Chapter 8.6 in last summer’s US Department of Energy Red Team Climate Report looks at one of the favourite themes of the ambulance-chasing squad of the alarmist movement: Extreme Event Attribution, aka EEA which apparently stands for Effortless Egregious Accusations. They begin by noting what we discussed last week, that even after defining the term as broadly as possible the IPCC could not connect most climate impacts to greenhouse gases. Yet in another chapter they claim the opposite, that evidence for attribution is strengthening. The ambiguity reflects the different perspectives of different teams, and also that the underlying scientific literature is rather new and untested.
The outfit that has made EEA a global media sensation is World Weather Attribution (WWA), which we have mentioned frequently and not in a good way. The DoE report notes the role they play, and the fact that their critics have begun pointing out problems with their work, such as their overt interest in promoting climate litigation, frequent promotion of non-peer-reviewed findings and lingering doubts about their methods.
One of the doubts concerns the lack of data. EEA studies typically use records only back to 1950. But as the DoE group showed in Chapter 6, extending the analysis back to the 1800s can reveal a very different picture, namely that events that appear rare in the modern record were as or more common in the past.
They also point out that when scientists select the data to analyze based on an extreme event having just occurred, they need to ask whether it was a rare event under ordinary conditions or an ordinary event under rare conditions. In other words, weather systems can switch between different regimes, an obvious example being a hurricane in summer. Under sunny skies an 80 mile per hour gust would be a rare, extreme event, but under hurricane conditions it would be on the mild end. But if the data only consists of a single extreme event at the end of the sample, statistical analysis can’t tell you what model to use.
Another implication of the lack of data is that different statistical models with very different implications can fit the data equally well. And again, when scientists pick a location to analyze based on an extreme event having just occurred there, the results stand a good chance of being biased even if they omit the extreme event itself.
The section then provides a close look at the Pacific Northwest heat wave of June 2021. The WWA ghouls swept in rapidly afterwards and concluded it was “virtually impossible” without human-caused climate change, and has become 150 times more likely due to global warming. The “red team” authors note:
“But an important counter to the first claim is that other researchers concluded from historical weather data that while a heat wave of the magnitude observed was indeed virtually impossible without anthropogenic climate change, it was also virtually impossible with climate change.”
They then quote from an assessment by the State of Oregon which pointed out that
“There is no evidence that the highly unusual combination of weather features that drove the heat dome were made more likely by climate change, and climate models do not project an increase in the frequency of high-pressure ridges over the Pacific Northwest”
The meteorology literature explained the heatwave as the result of an intense high pressure ridge hitting at a time when soils were already dry due to a lack of precipitation. Several studies argued that greenhouse gases might have increased the maximum temperature by 1 or 2 degrees C compared to the 1800s, but the heatwave itself was just bad luck.
But that sort of conclusion doesn’t make for scary headlines, so you weren’t told, until now anyway.
Coming next: climate change and agriculture.
