The New Scientist is an interesting magazine, but it’s been in the pocket of the global-warming alarmists for as long as I can remember. Now, not content to point the finger at modern industrial society (for a problem that doesn’t exist), they argue that ancient hunter-gatherers in North America brought on global cooling by wiping out woolly mammoths.
You see, the only things keeping us from freezing were their mammoth farts:
When hunters arrived in North America and drove mammoths and other large mammals to extinction, the methane balance of the atmosphere could have changed as a result, triggering the global cool spell that followed. The large grazing animals would have produced copious amounts of methane, a potent greenhouse gas, from their digestive systems. They vanished about 13,000 years ago.
Felisa Smith at the University of New Mexico in Albuquerque has calculated that when these animals were around they would have emitted 9.6 megatonnes of methane annually. Ice core records show atmospheric methane levels plunged from about 700 parts per billion to just 500 ppb at the time of their extinction. Disappearance of methane emissions from the extinct species is a possible cause, Smith says (Nature Geoscience, DOI: 10.1038/ngeo877).
“It is conceivable that this drop in methane contributed to the Younger Dryas cooling episode,” says Smith. This would mean humans have been changing global climate since well before the dawn of civilisation.
Note the equivocations used to reach the conclusion: “could have,” “calculated,” “possible,” and “conceivable.” All guesswork and estimates used to make the reader think it’s not just possible, but probable that man adversely changed his climate through his foolishness – with implications for the modern day, of course. Bear in mind, no one was around to accurately measure mammoth flatulence, nor even the population of the mammoths, themselves. So Ms. Smith’s estimate of the methane output is based on assumptions, ever subject to error.
More importantly, to assume that, because the temperature drop followed the disappearance of the mammoths, the two must be related by cause and effect is to make the logical error of post hoc ergo propter hoc, “because B comes after A, A must have caused B.” It’s possible also that dropping temperatures combined with the slaughter wrought by early North Americans lead to the demise of the mammoths, as opposed to the other way round. Perhaps even an outside factor was responsible for the temperature drop, and the mammoths had nothing to do with it. Who knows?
The point isn’t to pick on Ms. Smith, who, we can assume, is a competent researcher simply positing a theory based on the results of her study. Instead, the problem lies with the journalist’s presentation, which is slanted in a way to influence the reader to think this is the most likely and reasonable explanation – and by extension toward acceptance of the theory of modern anthropogenic global warming. No criticism of Ms. Smith’s thesis is offered, nor any alternate explanation for the Younger Dryas cooling.
That’s not journalism. That’s advocacy.