably the result of climate change. That brings us two really, really heavy years of ice cover, which dramatically alters evaporation — tamps it down — and now we have high waters. So you can get high waters or low waters because of climate change.

You said that Chicago was built with the assumption that the lake would rise or fall by three feet, but now we could be looking at five feet in either direction. Is it possible for the city to adapt to that, since it’s built right up to the lake? Or are we going to have to retreat from the lakefront?

I don’t know what the answer is, but I think people are going to start looking at it real quickly. After years turned into decades turned into centuries, [people figured] the lake was going to stay pretty much where it was — that they were safe building right up to the edge of it.

But that’s only our perception of the edge. Maybe things do drop down and we stay within that six-foot bracket, but what if it goes to four feet above, or five? Now it’s a ten-foot swing. What do you do to engineer your way out of it?

[In 2013], when the water was low, the Chicago river was about to [start flowing] forward, back into the lake. Then there goes all that collective flush of Chicagoland right into the drinking water.

What are the other drawbacks of the lake getting lower than it’s ever been?

You could see those five years ago. Property owners want the lake to be six inches below the top of their dock. They want it to be the perfect level. Shipping is a huge problem. Drinking water. The mayors of the Great Lakes cities in 2012 and 2013 were writing the International Joint Commission, asking them to do something more because their drinking water was being threatened. If the water’s not deep enough, it’s prone to having more bacteria in it.

I’ve heard that climate change means we’re going to have higher highs and lower lows.

That’s a reasonable assumption.

Did you see the damage to the lakefront path in Chicago, and water getting onto Lake Shore Drive? Are those going to be viable paths and roadways, or is the lake going to swamp them?

Who knows? It doesn’t take a hydrologist to look at what happened two weeks ago and think, “What happens if we get another foot, and get hammered with floods and then it freezes?”

The shoreline is vulnerable to erosion. Think about in the Door Peninsula, all these big concrete docks that are underwater. This dock that I grew up goofing around on at my grandmother’s house in Egg Harbor is now an inch underwater. Five or six years ago, we were up there in the winter, and one of my kids crawled through a culvert. That culvert is now six feet underwater, and if it ices up good, it's going to [expand] and tear it up.

Over the years, Chicago built its shoreline outward into Lake Michigan using thousands of acres of landfill. Would we still have these problems if we had our original, natural shoreline?

I think the problems would be worse. Chicago was kind of a sag. It was lowland. It was built up — that's why Chicago is where it is. It doesn’t take a lot of imagination to put three more feet of water into that lake. Just think: we’ve been up six feet since 2013. What if we went up six feet from 2020?

Then all the lakefront streets are underwater.

It would seem. But they already were when the storm came in a couple weeks ago.

Could we end up back down six feet, if we don’t have a polar vortex and we go back to the evaporation we were having?

It could go down further than that. At five feet above the long-term average, we armor the coast, then all of a sudden it shrinks back ten feet. That riprap at Howard Beach, what’s that going to look like if the lake goes down? Do you go in and pull it out?

What’s happening in Milwaukee and other Great Lakes cities?

The swimming beach that I take my kids to is gone.

Do you see any changes in future design of lakefront property or beaches to account for this?

You would build farther back. It’s a moving target.

We ran a story a couple years ago about how Chicago is going to be a winner in the era of climate change, because we have the water and we have milder temperatures. But it turns out nobody is safe.

Chicago, too, seems to be uniquely vulnerable, because it’s so flat. There aren’t bluffs. In Milwaukee, there’s very little housing that’s right on the water. I live three blocks from Lake Michigan, but probably 80 feet above it. Chicago is just a sag between the [Lake Michigan and Mississippi] basins.

The very thing that made Chicago a great city is turning out to be a disadvantage.

Those waters like each other, the Mississippi and Lake Michigan.