As another snowstorm socks the East Coast, the coal industry has a message for the nation’s electricity customers: We told you so.

Signs of growing pains have abounded in the past few weeks of frigid weather, which struck a U.S. electrical grid that’s in the early stages of a long-term shift away from coal-fired power to natural gas. Wholesale electricity prices have spiked in regions such as New England, natural gas costs have surged with demand in Boston and Chicago, and power companies in Texas and Eastern states have had to urge residents to cut back. Some utilities have even been shifting, yes, back to coal.

The price spikes in the wholesale markets will take a year or two to affect people’s electric bills, and for the most part, the lights have stayed on. The outages that struck a half-million people across the South this week were caused by typical winter hazards like ice-coated tree branches.

But the coal industry and its supporters in Congress are sounding the alarm. They note that many of the older coal-fired power plants that have helped fill the gap this winter are due to shut down next year because of the Obama administration’s environmental rules.

“What happens … when that capacity is gone?” Sen. Lisa Murkowski (R-Alaska) asked this week at a gathering of utility regulators in Washington. “Maybe we won’t have cold periods like we’re seeing next year [and] we’ll be OK. But what kind of a policy is that? A hope and a prayer?”

Supporters of the environmental rules call the warnings of blackouts overblown, saying the nation is simply shedding dirty coal plants that can’t compete in the marketplace. They point out that regional groups in charge of ensuring reliable electric service can order plants to stay open if power delivery would suffer, while many states and utilities are carrying out programs to reduce how much electricity their customers need.

The debate points to a larger issue: The nation’s electric grid is set to change dramatically in the next decade, in part for reasons that have little to do with President Barack Obama’s policies. And some lawmakers, regulators and utility executives are increasingly anxious about how the the U.S. will handle the transition.

“The country is going through the most amazing transformation of its power grid in the shortest amount of time in its history — and we better do it right, or else we’re all going to look bad if there are supply disruptions,” said Philip Moeller, a board member of the Federal Energy Regulatory Commission.

The grid’s growing embrace of gas in place of coal is just part of a broader set of changes that have also made it harder for nuclear power to compete.

In one of the most significant changes, much of the country has moved since the late 1990s away from a tightly regulated power supply toward a free-market approach in which plant operators bid to sell wholesale electricity in a region. Operators of coal and nuclear plants say those markets don’t place enough value on stability and reliability, and instead base decisions on the lowest price, giving the advantage to natural gas.

At the same time, renewable power sources like wind and solar are increasing their share of the nation’s energy mix, aided by federal tax credits and Energy Department project financing.

Coal is feeling the markets’ squeeze. While traditionally the country’s cheapest major power source, coal plants are seeing their costs rise because of stricter environmental rules. That’s one reason hundreds of older coal-fired power plant units are expected to shut down for good in the next several years. Meanwhile, increasingly energy-efficient homes, office buildings and factories have depressed the country’s average power demand, dimming the incentive to build new power plants.

But this winter has been anything but average. Weather is by far the largest factor driving electricity demand, and the cold spells are putting the changing grid to the test.

Natural gas, for example, is plentiful nationally, but some regions such as New England don’t yet have enough pipeline capacity when the demand soars, creating price spikes in the wholesale markets. And as the coal industry likes to point out, gas’s price has historically taken big upswings and downswings.

Natural gas prices shot up as much as sixfold overnight in some East Coast markets during early January’s “polar vortex,” according to one FERC staff report, and wholesale electricity prices spiked along with them. Earlier this week, the commission agreed to let a major grid operator called PJM — whose territory includes Maryland, Virginia and Washington, D.C. — temporarily waive its usual wholesale price cap of $1,000 per megawatt-hour because of high gas costs.

The wholesale spikes won’t trickle down to residents and small-business owners right away because most of their power supply is covered by long-term contracts, said Bob Howatt, executive director of the Delaware Public Service Commission. Even if customers see their bills rise slightly in future years’ contracts, state regulators generally have systems in place to moderate price fluctuations for homes and businesses.

This year’s troubles aren’t necessarily the start of a trend, Howatt said. “The fact that PJM has asked for this waiver this one particular time doesn’t necessarily mean we’re going to see these prices next winter or the winter after that,” he said.

But many people have been affected this winter by a nationwide shortage of propane, a natural gas byproduct that millions of Americans use for heating. One power industry group, the Electric Reliability Coordinating Council, has blamed the shortage on the high demand for gas for electricity production. (Others have pointed out that much of the nation’s propane supply is being exported.)

Although prices for natural gas on the spot markets spiked several times over the past few weeks, the natural gas industry argues that observers are walking away with the wrong lessons.

“Experience over the last month shows us just the opposite,” America’s Natural Gas Alliance chief Marty Durbin said in an email Thursday. He noted that “despite record cold temperatures and record demand for natural gas,” gas prices on the futures markets have stayed around $5 per million BTUs — what would have been considered a low price before the fracking boom began several years ago.

“To put that in perspective, a similarly cold winter in 2000-2001 saw prices climb to $10, and a hurricane in 2008 saw spikes to $13,” Durbin wrote. “While there are customers without firm contracts that have to pay higher rates on the spot market, they are a small part of the overall equation.”

Some of those spot prices shot up to nearly $100 on the East Coast at one point last month, FERC’s staff report said.

Durbin also acknowledged that bottlenecks in the pipeline network, such as in the Northeast, need some work.

Coal supporters and some utility executives say the lesson of the harsh winter is “fuel diversity” — in other words, not shutting the door on coal or other sources.

“This year’s historically cold winter has served as a crystal ball into our future, revealing the energy cost and electric reliability threats posed by the Obama administration’s overreliance on a more narrow fuel source portfolio that excludes the use of coal,” said Laura Sheehan, senior vice president of communications for the American Coalition for Clean Coal Electricity.

The CEO of one major coal-using electricity producer, American Electric Power, told investors last month that January’s cold spell had his company running 89 percent of the coal-fired capacity that it’s set to retire in 2015.

Nuclear power is also struggling in the competitive markets for electricity. Nuclear plants supply steady power and aren’t affected by climate regulations, since they produce no greenhouse gases. But cheap gas and government-subsidized wind power have made it hard for small nuclear plants to compete.

“Right now, competitive markets are not working efficiently,” said Nuclear Energy Institute chief Marv Fertel, who says the markets need to place some value on benefits such as reliability and price stability.

“You want to value low price, but if that’s all you value, you’re just going to have short-term decisions,” he said.

Fertel said between six and 10 nuclear plants in the U.S. are vulnerable to shutting down because they aren’t making money. And without nuclear power, which accounts for more than 60 percent of the nation’s emissions-free electricity, Obama’s climate goals get increasingly difficult to achieve.

Edison Electric Institute Vice President David Owens added to the cries for a diverse fuel mix.

“We can just look at the recent cold spell seen all across the nation,” he said. “It is very, very clear to me that if we did not have coal and nuclear facilities available, we would have substantial disruption in electric service to electric consumers.”

Others say the cries of doom aren’t new.

“In the late 1970s, there were whole dystopian novels written about the inevitable collapse of reliable electricity service in the face of the unreasonable demands of environmental regulators,” said Ralph Cavanagh, co-director of the energy program at the Natural Resources Defense Council, during a conference this week of the National Association of Regulatory Utility Commissioners. “And we have gloriously proved all of that ludicrously wrong. The question is: Does the progress now have to stop?”

As one solution, the utility industry is turning to energy efficiency both to cut costs and ease times of high demand. Southern Co., for example, has instituted a $1 billion investment to shave off 1,000 megawatts of peak power demand by 2020 by investing in home upgrades and other programs for homeowners. The company has similar programs that already can meet 10 percent of its annual peak demand, said Jeff Burleson, Southern’s vice president of system planning.

But most parties — those optimistic or not — say we simply won’t know how the U.S. will manage the transition until it comes.

FERC’s Moeller, for instance, has long expressed wariness about the spate of new environmental regulations bearing down on the utility industry in the next few years. On the other hand, he says he sees little use in fighting gas’s rising role.

“I like diversity, but the market forces for gas are just so powerful that I’d rather accept its growing dominance and then deal with how to moderate price spikes,” Moeller said. “And the way to do that is to increase the storage capacity and deliverability through pipelines.”

Accelerating the development of several energy technology options simultaneously — in the hopes of driving their costs down — is one way to help avoid becoming overly dependent on a single fuel source over the long term, Energy Secretary Ernest Moniz said. The Energy Department has been pouring millions of research dollars into several areas, including nuclear, solar and fossil fuel technologies.

“I must say, I think that fuel diversity is important. I think most utilities feel that way as well, but right now, the economic proposition obviously is driving to gas,” he said earlier this month.