Since the release of the new IPCC report on the current and future effects of climate change, climate hawks (including myself) have made the same very basic argument that we always do: Climate change looks bad, potentially very bad, and therefore we should curtail the greenhouse gas emissions which cause it.

Clive Crook writes that this is approach is somehow responsible for public skepticism of climate change:

The main reason for the disconnect between the science and the public is the gross tactical incompetence of the climate-science community, as it's called, and its political champions. Consider this latest installment of the IPCC's survey of the science. It's more carefully hedged than its predecessors — and rightly so. There are fewer specific claims about the future that the science can't fully support or that might turn out to be simply wrong...

Yet look at how U.S. Secretary of State John Kerry, for instance, responded to the new publication: "Read this report and you can't deny the reality. Unless we act dramatically and quickly, science tells us our climate and our way of life are literally in jeopardy. Denial of the science is malpractice. ... The costs of inaction are catastrophic."

The new report doesn't say any of that. The science doesn't predict a catastrophe that would threaten the American way of life. The most cost-effective responses to the risks of climate change are measured and gradual, not dramatic and quick. [Bloomberg View]

As I'll explain in detail below, Crook is completely, 100 percent wrong with his description of the new report. But his basic attitude reveals a deeper mistake which is unfortunately incredibly common.

First, the details. Crook asserts that the new WGII report is more carefully hedged and doesn't predict catastrophe — that it is less alarming than its predecessors. This is simply false. Compare this summary for policymakers to its predecessor from 2007: The new one is much more confident about its attribution of current negative effects, and if anything more blunt about future risks.

Then he all but accuses Secretary of State Kerry of lying, asserting that the IPCC doesn't predict catastrophe from unchecked climate change. To which I can only say, did he even read the report? (If past history is any guide, probably not.) Here are some handy excerpts from page 12 of the summary, all identified with high confidence:

Risk of death, injury, ill-health, or disrupted livelihoods in low-lying coastal zones... Risk of severe ill-health and disrupted livelihoods for large urban populations due to inland flooding... Systemic risks due to extreme weather events leading to breakdown of infrastructure networks and critical services such as electricity, water supply, and health and emergency services... Risk of mortality and morbidity during periods of extreme heat... Risk of food insecurity and the breakdown of food systems linked to warming, drought, flooding... Risk of loss of rural livelihoods and income due to insufficient access to drinking and irrigation water and reduced agricultural productivity... Risk of loss of marine and coastal ecosystems, biodiversity, and the ecosystem goods, functions, and services they provide for coastal livelihoods... Risk of loss of terrestrial and inland water ecosystems, biodiversity, and the ecosystem goods, functions, and services they provide…[IPCC]

I don't know what definition of catastrophe doesn't include that lot. But I'd think, at a minimum, he owes Kerry a detailed explanation as to why not. Remember Clive, page 12.

This lack of detail brings me to Crook's most serious mistake:

I take seriously the harms that man-made climate change might cause. Action does make sense: It's a question of insuring against risk. I'm for a gradually escalating carbon tax and for ample public support for other mitigation and adaptation efforts — including more nuclear power and research and development on cheap alternative fuels. But this cause isn't advanced by exaggerating what is known in order to scare people into action, nor by denouncing everybody who disagrees with such proposals as evil or idiotic. [Bloomberg View]

The striking thing about this tone of high-minded, serious moderation is that it contains no engagement with the evidence whatsoever. So if the greens are wrong about the dangers of climate change, how much warming is acceptable? Is the international consensus that two degrees Celsius is the maximum allowable wrong? If so, why?

He doesn't even begin to answer these questions.

Here's the nickel summary of the climate hawk case: According to the IPCC, to keep warming under two degrees Celsius, human society can emit roughly one trillion metric tons of carbon. As of 2011, we have emitted 531 billion tons, leaving 469 billion tons remaining to stay under the one trillion ton cap. Several years have since passed, and we are releasing roughly 10 billion metric tons per year, which is increasing — meaning on our current path we will blow through the cap by 2040.

You can dive in to the details here, but given the rough magnitudes of those numbers it is very easy to understand the case intuitively: To stay under two degrees of warming, we must sharply reduce our emissions very soon. The longer we procrastinate, the steeper the drop must be to stay under two degrees.

Even just stabilizing our emissions now and cutting them at a rate unprecedented in human history is totally inadequate. If we peak in 2015 — which, in case you've forgotten, is next year — then rich countries will probably have to cut their emissions by roughly 10 percent per year, an utterly unprecedented amount. And remember, this IPCC report barely even considers levels of warming of four degrees Celsius or higher. Studies on that kind of thing are truly the stuff of nightmares.

If you believe in the risks of climate change, as Crook claims he does, then that's the reasoning that really matters: How much greenhouse gas is being emitted, and how much we can emit overall. That leads directly, using nothing more than simple arithmetic, to a rough calculation of how fast emissions must be cut.

This is the problem with Crook's brand of High Broderist faux-moderation. Crook says he supports some kind of carbon tax and public funding for research and mitigation, but he quite obviously hasn't given the slightest thought as to whether that policy would be enough to achieve his climate goals, or even what those goals are. Instead, he just implicitly assumes that the best solution is one that doesn't disrupt the status quo very much.

Any position called "moderate" with respect to climate science would, at a minimum, engage with the evidence and predictions, which leads straightforwardly to a need for extremely aggressive action as soon as possible. But Crook's position is political moderation — that is, simply picking a point somewhere in the middle of the political spectrum.

Political moderation on climate change is many things, but perhaps the most important one is that, as we've seen, it is incredibly risky. Such a position is, in effect, courting tremendous damage to human civilization to avoid admitting that the greens might be right about something.