Wednesday, November 25, 2009

Differential diagnosis of climate change

When I was in medical school, I learned that the differential diagnosis was the cornerstone of any medical encounter. Differential diagnosis involves taking a detailed history of the patient's complaint, followed by a physical exam, to arrive at a few possible reasons for the person's symptoms. Once developed, this list of potential etiologies guides the doctor's further testing, so that there is little excuse for a shot-gun approach where every conceivable test is ordered.

Through training and practice I honed my differential diagnosis skills. I developed a risk stratification approach, where I had in mind about top 5 things that could likely underlie the patient's presentation, but also included 2-3 other possibilities that, if unaddressed promptly, could prove deadly. This list would serve as the roadmap for my investigation.

I am reminded of this approach as I read the developing story of the climate debate e-mails in the mainstream press. The manufactured magnitude of the furor is certainly good for news as entertainment. It is also prompting climate change skeptics to cry vindication. What has been missing from this coverage is the weight of the evidence that supports this as our current reality. While we can argue all we want about what our earth will look like in 50-100 years, what is clear is that the temperatures are on an overall rising trajectory, the glaciers are melting, and the green house gas emissions are accelerating. Put together, these facts beg the development of a sober differential diagnosis for what is causing this presentation. I would argue that in this list we need to include not only the most likely culprits, but also those that, if not stopped promptly, will result in irreversible and deadly changes in the near future. So, even if one is willing to ignore the broad scientific agreement with regard to the future of climate change or the likelihood that human activity is driving it, common sense of safeguarding against the worst case scenario demands we nevertheless do something about these factors.

And here is the contradiction of our human psyche. Take the mammography recommendations maelstrom and compare it to our attitude toward climate change. The outraged reactions to the new evidence-based recommendations are a reflection of our better-safe-than-sorry attitude toward a deadly disease, no matter what the cost to the individual or the society. So, why do we not adopt the same stance when it comes to climate change? Why not open our eyes to the possibility that, despite the poor judgment of the scientists involved in the e-mail scandal, there is a very real possibility that our climate is changing. Once this becomes a possibility, it matters little whether it is human activity that is driving it or just the natural order of things: the only modifiable risk factor that can affect this trajectory is human activity.

So, the debate becomes simply about two choices. First is to consider the idea of climate change honestly in the context of what we know to be the truth. Second is to keep our blinders on and continue to be condescended to by those whose financial interests would be affected by the resulting societal behavior change. The right choice is obvious.      

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