In a recent Wall Street Journal op-ed, The Case Against Global-Warming Skepticism, California Berkeley physicist Richard A. Muller describes the results from a recent re-examination of climate records and declares the debate is finally, really, truly over.
Skepticism, Muller explains, may have been warranted before (how generous of him!), but now that the Berkeley Earth Surface Temperature Project folks have worked over the temperature data again, there’s no more cause for skepticism about whether or not the globe has warmed.
Warming Red Herring–and Five Real Questions
Muller is right about the globe warming, but his framing of the debate is a red herring: arguments over climate change are not about whether one accepts or “denies” that the climate has warmed in recent years.
In fact, as I’ve been explaining to some colleagues and friends today, the proponents of urgent action on climate change like to conflate five separate questions into one question in order to tag their opponents as being “unscientific,” “deniers,” “flat-earthers,” etc.
Here are the five key questions that Muller and any critic of so-called climate skepticism must confront:
Q1: How has the global average temperature changed in recent history?
Q2: How much of that change is attributable to human activities, and how much to a given activity?
Q3: What can we expect to happen to the climate in the future?
Q4: How will those predicted changes affect people in the future?
Q5: What should we do today in response to Q1–Q4?
Question 1: A Warmer World?
Muller and others have addressed Q1, which is the stuff of hard data, adjusting it for various discrepancies, and plotting it out. That’s real hard-science, and I agree, that’s about as real as we can hope to get with scientific thinking.
Still, expect debate over a number of points of the analysis from different quarters, including Steve McIntyre at Climate Audit. After all, the magnitude of actual/factual warming is a theory-driver about the sensitivity of greenhouse-gas forcing on climate.
For questions 2 through 5, however, you depart the realm of hard science for the Assumption Zone.
Question 2: Anthropogenic Warming
So, for question 2, you have to start making assumptions about how the climate works, and what is “natural,” and by comparing that to observations, estimate how much change you can attribute to human activity. You then need more assumptions and estimates to tell you which human activity contributes to the observed change, and how strongly.
These are not simple questions, as the drivers of the climate are many, and some of those are non-linear. Skepticism on attribution of change is reasonable.
Question 3: Future Climate Change
Question 3 is even tougher than question 2, as making projections of the future requires highly advanced computer modeling. Current computer models have very little skill at predicting future states of the climate even in the big picture, much less at regional levels and over discrete actionable time periods of say, a decade at a time.
And, as you’re trying to predict future greenhouse gas emissions, you have to start throwing economic assumptions into the models on top of the physical assumptions you threw in for question 2. I’d say skepticism at this level is obligatory if anyone has paid attention to the limitations of computer models in recent years.
Question 4: Good or Bad Consequences?
Question 4, not surprisingly, entails yet more assumptions about how humans will react to future changes in the climate at both global and regional levels. It also entails assumptions about human technological development, economic activity, the population level, advances in medicine, agriculture, transportation, and so on.
I’d say a lack of skepticism at this level is actually a sign of irrational belief in the ability to predict what can’t be predicted.
Question 5: Policy Choices
And with question 5, you inject a bunch of values on top of your assumptions, since the question of “what do do” has nothing to do with science, and everything to do with values: how much do I save for retirement, versus putting toward my car loan today? How much do I put aside for my kid’s college education versus buying them a new baseball glove today?
These are not science questions at all.
Climate activists would like to conflate five questions that are partly hard science, partly soft-science, and entirely non-scientific and suggest that they all point to one answer: the immediate reordering of civilization based on carbon controls. This may let them defame anyone who disagrees with them as a “denier” of scientific reasoning, but it is an inaccurate characterization of the arguments over climate change.
Questions 2, 3, 4, and 5 anyone?