Few causes unite the conservatives of the newly elected 112th Congress as unanimously as their opposition to government action on climate change.

In September, the Center for American Progress Action Fund surveyed Republican candidates in congressional and gubernatorial races and found that nearly all disputed the scientific consensus on global warming, and none supported measures to mitigate it. For example, Robert Hurt, who won Tom Perriello's House seat in Virginia, says clean-energy legislation would fail to "do anything except harm people." The tea party's "Contract From America" calls proposed climate policies "costly new regulations that would increase unemployment, raise consumer prices, and weaken the nation's global competitiveness with virtually no impact on global temperatures." Even conservatives who once argued for action on climate change, such as as Sen. John McCain (Ariz.) and Rep. Mark Kirk (Ill.), have run for cover.

But it's conservatives who should fear climate change the most. To put it simply, if you hate big government, try global warming on for size.

Many conservatives say they oppose clean-energy policies because they want to keep government off our backs. But they have it exactly backward. Doing nothing will set our country on a course toward narrower choices for businesses and individuals, along with an expanded role for government. When catastrophe strikes - and yes, the science is quite solid that it will - it will be the feds who are left conducting triage.

My economic views are progressive, and I think government has an important role in tackling big problems. But I admire many cherished conservative values, from personal responsibility to thrift to accountability, and I worry that conservatives' lock-step posture on climate change is seriously out of step with their professed priorities. A strong defense of our national interests, rigorous cost-benefit analysis, fiscal discipline and the ability to avoid unnecessary intrusions into personal liberty will all be seriously compromised in a world marked by climate change.

In fact, far from being conservative, the Republican stance on global warming shows a stunning appetite for risk. When faced with uncertainty and the possibility of costly outcomes, smart businessmen buy insurance, reduce their downside exposure and protect their assets. When confronted with a disease outbreak of unknown proportions, front-line public health workers get busy producing vaccines, pre-positioning supplies and tracking pathogens. And when military planners assess an enemy, they get ready for a worst-case encounter.

When it comes to climate change, conservatives are doing none of this. Instead, they are recklessly betting the farm on a single, best-case scenario: That the scientific consensus about global warming will turn out to be wrong. This is bad risk management and an irresponsible way to run anything, whether a business, an economy or a planet.

The great irony is that, should their high-stakes bet prove wrong, adapting to a destabilized climate would mean a far bigger, more intrusive government than would most of the "big government" solutions to our energy problems that have been discussed so far.

Let's start with costs. The investment needed to slow carbon pollution might total from 1 to 2 percent of global GDP each year for several decades, according to a 2006 study by the British government. This spending would pay for advanced technology, better land use and modern infrastructure. The same study put the cost of inaction - including economic harm from property damage and lost crops - at 5 to 20 percent of global GDP, lasting in perpetuity, with the risk of vastly higher catastrophic damage. You tell me which option is more fiscally responsible.

But it's not this cost-benefit arithmetic that should most concern conservatives. Their real worry should be what it will take to manage the effects of climate change as they are felt across the economy over the course of our lifetimes.

The best science available suggests that without taking action to fundamentally change how we produce and use energy, we could see temperatures rise 9 to 11 degrees Fahrenheit over much of the United States by 2090. These estimates have sometimes been called high-end predictions, but the corresponding low-end forecasts assume we will rally as a country to shift course. That hasn't happened, so the worst case must become our best guess.

With temperature increases in this range, studies predict a permanent drought throughout the Southwest, much like the Dust Bowl of the 1930s, but this time stretching from Kansas to California. If you hate bailouts or want to end farm subsidies, this is a problem. Rising ocean acidity, meanwhile, will bring collapsing fisheries, catch restrictions - and unemployment checks. And rising sea levels will mean big bills as cash-strapped cities set about rebuilding infrastructure and repairing storm damage. With Americans in pain, the government will have to respond. And who will shoulder these new burdens? Future taxpayers.

This is just the beginning. If conservatives' rosy hopes prove wrong, who but the federal government will undertake the massive infrastructure projects necessary to protect high-priced real estate in Miami and Lower Manhattan from rising oceans? And what about smaller coastal cities, such as Galveston and Corpus Christi in Texas? Will it fall to FEMA or some other part of the federal government to decide who will move and when and under what circumstances? Elsewhere, with declining river flows, how will the Bureau of Reclamation go about repowering the dams of the Pacific Northwest?

And while we're busy at home, who will help Pakistan or Bangladesh in its next flood? What will the government do to secure food supplies when Russia freezes wheat exports? Without glaciers, what will become of Lima, Peru, a city dependent on melting ice for drinking water? Will we let waves of "climate refugees" cross our borders?

As the physicist and White House science director John Holdren has said: "We basically have three choices: mitigation [cutting emissions], adaptation and suffering. We're going to do some of each. The question is what the mix is going to be."

Today's conservatives would do well to start thinking more like military planners, reexamining the risks inherent in their strategy. If, instead, newly elected Republicans do nothing, they will doom us all to bigger government interventions and a large dose of suffering - a reckless choice that's anything but conservative.

Bracken Hendricks is a senior fellow at the Center for American Progress and a co-author, with Rep. Jay Inslee (D-Wash.), of "Apollo's Fire: Igniting America's Clean Energy Economy."