Feb 28 2023

A Climate Debate Regarding Health Effects – Part II

Yesterday’s post was the first in an exchange about the effects of climate change on public health. Today’s post is my response.

Part II

Climate change is a critically important topic for society today, and it’s important that the public have a working knowledge of the facts, causes, effects, and potential interventions regarding climate change, so I am always happy to discuss the topic. Unfortunately, it’s a very complex topic that has been highly politicized and polarized. The science often becomes wrapped up in ideology – the best indication of this is that one’s political affiliation is the strongest predictor of the public’s opinions regarding climate change. The media, as they do in general, is happy to sensationalize the topic and often does not provide good context or background. Scientists have gotten better communicating about climate change, but not enough to override political affiliation.

My sense is the core issue is that the complexity of climate change allows everyone to cherry pick those details that fit their narrative. You can find examples to support whatever narrative you want to believe. You don’t even have to be factually incorrect (although many people certainly are), you just have to be selective in your details and interpretation. Climate change is a Rorschach test of subjective validation and confirmation bias.

I say this all because I think Scott’s narrative comes through very clearly. He contacted me asking fervently for a debate on this specific topic, the health effects of climate change. I thought this was a little odd since I have never written or expressed an opinion about this topic before. It seems he assumed what my position was based on other things I have written about climate change – that I think it’s real, it is primarily being caused by humans, and the effects are likely to be bad for the environment and human civilization. This brings up another aspect of the climate change debate, that people generally take sides and think that everyone fits relatively cleanly into the “for or against” side. Once someone thinks they have detected what side you are on, they then ascribe the entire package of views to you.

Scott makes his narrative clear:

We are daily inundated with a “climate emergency” just around the corner.  It also seems that all the experts (at least 97% anyway) are in some general agreement about the “devastating catastrophe” lurking somewhere out there. However, the official IPCC-5 report seems to be a whole lot less confident than the headlines mentioned above.

This is the “alarmist” narrative – scientists, experts, and the media are proclaiming a climate emergency when really there isn’t one. But I think Scott sets up a series of strawmen. One is very common – that the effects of climate change are imminent. This is really a distortion. We may be able to detect the earliest effects now, but really significant effects are not expected until the second half of this century and the full effects (like significant sea level rise) for centuries. What makes the situation urgent is that the CO2 we release today will have effects for decades, and may trigger tipping points that are not reversible on a human timescale. We are quickly burning through our carbon budget and have little time to change course.

Scott’s approach is to compare statements made by IPCC with the medical literature. This is fine, but you have to be fair in how you characterize the IPCC report. I think he is creating another massive strawman here, which he sort of recognizes. He lists studies showing decreases in heart disease and diabetes complications, then states:

Now, you might say “Well, that’s because knowledge and advancements in technology have increased over time leading to these decreases in adverse outcomes.” And you would be correct.

But then he takes it back by saying that the IPCC states that climate change “will exacerbate health problems”. I think this misreads the IPCC, setting up his strawman that dooms his entire line of argument. Saying that one factor will exacerbate health problems absolutely does not imply that other factors may not simultaneously alleviate those same health problems. If you smoke but also exercise and eat well, just because your overall heart risk is low does not mean smoking does not increase the risk. So Scott’s method is fatally flawed – you cannot just look at raw incidence numbers and declare there is no effect from climate change. Epidemiologists spend a lot of time figuring out how to tease different variables apart. But Scott dismisses all of this as “modeling”, which he rejects out of hand, explicitly favoring raw data, which is profoundly naive. He also dismissed data on the risks increased by climate change, again favoring raw data that mixes in many confounding variables.

Further, warnings of potential health effects are often framed as encouraging mitigating factors to offset the higher risk. This is the Y2K fallacy – because we invested in mitigating a potential Y2K event, when it did not manifest that does not mean it was never a threat.

Scotts examples would each take many words to deconstruct, so I will focus on one as illustrative of his problem. The reference he used to show there has been a decrease in global burn area provides the answer he apparently did not want to see. It says:

Agricultural expansion and intensification were primary drivers of declining fire activity.

Most burn area is in plains and savannas, and over this time many acres have been converted to agriculture, which is managed (for example with irrigation). So the amount of land vulnerable to burning has dramatically reduced, accounting for the decrease in burn area. If, however, we focus on forests, we see that there is a trend of increasing forest burn area from 2001 to 2019. Studies also show that warming increases the availability of dry fuel and extends the burn season. This is highly variable based on forest type – neither climate change nor its effects are uniform. But wildfires are generally increasing in the last few decades and this correlates with the effects of warming.

Ironically, Scott is happy to consider other variables when it suits him. He writes: “While existing diseases may be extending their geographic ranges, it is almost impossible to attribute this to climate change without including  globalization of trade routes.” So when the raw data does show an increase he will include a confounding factor to argue it’s not entirely due to climate change, but not when the confounding factor moves the data in the other direction.

Meanwhile, the most thorough literature review to date, published in Nature Climate Change, found:

The researchers discovered that climate change has aggravated 218, or 58%, of the 375 infectious diseases listed in the Global Infectious Diseases and Epidemiology Network (GIDEON), and the US Centers for Disease Control and Prevention’s National Notifiable Diseases Surveillance System. The total rises to 277 when including non-transmissible conditions, such as asthma and poisonous-snake or insect bites. The team also identified nine diseases that are diminished by climate change.

The bottom line is that Scott’s approach is poorly conceived and poorly executed, and was designed to confirm his alarmist narrative, not take a thorough or fair look at the data.

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