This is a second installment in this series exploring why we are sure we're right on climate change issues. In part 1 we heard from Skeptical Science authors Dikran Marsupial, Glenn Tamblyn and Ari Jokimäki. This time I'm going to take my own stab at the question, and post the thoughts of Dana Nuccitelli and Andy S.
What always strikes me as I read both pro-AGW and "skeptic" articles and science on the subject of AGW is this: Absolutism vs relative uncertainties.
On the "skeptic" side I continually read how this is a big hoax, scientists are altering data, "hiding the decline," they are in it for the money, they are perpetrating a fraud, we can't possibly know what the cause of warming is, or nothing we humans could do could possibly alter the climate. These positions range from the extreme with Lubos Motl keeping a list of scientists "who will be jailed," to the mainstream skeptics like Lindzen and Spencer who also attempt to lay out a case for fraud. This entire range of opinions on the skeptic side is absolute in the position that CO2 could not possibly have the effect climate scientists say. Across the gambit of arguments I see very little in the way of consistency. Any argument against AGW is okay and doesn't need to be internally consistent with any other argument against AGW.
On the side of science I read relative uncertainties rather than absolutes. There is a consistent, yet complex, message presented by a large body of published research. Atmospheric CO2 has radiative properties. We are dramatically increasing CO2 levels. Warming is occuring. Ice is melting. Glaciers are melting. Paleo data suggests there are feedbacks. There are uncertainties in the climate response but those uncertainties are constrained via multiple lines of evidence. The puzzle explaining AGW is well filled in, though not all the pieces are in place. It is unlikely adding the final pieces of the puzzle will change our understanding of the final picture.
To flip my own question around, I find the side that is "sure" about their position tends to be the "skeptic's" side. The more compelling argument, for me, is the relative and constrained uncertainties. Given this, there are decisions to be made. How do we take what is an overwhelming amount of evidence suggesting AGW is going to be a problem and balance that against the cost of action within the relative uncertainties?
Is there a chance that climate scientists have gotten this all wrong? Certainly. But the evidence is so overwhelming that the science is correct that it would be morally reprehensible to not take action to curb our greenhouse gas emissions.
We're not sure we're right - science is not about certainty, but rather about probabilities. Many different lines of evidence support the human-caused global warming theory, and that the Earth's surface will warm on average approximately 3°C in response to doubled atmospheric CO2. There is a chance the climate sensitivity to CO2 may be lower, but the odds of low sensitivity are slim, and it would be poor risk management if we were to ignore the high probability that our current path poses substantial risk for future generations.
Ultimately, as described so well by Greg Craven, our response does boil down to risk management. The scientific evidence clearly supports the human-caused global warming theory, and very harmful consequences are a possible (and probable) result if we continue with business-as-usual. The consequences if we choose to address that risk (by reducing greenhouse gas emissions) and the theory is wrong amount to a very small economic impact.
In short, we think we're right because the scientific evidence overwhelmingly supports our position, and reducing greenhouse gas emissions is clearly the correct risk management approach even if we're somehow wrong.
For most of my career, I have worked as an industrial scientist, either as an employee or consultant. It has been my responsibility to offer advice to employers and clients on when to go ahead, when to wait to get more data or when to drop a project. In practice, the data are usually inconclusive, often there is a real risk that the underlying technical model is wrong, and even successful outcomes have a large range of uncertainty. How do I know I’m right? I don’t. All I can do is honestly lay out all the pros and cons and use my best judgement in my recommendation.
Philosophically speaking, we can never claim perfect knowledge or certainty, especially about how events will unfold in the natural world. The best that we can do is to avoid bias, use multiple lines of evidence and to refine our ideas through discussion, criticism, testing and logic. From all my reading and attending conferences over the past few years, I am sure that climate science meets the highest standards of enquiry. It is clear beyond any reasonable doubt that our greenhouse gas emissions, mainly from fossil fuel use, are changing the atmosphere and that this will change the climate. It is going to get hotter and weirder, even if nobody knows precisely how hot, how weird or how fast the change will be.
No successful businessman can wait to make an investment decision until he has proof that all uncertainties and risks have been reduced to zero. Any delay, in the real world, means that the opportunity will go away or that someone else will seize it. Some climate skeptics claim that important decisions cannot be made until all the risks and uncertainties have been eliminated. These people obviously have never worked in a successful business.
We can’t ever know we are right. All we can do is rely on the best information we can get. Luckily, the knowledge provided by modern climate science is solid and consilient. But reliable information is only valuable if we act on it.
Posted by Rob Honeycutt on Friday, 4 May, 2012
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