A topic increasingly on our minds is the difficulty people have reaching sensible conclusions about the present and the future based on looking at the past, if they omit the business about looking at the past. For instance, and possibly with a deadline approaching the editor said “We’ve got to print something”, the Independent recently ran with the herd of independent minds a piece “Scientists warn of rising risk of Earth becoming irreversible ‘hothouse’”. Oh and “‘We could be entering a period of unprecedented climate change,’ scientists warn”. The scientists don’t merely say, they warn. But their words are historical as well as logical tosh. Nothing is happening today that hasn’t happened repeatedly. And what they allegedly say is also tedious recycling of scare stories we’ve been hearing for decades now. For instance “Several key parts of the Earth’s climate system appear closer to destabilising than previously believed, a new analysis finds.” How often can they tell us the situation is worse than the settled science said so we should believe the resettled science without a trace of skepticism? And how often can they tell us the destabilized climate might destabilize without acknowledging that climate has never been stable?
Obviously it’s rather hard to know whether the Earth’s climate system is close to doing anything dramatic, or nothing dramatic, including this vague ominous “destabilizing”, because you can’t run lab experiments with a bunch of Earths in exactly the current condition and try doing this and that to see which ones “destabilize”. And creating a new computer model where you make it unstable and then look astonished when it destabilizes is just proof that you don’t know from modeling. But we’re just getting started here.
What’s more awkward is this notion of the climate being “stable”. It’s strangely widespread among actual climate deniers from Al Gore to Bill McKibben who deny that things have always changed, often with dramatic suddenness. And, in this Independent piece:
“‘After a million years of oscillating between ice ages separated by warmer periods, the Earth’s climate stabilised more than 11,000 years ago, enabling agriculture and complex societies,’ said William Ripple, who led the study.”
If he really said any such thing, he should not have led the study. Because, first of all, whatever happened 11,000 years ago was not due to anything humans did. And what the Earth’s climate has done for the past million years or so, and it’s not exactly a well-kept secret, is to oscillate between glaciations and warmer interglacials all within an ice age called “the Pleistocene”, also not exactly a well-kept secret except it seems from him.
The pattern, though characteristically irregular in its regularity, has been for long glacial periods to begin gradually and end quite suddenly, punctuated by short interglacials that begin suddenly and end gradually. So it would be astounding if anything else had happened around 11,000 years ago other than yet another interglacial, and would cry out for explanation.
Indeed, if the Holocene had indeed “stabilized”, putting an end not just to thousands or hundreds of thousands but millions and hundreds of millions of years of fluctuating conditions instead of being just one more instance of same, it would be clear evidence of something deeply unnatural having happened, something again crying out for an explanation. But it didn’t.
Typically the interglacials are around 15,000 years and the brutal glaciations around 85,000 though again these are irregular regulars. So (duh) the fact that the Last Glacial Period ended more or less on schedule and the Holocene interglacial began does not mean the climate stopped “oscillating” and “stabilized”. It means it went right on doing precisely the same dynamic, irregularly regular things it’s been cycling through ever since the cycle mysteriously switched from roughly 41,000 years to 100,000 a million years ago.
You’d have to be a lackwit to point to that pattern as remarkable stability, liable to persist for the next 42 million years unless some dang fool started their car. So he did, and the paper printed it.
And another thing. There is no evidence to support the notion that the Holocene interglacial climate has been more “stable” than that of the previous “Eemian” interglacial climate. How could there be, when it featured rapid warming, the sudden cooling then warming of the “Younger Dryas”, the Holocene Climatic Optimum, the subsequent cooling then rebound into the Minoan Warm period, another cooling around the sack of Troy, the Roman Warm Period, the Dark Ages cooling, the Medieval Warm Period, the bitter Little Ice Age colder than anything since the last glaciation, then the modern warm period?
Of course, we have less detail about the Eemian because the proxies going back that far do not capture short events even if they are dramatic. But what we do know has that usual pattern of cycles atop cycles atop cycles, with sudden warmings amid slow coolings being absolutely routine.
To beat one of our favourite drums, when there’s a lot of natural variability in anything, it takes a long time series to know whether there’s been a shift in the underlying pattern. This whole business about tipping points, with which the Independent piece fairly bristles (“These include critical “tipping points” – such as the Greenland and Antarctic ice sheets, the Amazon rainforest and major ocean currents – that could shift abruptly once certain temperature limits are crossed”) is made wildly speculative and unsound by knowledge that there’ve been a great many of them in the past.
Again, not just the “Younger Dryas”. Rather, all those “Dansgaard-Oeschger Events” over the course of the past 50,000 years that we wrote of last week, where temperature suddenly shot up by as much as 10-16˚C in a couple of centuries or, in some cases, less than a century, indicate that hitting tipping points is not, for Earth’s climate, evidence that it has destabilized, but the same old same old stable instability. As is a long glacial being followed by an interglacial yet again. Indeed, to call the Holocene its own “epoch” when it’s just one more interglacial on the 100,000 instalment plan is not merely self-centred. It’s ignorant.
So what does Ripple prattle instead? Why:
“We’re now moving away from that stability and could be entering a period of unprecedented climate change.”
Yeah. Unprecedented climate change where the climate changes exactly as it has been doing for millions of years. How weird would that one be?
We actually risk moving into a period of unprecedented climate ignorance. That the media might not know what they’re talking about is hardly unprecedented. But scientists who don’t know their own field does seem weird.
