Jerry Taylor is the president of the Niskanen Center, a nonprofit think tank in Washington dedicated to the advancement of liberty and pragmatic policy solutions. The opinions expressed in this commentary are solely those of the author.

(CNN) Pope Francis' visit to the United States has triggered an energetic debate about the morality of climate change.

In his May encyclical Laudato si, the Pope argued that virtue and faith demand an immediate response to global warming. Many conservatives reply that economic growth, best delivered by free markets, has done more than anything to lift people from poverty. Because low energy prices facilitate growth, they say that responding to global warming in a way that raises energy prices will slow growth and hurt the least fortunate among us.

While much of what conservatives say is true, one does not need to be a Catholic, a socialist or a scientific alarmist to believe that we're morally required to take action on climate change. Indeed, the moral argument for liberty and free-market capitalism implies that we're required to act.

According to many conservatives, the core purpose of government is to protect rights to life, liberty and property. If greenhouse gas emissions threaten to violate those rights, then government must act against the threat.

That climate change poses risk of catastrophe is not at issue. Harvard economist Martin Weitzman calculates that, if the scientific assessment of the Intergovernmental Panel on Climate Change is correct, there is about a 10% chance that future warming will exceed 11 degrees Fahrenheit.

Climate skeptics in the science community, who don't buy IPCC narratives, believe that the chance of such catastrophic warming is lower, but concede that a great deal of uncertainty exists, so we can't know for sure.

A large number of scientists, on the other hand, believe that the IPCC understates the risks.

This is oh-so-speculative because we have never seen such high atmospheric concentrations of greenhouse gases in all of human history. The last time such high concentrations existed was during the Pliocene Epoch, some 3 million years ago. Temperatures were then about 2 to 5 degrees Fahrenheit warmer than they are today and, in part because there was no Arctic ice cap, sea levels were somewhere between 33 and 131 feet higher than at present.

Even if we take major steps now, concentrations of atmospheric greenhouse gases will continue to increase for more than a century. We are literally running an unprecedented experiment on the planet with few data points to suggest how it will all turn out.

Basic physics, however, tells us that warming will follow increases in the concentration of greenhouse gases. Even if the catastrophe scenarios of double-digit warming don't play out, we're not necessarily out of the woods. The most likely spread of future warming according to the IPCC, about 3 to 8 degrees Fahrenheit, could have catastrophic impacts as well.

Is it moral to put all of human civilization at risk like this? Conservatives say "yes," because restricting greenhouse gas emissions will harm the economy, and they believe that the economic and humanitarian costs will likely exceed the benefits. If it is moral to promote human well-being, they say, it is immoral to go down the road proposed by Pope Francis.

There are two problems with this argument.

First, given the uncertainties involved in predicting the trajectory of future warming -- and the economic response to greenhouse gas mitigation decades hence -- we simply can't know that the costs of action will exceed the benefits (or visa versa).

Second, the catastrophic climate change that we're flirting with would do vastly more harm to human well-being than would a modest increase in energy prices. And our best guess is that keeping greenhouse gas concentrations within "safe" limits (430-480 parts per million of carbon equivalent) would mean global average annual consumption growth rates of between 1.54% and 2.94% rather than between 1.6% and 3%.

Conservatives are right that the consumption losses associated with climate action are likely to harm the poor more than the wealthy. But by the same token, climate change is likely to harm the poor more than the wealthy because the poor in the developing world are heavily dependent upon the returns from natural capital and they lack the resources necessary for adaptation.

Regardless, concerns that mitigation will have a disproportionate impact on the poor could be addressed by wealth transfers. Conservatives, however, usually oppose that as well. Why?

The reason, I suspect, is that many conservatives would rather accept the risks from catastrophic climate change than the risks associated with mobilizing government to address the problem.

Because free markets are so central to wealth-creation and human well-being, conservative concerns are not unreasonable. But we need not expand government to address climate change.

All we need do is put a price tag on greenhouse gas emissions via a tax and leave market actors free to respond however they deem best. This solution harnesses capitalism, not bureaucrats, to do the job. Recycling those revenues back to the public via rebates or tax cuts elsewhere keeps government from growing as a consequence.

Moreover, a policy of "just-say-no" imposes its own risks to capitalism. If catastrophic warming comes to pass, free markets are unlikely to survive the political upheaval that would follow. Conservatives are gambling not just with the planet, but with the socioeconomic system they hold most dear.

The fact that we cannot precisely establish the risk we're taking with our children's future does not belie the fact that dice are being rolled. Pope Francis argues this poses a "basic question of justice."

In this regard, he is right, and conservatives should listen.