Climate science debate:
On the issue of what to do about global warming, Jim Manzi has been deemed a "reasonable" conservative in the debate. He accepts that it's happening and is caused by human activity. The disagreement is in what to do about it. Manzi's position is that it's not worth implementing various policies (e.g. carbon taxes) because, on net, economic activity would suffer.
This is discussed in a TNR article by Brad Plummer
Of interest is this excerpt:
Manzi bases his argument on his reading of the IPCC's 2007 Fourth Assessment Report. According to the IPCC's own estimates, he points out, a temperature rise of 4°C can be expected to reduce global GDP by about 3 percent in 2100. And on the flip side, the IPCC pegs the cost of keeping carbon concentrations in the atmosphere below a "safe" level of 450 parts per million at around 6 percent of GDP. And so, Manzi concludes, mitigation probably isn't worth it.
Here the issue is 3% loss due to global warming vs. 6% loss due to carbon-concentration-restraint policies.
But what about that other figure? A temperature rise of 4ºC.
That's 7ºF. Which means a huge change in, well, basically everything. A change in how you go about your day (much more indoors w/ air conditioning). A change in the landscape. A change in recreation (no more skiing for you!). A change in what you can eat (at least afford to eat).
But those changes do not figure in a measure of global GDP
(at least not significantly). Manzi ignores them because he is only interested in economic cost/benefit calculations.
Manzi would probably support placing ads on the face of Half Dome in Yosemite Park if the numbers worked out. The aesthetic damage has no monetary value for people like him. If the reduction in tourist dollars is offset by the ad revenue, then go ahead and do it.