The Wall $treet Journal has an interesting subscribers-only op-ed by Jyllands-Posten culture editor Fleming Rose and Bjorn Lomborg on Al Gore's unwillingness to debate or take tough interview questions on his movie and book, An Inconvenient Truth. As Rose and Lomborg tell it, Jyllands-Posten, the Denmark's largest newspaper, had an interview scheduled with Gore to conicide with his visit to the country. The paper also planned to include Lomborg as a counterpoint in the interview, but it was not to be.

The interview had been scheduled for months. Mr. Gore's agent yesterday thought Gore-meets-Lomborg would be great. Yet an hour later, he came back to tell us that Bjorn Lomborg should be excluded from the interview because he's been very critical of Mr. Gore's message about global warming and has questioned Mr. Gore's evenhandedness. According to the agent, Mr. Gore only wanted to have questions about his book and documentary, and only asked by a reporter. These conditions were immediately accepted by Jyllands-Posten. Yet an hour later we received an email from the agent saying that the interview was now cancelled. What happened?

One can only speculate. But if we are to follow Mr. Gore's suggestions of radically changing our way of life, the costs are not trivial. If we slowly change our greenhouse gas emissions over the coming century, the U.N. actually estimates that we will live in a warmer but immensely richer world. However, the U.N. Climate Panel suggests that if we follow Al Gore's path down toward an environmentally obsessed society, it will have big consequences for the world, not least its poor. In the year 2100, Mr. Gore will have left the average person 30% poorer, and thus less able to handle many of the problems we will face, climate change or no climate change.

The article goes on to note that many of Gore specific claims are either based on extremely unlikely scenarios, or misrepresentations of the available evidence. For example, Gore shows sea-level rise scenarios far in excess of UN projections, makes claims about malaria that are contradicted by the historical record, and only discusses the health harms of higher temperatures without considering the benefits.

Al Gore is on a mission. If he has his way, we could end up choosing a future, based on dubious claims, that could cost us, according to a U.N. estimate, $553 trillion over this century. Getting answers to hard questions is not an unreasonable expectation before we take his project seriously. It is crucial that we make the right decisions posed by the challenge of global warming. These are best achieved through open debate, and we invite him to take the time to answer our questions: We are ready to interview you any time, Mr. Gore — and anywhere.

Unfortunately, Gore is not the only one running around promoting climate scenarios based upon questionable assumptions or otherwise at odds with the avaiable evidence. Another example is the infamous Stern report. For a good summary of why the Stern report does not provide an accuarate or even-handed assessment of the costs and benefits of greenhouse gas emission reductions, see this article by Robert Mendelsohn of the Yale School of Forestry and Environmental Studies. Mendelsohn points out that the problem is not just Stern's questionable approach to discounting, but also other assumptions embedded in his analysis that skew his results.

I should also add that those who claim that there is no "proof" of global warming are also engaged in a bit of sleight of hand. Of course there are uncertainties — but that hardly makes climate change different than other environmental concerns (or other subjects of scientific inquiry).

As regular VC readers already know, I believe the preponderance of scientific evidence supports the theory that human activities are producing an enhanced greenhouse effect that is altering the earth's climate, and is likely to produce significant (albeit not catastrophic) warming over the next century. In other words, I accept the basic scientific findings of the U.N. Intergovernental Panel on Climate, but remain dubious of some of the model projections, particularly those based on highly questionable assumptions about future trends in population, economic growth, and energy use.

The fact is that the vast majority of the available evidence conforms with our general understanding of the how the climate system works and how it is likely to respnd to increases in greenhouse gas concentrations. There are debates and disputes about specific questions, ranging from the extent and nature of various feedback mechanisms, the relative contribution of certain exogenous factors, and how climate changes will affect other global trends such as sea-level rise, but this does not mean climate change is a made up concern. Uncertainty is a fact of life. It is one thing to note uncertainties when the stakes are high — as they certainly are on all sides of the climate policy debate — quite another to exaggerate uncertainties when politically convenient. I genuinely fear many of the governmental policies climate fears may be used to justify, but it would be disingenuous for me to respond by denying the real threats posed by climate change. I wish more of my political or ideological "allies" felt the same way.

The issue to me is not whether human activities are affecting the climate system (it is almost certain they are). Nor is it whether there should be a policy response — I think there should be, even if it means measures that are otherwise in tension with my fairly libertarian views of government. Rather, the issues are how we assess a risk of this magnitude and how we develop policy responses when the costs of climate policy rival those of climate change itself. Neither apocalyptic environental claims, such as those put forward by Gore, nor ideologically convenient denial of the evidence, does much to advance this debate.