The media has two bad habits that make it virtually impossible for consumers of, say, television news to get a good understanding of trends
- They highlight events in the tail ends of the normal distribution and authoritatively declare that these data points represent some sort of trend or shift in the mean
- They mistake increases in their own coverage of certain phenomenon for an increase in the frequency of the phenomenon itself.
Before I discuss the 2012 global warming version of this process, let’s take a step back to 2001 and the “Summer of the Shark.” The media hysteria began in early July, when a young boy was bitten by a shark on a beach in Florida. Subsequent attacks received breathless media coverage, up to and including near-nightly footage from TV helicopters of swimming sharks. Until the 9/11 attacks, sharks were the third biggest story of the year as measured by the time dedicated to it on the three major broadcast networks’ news shows.
Through this coverage, Americans were left with a strong impression that something unusual was happening — that an unprecedented number of shark attacks were occurring in that year, and the media dedicated endless coverage to speculation by various “experts” as to the cause of this sharp increase in attacks.
Except there was one problem — there was no sharp increase in attacks. In the year 2001, five people died in 76 shark attacks. However, just a year earlier, 12 people had died in 85 attacks. The data showed that 2001 actually was a down year for shark attacks.
This summer we have been absolutely bombarded with stories about the summer heat wave in the United States. The constant drumbeat of this coverage is being jumped on by many as evidence of catastrophic man-made global warming. The New York Times recently editorialized
The recent heat wave that has fried much of the country, ruined crops and led to heat-related deaths has again raised the question of whether this and other extreme weather events can be attributed to human-induced climate change. The answer, increasingly, is a qualified yes.
Certainly it has been hot, and many towns have set daily temperature records. But what frustrates me to no end is that this is a single data point. What matters is the trend.
Trend, you say? Doesn’t a 100-year high temperature in and of itself imply warming? Certainly not. I believe this will prove to be an exaggeration, but for a moment let’s assume that this heat wave has created the hottest June in 100 years for half the Continental US. That seems pretty extreme, right? But the Continental US is about 2.5% of the world’s land mass. Just by math, in a stochastic system with a stable mean, a land area of this size somewhere should have a 100-year high month about five times a year! One data point about one small patch of the Earth having a hot month tells us nothing about trends.
