Dealing With Climate Change Will Take Gray And Green Infrastructure

When most people envision the impending disaster of climate change, it typically involves wildfires, melting glaciers and rising seas. Chicago and other cities on the Great Lakes are threatened by none of these, but that doesn’t mean they’re invulnerable to global warming.

The mid-May storms that broke over Chicago were perhaps a sign of what’s to come. More than 6 inches of rain fell in four days beginning May 14. By May 18, the Chicago River overflowed its banks, swamping several of downtown’s iconic sites. The Willis Tower’s electrical vault flooded, plunging the 110-story building into complete darkness for the first time in its 47-year history. Chicago’s new Riverwalk also flooded, forcing the pedestrian waterfront park and tourist draw to close as well.

Experts say such storms are likely to come more frequently as the Earth heats up in the years ahead. And even though local governments have for decades poured funds into new stormwater infrastructure, it’s unlikely even the many miles of new tunnels and reservoirs can handle all the severe storms ahead.

That means landlords, government officials and urban planners need to start reimagining the city’s design, not only building up the capacity of its stormwater system, so-called gray infrastructure, but adding greener infrastructure, such as rooftop gardens and permeable streets that would better absorb future rainfall.

But it isn’t clear if the wider world of commercial real estate, at least in Chicago, fully realizes how much needs to change.

When ComEd crews began restoring power to Willis on May 18, it was already the city’s wettest May ever recorded, the third in a row to set a rainfall record, according to the National Weather Service. 

“The last decade was the wettest on record for the entire U.S., but particularly for the upper Midwest,” according to Andrew Gronewold, professor of civil and environmental engineering at the University of Michigan. 

And as the globe continues to heat up due to the burning of fossil fuels, storms will grow more intense, Gronewold added. 

“This is not just a Chicago issue or a national issue; this has been documented globally.” 

Anyone who walks or runs along Chicago’s lakefront this year will notice the shrunken city beaches and Lake Michigan lapping over walkways and bike paths. Massive rainfall has helped push up the July water level to 582 feet, nearly a record high and 5 feet more than in the summer of 2012. But Gronewold said the increased heat from global warming also accelerates evaporation, so it’s possible the lake could soon sink back to where it was several years ago. 

“In Miami, it’s pretty straightforward, you need to have a plan for rising seas, but for the Great Lakes, it’s not just a story of water levels rising or water levels declining but a story of fluctuations between highs and lows,” Gronewold said. 

The elevated lake level led to beachfront erosion in North Side neighborhoods like Rogers Park and in South Shore on the South Side. The city’s downtown real estate is too high to be threatened by lake levels, he added.

Even so, heavy rains will be a problem for Chicago and other Great Lakes cities far into the future. 

“Reports suggest that we have already experienced, and will see even greater, adverse weather events including record-breaking flooding, heat and drought,” according to a statement given to Bisnow by the Metropolitan Water Reclamation District of Greater Chicago, which manages Cook County’s stormwater and wastewater. 

“Most of the floods that happen in Chicago are not from the lake; it’s from the backing up of storm systems,” said Karen Weigert, former chief sustainability officer of Chicago and now vice president of business strategy and regional operations of Slipstream, a Chicago nonprofit that helps create green energy programs. “If we have flooded buildings, it tells us we have more work to do.” 

EQ Office, which acquired Willis Tower in 2015 for $1.3B, told Bisnow it would have no comment on the flooding of its building.

The city’s challenge is one of geography, Weigert said. 

“It was essentially a wetland, and it’s flat, and we just paved it over, so water doesn’t have a place to go, it just seeks out the lowest level, and that sometimes is someone’s basement.”

“The flooding is going to get worse, although we don’t yet know how bad it’s going to be,” said BuroHappold engineering associate principal Mike Stopka, who advises the owners, tenants and managers of downtown office towers on sustainability issues. He is also board chair of the Illinois Green Alliance, a nonprofit that promotes green buildings and sustainability.

The Willis Tower flood was a warning shot, but Stopka said it won’t be enough to bring the need for flood-resilient design to the top of the industry’s to-do list.

“I don’t know anybody who is making big decisions based on that right now,” he said.

But the long-term increase of flooding risk means new projects will need better infrastructure to control water flow during and after severe storms, and that expense is catching the attention of some high up the food chain in commercial real estate.

“Further upstream, on the development side and on the investment side, some are starting to ask, ‘Am I going to pour my money into a property if it’s going to be at risk in the next 10 years?’” Stopka said.

It isn’t as if Chicago has done nothing to prepare. In the past four decades, a massive series of construction projects, most notably the MWRD’s Deep Tunnel system, also known as the Tunnel and Reservoir Plan, or TARP, added more than 100 miles of underground tunnels up to 33 feet in diameter and 300 feet below the surface, as well as a series of reservoirs meant to bolster the capacity of the original, more than 100-year-old sewer and storm systems.

New amenities such as the Riverwalk were also constructed with an eye on the future.

“The Riverwalk was designed to be flooded, but the amount of rain we got in the middle of May was more than we anticipated,” Ross Barney Architects principal and Riverwalk designer Carol Ross Barney said. 

The Illinois State Water Survey, a division of the Prairie Research Institute at the University of Illinois, forecasts bigger storms in the long term. In 1960, it considered 6 inches of rain in 24 hours to be a 100-year storm. By 2019, it considered 8.58 inches of rain in 24 hours to be a 100-year storm. 

Most of Chicago’s infrastructure, from the downtown towers, streets and stormwater systems, was constructed before the full potential impact of global warming was known, Weigert said. 

Begun in 1972, the Deep Tunnel system will be finished in 2029, when it will have the capacity to hold 17.5 billion gallons of stormwater, according to MWRD. One inch of rain means more than 16 billion gallons getting dumped across Cook County, so even several inches of rain in 24 hours can overwhelm storm systems and cause flooding. But as much of the rainwater will get absorbed into the ground and not end up in the Deep Tunnel system, it can be hard to predict when floods will occur.

“TARP was not created as a response to climate change but rather to address pollution in our waterways, including Lake Michigan, our drinking water supply, and to mitigate flooding,” MWRD said. 

“The size and scope of TARP in its ability to store water, however, has made it a critical tool in the face of increased rainfall,” MWRD added. “Without this elaborate system in place, think of all the billions of gallons of water contained in these tunnels and reservoirs that would flood our basements and streets or pollute our waterways.”

These tunnels and storm systems alone can’t solve the problem. Weigert said it will be key in the years ahead to start ridding the city of so many paved areas in favor of permeable surfaces that can absorb water, along with gardens, parks and green space.

“That could take the edge off some of this,” Weigert said. “The goal is to keep the water out of the storm system and in the ground like would have happened if we hadn’t paved over the city. At the same time, you create amenities that residents need.”  

Green infrastructure has been gaining some popularity among downtown owners. But few, if any, see it as a preventive measure against future flooding, Stopka said. What makes green infrastructure popular is its appeal for tenants.

“It’s usually seen as a way to attract tenants by making buildings more beautiful,” he said. “That’s the value proposition I’m seeing.”

Weigert is optimistic the city will be able to re-engineer itself in ways that will help control the impact of global warming and said Chicago has a history of reinvention.

“Climate change raises the stakes yet again for the city to find new ways to reinvent itself,” she said.