By Mica Rosenberg

(Reuters) - A major insurance company is accusing dozens of localities in Illinois of failing to prepare for severe rains and flooding in lawsuits that are the first in what could be a wave of litigation over who should be liable for the possible costs of climate change.

Farmers Insurance filed nine class actions last month against nearly 200 communities in the Chicago area. It is arguing that local governments should have known rising global temperatures would lead to heavier rains and did not do enough to fortify their sewers and stormwater drains.

The legal debate may center on whether an uptick in natural disasters is foreseeable or an "act of God." The cases raise the question of how city governments should manage their budgets before costly emergencies occur.

"We will see more and more cases," said Michael Gerrard, director of the Center for Climate Change Law at Columbia Law School in New York. "No one is expected to plan for the 500-year storm, but if horrible events are happening with increasing frequency, that may shift the duties."

Gerrard and other environmental law experts say the suits are the first of their kind.

Lawyers for the localities will argue government immunity protects them from prosecution, said Daniel Jasica of the State's Attorney's Office in Lake County, which is named in the Illinois state court suit.

"If these types of suits are successful - where is the money going to come from to pay the lawsuits? The taxpayers," he said. The Metropolitan Water Reclamation District of Greater Chicago, also named in the suits, declined to comment.

Several class actions accusing the Army Corps of Engineers of failing to secure levees breached during Hurricane Katrina in 2005 were mostly dismissed last year on immunity grounds.

"It's a long shot for the insurance companies, but it's not completely implausible, and if you have enough cases like this going forward it might build some helpful precedent," said Robert Verchick, who served on the Obama administration's Climate Change Adaptation Task Force.

He said insurance companies are vocal about the rising costs of global warming and want to push cities to invest in prevention as a way to avoid future lawsuits.

COSTLY ADAPTATION

Chicago says it is already spending heavily on infrastructure to adapt to changing weather and has a comprehensive Climate Action Plan.

But the city's foresight may have made it a target, said Verchick, since Farmers cites the document as evidence officials were aware of the risks.

The Chicago law firm Sneckenberg Thompson & Brody, which represents Farmers, directed questions to the insurance company. Farmers spokesman Trent Frager would not specify how much the company paid in insurance claims, and none of the suits specified a damage amount.

Flooding struck Illinois in April 2013, and the federal government paid more than 64,000 Illinois households and individuals more than $218 million in aid and low-interest loans following the storms, said the state's Emergency Management Agency.

Fear of lawsuits can be a barrier to local government action, said Alice Kaswan from the University of San Francisco School of Law. Insurers or citizens may sue them for allowing building in areas prone to flooding or wildfires. Or property owners could argue their land was devalued if a locality bars construction in high-risk areas as a precautionary measure.

Lawsuits trying to pin liability for climate change on greenhouse-gas emitters have largely failed, since it is difficult to prove an individual polluter is responsible for global phenomena such as rising sea levels.

Ultimately, costs will need to be distributed more broadly if cities and individuals want to avoid higher insurance premiums or losing coverage altogether, Kaswan said. (Reporting by Mica Rosenberg; Editing by Howard Goller and Douglas Royalty)

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