A recent post at WUWT is titled “Needed: Accurate climate forecasts.” My opinion: the authors, Paul Driessen and David R. Legates, give us a stunning display of false and/or misleading claims.
Being mistaken about something, and therefore making false claims, is only human; in most cases we should correct, but not indict. Yet there are cases in which such behavior is genuinely culpable. When false claims come from those who really should know better, who indeed would know better if they were more interested in the truth than in pushing some agenda, ignorance becomes willful ignorance and therefore culpable. When those who really should know better make statements that are technically correct but clearly misleading, it becomes dishonesty. Is that what Driessen and Legates have done? You make the call.
Here’s some of the “evidence” they provide:
Moreover, there has been no warming since 1995, several recent winters have been among the coldest in centuries in the United Kingdom and continental Europe, the 2013-14 winter was one of the coldest and snowiest in memory for much of the United States and Canada – and the cold spell could continue.
Let’s consider these claims. In this post I’ll address #2 and #3 (I’ve often addressed #1 and will do so again in the future). First up, therefore, is the claim that “… several recent winters have been among the coldest in centuries in the United Kingdom and continental Europe, …” Is that true?
The best-known, and probably best, temperature record for the U.K. which extends back centuries is the Central England Temperature, or CET. It provides data for 355 U.K. winters, a season which I define in the standard climatological sense, December-January-February. Since the CET data are easily available as monthly data, it’s straightforward to compute the Dec-Jan-Feb average for each winter.
That still leaves open two questions. First, what does “recent” mean? In a vague sense, we all agree — but if we’re going to make claims about temperature data we need to quantify that somehow. My first instinct was that “recent” referred to the last decade, perhaps even two. To be generous, let’s go further than that and include in “recent” the last 30 years. To call “recent” what is, in this context, more than 30 years ago, I suggest would be misleading.
Second, what does “among the coldest in centuries” mean quantitatively? My first instinct was, that it should mean among the coldest 10 in the data record, or perhaps the “frigid dozen” coldest 12 in the record. But again, let’s be generous and include all winters in the coldest 10% — that amounts to 35 out of the 355 complete winters covered by the CET data.
Here is the average wintertime temperature in the CET data, and I’ll circle in blue the coldest 35, i.e. the coldest 10%:
It turns out that the number of winters in the CET record from the last 30 years, which fall into the coldest 10% of the data record, is equal to zero. This we can all agree on: that “several” — however you quantify it — does not include zero.
You might wonder, which of those winters fall into the hottest 10%? Here they are, circled in red, and I’ve also added an extra circle in blue to indicate the hottest 5 winters (click the graph for a larger, clearer view):
None of the recent winters has been “among the coldest in centuries,” but quite a few have been among the hottest in centuries. Even if you restrict “hottest” to include only the hottest of the hot, it turns out that 2 of the 5 hottest winters on record have happened in the last 30 out of 355 winters.
Now let’s consider the claim that “the 2013-14 winter was one of the coldest and snowiest in memory for much of the United States and Canada.”
I haven’t studied the data for all the states of the U.S. and provinces of Canada — nor shall I, because even if it’s true (perhaps you can understand why I don’t take Driessen and Legates’s word for it) it’s irrelevant. There are always extra-cold spots and extra-hot spots; to highlight only the extra-cold without even mentioning the extra-hot is, in my opinion, misleading. Are there areas in the U.S. or Canada which were extra hot? Here’s the average wintertime temperature for the most populous U.S. state (and one of the geographically largest), California:
The 2013-2014 winter in California wasn’t just “one of the hottest in memory,” it wasn’t just “one of the hottest on record,” it was the hottest on record.
My opinion: Driessen and Legates used a false claim (about U.K. winters) to cast doubt on global warming. They used a claim which might be technically correct but is clearly misleading (about U.S. and Canada winters) to cast doubt on global warming. They really should know better, indeed would know better if they were more interested in the truth than in pushing some agenda. And they did it all in a post highlighting the need for accuracy.
Does that amount to culpable ignorance? Dishonesty? You make the call.