Even in formerly low-risk areas, home insurers are raising premiums and ending coverage. The upheaval could push down home values and reverberate through the economy.

Spend enough time talking about climate change, and you’ll eventually get pulled toward this question: What would have to happen for global warming to strike most people as an urgent crisis?

There are many candidates: More extreme heat domes hitting major American cities, coupled with widespread blackouts. Extended droughts across America’s farmland, on top of the decades-long depletion of groundwater, leading to food shortages. A two-foot rise in sea levels caused by the collapse of the Thwaites glacier in Antarctica, putting entire coastal regions in the United States underwater.

Those scenarios seem a long way off to many Americans (even if they might not be). But what if the thing that will make climate change feel like a crisis to most everyone is already underway across the country? What if it’s the erosion of something entirely mundane, even a little boring, but also essential to modern life?

My colleague Mira Rojanasakul and I have spent most of this year digging into how climate shocks are hitting America’s home insurance industry. What we’ve found looks an awful lot like the early stages of a crisis.

As climate-fueled disasters get worse, home insurance is becoming a money-losing business in more of the country. Without insurance, you can’t get a mortgage; without a mortgage, most Americans can’t buy a home.

Last year, insurers lost money on homeowners coverage in 18 states, up from 12 states five years ago and eight states in 2013. Nationally, over the past decade, insurers paid out more in claims than they received in premiums, and, since 2018, more than 1.9 million home insurance contracts nationwide have been dropped.

The result is what you could call the Iowa effect: Even in formerly low-risk places like that state, insurers are raising premiums, restricting coverage or simply leaving.

It used to be impossible to know which communities around the country insurers were pulling back from.

This week, that changed. The Senate Budget Committee issued the findings from a yearlong investigation, showing where insurers are dropping customers — year by year, county by county. The result is a new way to map the growing threats of extreme weather.

“The climate crisis that is coming our way is not just about polar bears, and it’s not just about green jobs,” Senator Sheldon Whitehouse, Democrat of Rhode Island and chairman of the Senate Budget Committee, said during a hearing on Wednesday on the investigation’s findings. “It actually is coming through your mail slot, in the form of insurance cancellations, insurance nonrenewals and dramatic increases in insurance costs.”

To be sure, climate change isn’t the only thing driving insurers’ decisions. State regulation, the rising cost of construction, fraud and litigation, and even changes to the global reinsurance market all play a role.

But unlike those other factors, climate change doesn’t respond quickly to policy changes, nor is it cyclical. Disasters are going to keep getting worse.

Our reporting points to three things to watch for next:

• What will happen to home prices? Fewer prospective buyers means home values are likely to fall in areas where insurance becomes especially expensive or hard to get. But the pace of those changes is hard to predict.

• How will state governments respond? Insurance is regulated by the states, some of which have been experimenting with new ways to halt the erosion of their markets. Those interventions tend to revolve around giving concessions to insurers that stick around, including making it easier to charge higher premiums. It’s far from clear, though, if those steps will be enough.

• Will insurance complicate Donald Trump’s plan to ignore climate change? The Treasury Department under President Biden laid the groundwork to gather data about climate change’s effects on the insurance market, then backed off in the face of pressure from states and insurers, as my colleague Emily Flitter reported this year. But the incoming Trump administration could be pressured to intervene, especially since some of the highest premium increases are in states that he carried in November.

“Desperation clarifies the mind,” Mr. Whitehouse told me this week. “Once the looming danger of a true, systemic, 2008-style mortgage economic meltdown nears, then it’s time for everybody to pay attention.”

THE CLIMATE FIX

The rise of ‘climate Superfund’ laws

The problem: Extreme weather, largely driven by climate change, has left states, cities and towns across the U.S. with billions of dollars in damage.

The fix: Vermont this year passed the nation’s first climate Superfund law, which will require large fossil fuel companies to pay for climate-change driven damages caused by their emissions over a three-decade period.

State lawmakers in New York passed a similar bill this year, and several other states have considered similar measures.

Vermont is supposed to submit a report to the State Legislature by Jan. 15 detailing how feasible it would be to implement the law. The money the fossil fuel companies would pay would go toward climate adaptation efforts.

The law is intended to recover costs incurred by the state, as opposed to being punitive for fossil fuel companies, said Julie Moore, the Vermont secretary of natural resources, noting that state and local governments have to prepare for climate disruption. “This is an approach to try to secure the resources necessary for that adaptation,” Moore said.

In New York State, both chambers of the Statehouse are negotiating with Gov. Kathy Hochul’s office on possible amendments to the bill, according to a spokesperson for one of the bill’s sponsors. Hochul, a Democrat, has until the end of the year to act on the legislation.

A spokesperson for the governor’s office declined to comment on the bill.

The obstacles: The fossil fuel industry has yet to bring any legal challenges against Vermont over the new law, but officials and climate activists expect the sector will. “It’s a question of when, not if,” Moore said.

Neither the American Petroleum Institute nor the Vermont Petroleum Association responded to requests for comment on whether they intend to bring legal action.

Potential legal challenges aside, figuring out how the Superfund law will work is a tall order. The law calls on the state to determine which companies are responsible for greenhouse gas emissions and how much they’ve each contributed. One of the biggest issues related to climate change that Vermont faces is flooding, but a lot of work by scientists looking at the cost of climate change has been focused on heat, Moore said.

“As the first state out of the gate, we want to make sure we put forward the best case possible,” she said.

What’s next: California, Maryland and Massachusetts have also considered climate Superfund legislation over the last few years. Lawmakers in New Jersey introduced a related bill in September.

If other states don’t follow Vermont in enacting a climate Superfund law, some climate activists think the fossil fuel industry could have an easier time challenging the state’s policy.

A state like New York backing the idea could bring more legal firepower and resources in support of the idea, said Jamie Henn, the founder of Fossil Free Media, a climate advocacy group. — Allison Prang