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Climate change has already started disrupting life in the Great Lakes region — and it's only going to get worse

As the Rock River began to rise near the riverfront village of Machesney Park, homeowner Jack Dillon assembled a crew of contractors, friends and family to shore up his two-story house.

The team fortified the perimeter with stacks of sandbags. They arranged and operated an elaborate network of nearly a dozen pumps to divert water. By Tuesday morning, after many neighboring homes had succumbed to the floodwater, Dillon tearfully recalled how strangers helped him stave off major damage.

"We had 12 people on payroll, and then we had neighbors and friends chip in. But there were people we didn’t even know," said Dillon, who noted he hadn't slept in 2 1/2 days. "One man made me cry. He had to be 70, and he came down three times to help pick up a load of bags.

"There’s a lot of bad people in the world, but there are some awful good ones," Dillon said with a shaky voice.

A powerful storm, known as a "bomb cyclone," walloped the Midwest and unleashed widespread flooding, including in northwestern Illinois, where record flooding prompted communities near the Rock River to evacuate.

A new report released Thursday by a team of Midwestern researchers suggests extreme bouts of precipitation and flooding could be the new normal in the Great Lakes region due to climate change.

Three of the top five wettest years on record in Chicago have occurred in the last decade, including last year, which ranked fourth with 49.23 inches of precipitation, according to the National Weather Service.

While the United States has seen annual precipitation climb 4 percent between 1901 and 2015, Great Lakes states have experienced a 10 percent rise over this same period, with much of the additional precipitation coming in the form of heavy rainfall.

The boosted precipitation is expected to exacerbate urban flooding and challenge aging infrastructure. Water quality will be diminished as stormwater and sewer systems are overpowered, and as fertilizer from farms is swept into waterways, possibly triggering algae blooms and bacteria. Wetter winters and springs are forecast, but summer precipitation is anticipated to fall by 5 to 15 percent for most of the Great Lakes states by 2100. Corn and soybean production are likely to decline 10 to 30 percent as saturated farm fields delay planting and crops withstand hotter, drier summers, the report says.

"A warmer atmosphere, by basic physics, holds more moisture, so it’s really not that surprising that we’ve had bizarre flooding events over the last few decades. It connects very clearly with what we expect," said Donald Wuebbles, a University of Illinois professor of atmospheric sciences and the lead author of the study commissioned by the Environmental Law and Policy Center and Chicago Council on Global Affairs.

For every 1 degree of warming, the atmosphere can hold 4 percent more water vapor that can turn into precipitation. Illinois has already warmed about 1.2 degrees statewide in the last century, and the state could warm by about 4 degrees by midcentury, said former Illinois state climatologist Jim Angel.

According to the weather service, the Rock River basin, a system that courses through southern Wisconsin and northern Illinois, has averaged about 6 inches more precipitation annually this decade — a 19 percent increase — compared with the 1950s. The river basin has also been on the receiving end of 14 inches of average annual runoff, a 75 percent increase over the same time period.

When the bomb cyclone arrived from the Gulf of Mexico, it only brought an inch of rainfall, but it combined with an existing 8-inch layer of snowpack, said Scott Lincoln, a senior service hydrologist with the weather service.

"When that (weather system) moved through, we had a big warming trend, and it melted all that snow in a two-day period," Lincoln said. "So it was basically like getting 3 to 5 inches of rainfall.

"Not only that, but the ground was still frozen in some areas, so it blocked the vast majority of water from soaking into the soil and it went straight into the river."

But this could just be the beginning.

Thursday's report said extreme precipitation could rise 10 to 40 percent in southern Wisconsin, the feeder system to many Illinois waterways.

In Machesney Park, ducks swam past mailboxes nearly at eye level. Displaced residents returned to survey their homes with chest-high waders. On a dead-end street in nearby Roscoe, flooding isolated more than a dozen houses and high school students resorted to kayaking to the mainland.

In addition to those who sustained flood damage to their homes, perhaps the greatest setback will be to Illinois farmers.

The soggy conditions will likely delay planting, again. Dillon, the Machesney Park resident, lives across the river from a plot of farmland he said has been barren for the last five years due to persistent flooding.

"You used to be able to raise corn in that field," Dillon said. "In the last five years, I don’t know if he’s had a crop in there or not. It’s always flooded. It’s too wet to plant, too wet to harvest."

The torrential rainfall and runoff has been known to wash fertilizer, animal waste and other pollutants from farm fields into waterways. It can also cause sewer systems to back up.

In either scenario, the untreated water can contain an unsafe amount of nitrogen, which can render the water dangerous for consumption. Fertilizer and sewage can also stimulate algae blooms that can degrade water quality. This, in turn, raises the costs associated with treating water, the new report says.

READ MORE: Chicago is sinking. Here’s what that means for Lake Michigan and the Midwest. »

Infrastructure improvements

While major cities have committed large amounts of money toward building infrastructure that can handle severe storms, many of their regulations are outdated. Precipitation is increasing, and in urban areas like Chicago, where 59 percent of the surface is paved, there are fewer pathways for water to drain.

“As more precipitation comes in over the spring, a lot of water treatment plants aren’t designed to deal with that additional runoff,” Wuebbles said.

Guidelines for stormwater infrastructure will need to meet a higher bar. Scientists in a federal report estimate the annual cost of retrofitting urban stormwater systems will exceed $500 million for the Midwest by the end of the century.

Earlier this month, Angel, who retired as the state climatologist in December, finished a report on precipitation trends that will update the benchmark for the design of storm sewers, retention ponds and road drainage in Illinois.

To receive state permits, many projects are built based on a calculation of a rainstorm that has a 1 percent chance of occurring in any given year. In the past 30 years, for northeastern Illinois, this estimate meant a weather system that could dump 7.58 inches of rain in 24 hours.

Now, after updated calculations, this kind of storm is estimated to deliver 8.57 inches of rain in 24 hours. New stormwater systems will have to be designed to withstand these heavier rains, such as the furious downpour that dumped nearly 8 1/2 inches on Chicago between July 22 and 23, 2011.

That deluge flooded basements and streets, and first responders had to use a boat to rescue stranded truck drivers on Interstate 57. The heavy rainfall, which set a single-day record, forced the Metropolitan Water Reclamation District to open the locks in Wilmette and at the mouth of the Chicago River downtown, releasing a mix of stormwater and raw sewage into Lake Michigan, prompting swim bans at the height of beach season.

“The bottom line is, it will increase the cost for any kind of retention pond or storm sewer, because it needs to be built bigger,” Angel said. “But the upside is that it should hopefully help protect you from the next flood. By building it to more recent records, it (should) be able to handle the kind of flooding we’ve had trouble with in Illinois.”

Environmental agenda

Howard Learner, executive director of the Environmental Law and Policy Center, said the organization intended to share Thursday’s 70-page report with Gov. J.B. Pritzker’s administration in addition to other state lawmakers in hopes of encouraging them to reduce greenhouse gases that contribute to climate change.

Learner said Midwestern states need to take the lead when it comes to mitigating the effects of climate change on the Great Lakes basin, the planet’s largest system of freshwater. However, it comes as President Donald Trump’s administration has assembled a panel to reassess and possibly counter a sweeping government analysis on climate change published in November. Trump has also recently proposed a budget that would slash funding for Great Lakes cleanup and restoration efforts by 90 percent.

“Even though he won his election in 2016 in Wisconsin, Michigan and Pennsylvania, President Trump’s budget cuts for the Great Lakes’ programs and his regulatory rollbacks, his clean water regulatory rollbacks, amount to a war on the Great Lakes,” Learner said. “While President Trump is stepping back from climate change realities, it’s imperative that our states and regions step up with realistic solutions that make a difference for our future.

On Wednesday, Pritzker toured flooded areas of Winnebago and Stephenson counties. While no deaths related to the flooding have been reported, state and local officials say nearly 200 people have been evacuated.

“These are some of the highest river levels this area has seen in more than three decades, and I commend local emergency managers, law enforcement, fire and the volunteer organizations that have come together to keep people safe and preserve property,” Pritzker said in a statement. “For downstream communities that will be impacted by flooding in the days and weeks to come, I know that many groups are already preparing to help their neighbors. While we know that rebuilding will take a lot of time and work, we are committed to being your partners for the future.”

tbriscoe@chicagotribune.com

mgreene@chicagotribune.com

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