In his latest op-ed, Bjorn Lomborg continues to play the role that suits him best: providing comfort to those who prefer not to worry about climate disruption. In it, Lomborg questions the idea that a warming climate brings more extreme weather and, more controversially, that current extreme weather – like current droughts in the US – are attributable to climate change. He’s dead wrong. His analysis reveals a sleepy, out-of-date view of science and, more worryingly (given he’s is a statistician by trade) a very naïve view of statistics.
What are Lomborg’s claims? Referring to the latest report by the IPCC, he claims extreme weather isn’t happening. Quoting that report, he assures us in a single cherry-picked sentence that the IPPC tells us not to worry:“North America, there is medium confidence that there has been an overall slight tendency toward less dryness (wetting trend with more soil moisture and runoff).” So don’t worry, there are no droughts coming. Really?What else does the IPCC say? And I quote:
– It is likely that the frequency of heavy precipitation will increase in the 21st century over many regions: [Translation: 66-100% certainty]
– It is virtually certain that increases in the frequency of warm daily temperature extremes and decreases in cold extremes will occur throughout the 21st century on a global scale. It is very likely—90 per cent to 100 per cent probability—that heat waves will increase in length, frequency, and/or intensity over most land areas.
– There is evidence, providing a basis for medium confidence, that droughts will intensify over the coming century in southern Europe and the Mediterranean region, central Europe, central North America, Central America and Mexico, northeast Brazil, and southern Africa. [Translation: 66-100% confidence].
This means floods, extreme temperatures and droughts. Exactly what Lomborg is telling us not to worry about. What on earth is going on?
First off, Lomborg is cherry-picking single sentences that appear to give us comfort. What’s happened so far – his single quote – is not as relevant as what’s coming – my quote. Also, wetter or dryer overall is not the issue – it’s about extreme weather. A drought and a flood render us .. um … neither wetter or dryer. So who cares about the average?
In addition, the IPCC clearly states what limits their confidence levels: “Confidence is limited because of definitional issues regarding how to classify and measure a drought, a lack of observational data, and the inability of models to include all the factors that influence droughts.” Translation: we argue about semantics, don’t have a lot of history, and the stuff is complicated. Yet they still claim near certainty on – you guessed it – floods, droughts, and extreme temperatures.
It’s easy to cherry-pick a single sentence from a long, technical and robust scientific analysis (like the IPPC’s latest) that makes climate change seem benign. But it’s dishonest, disingenuous, and dangerous. And for Lomborg – a statistician – to claim that the empirical data to date doesn’t warrant attribution of existing extreme weather to climate change is clearly disingenuous. He should know better. As Jim Hanson and others have pointed out, when the trend shows extreme heat records outpace extreme low records by a factor of 7:1 you are well into territory where individual events are precisely evidence for a changing climate.
We can continue to argue the fine points with sleights of hand. Or we can wake up and face the difficult truth that now stares us in the face: a storm’s coming, and we’d best mitigate its severity, and prepare for its fury.