This graph shows the genus extinction intensity, i.e. the fraction of genera that are present in each interval of time but do not exist in the following interval, over the last 542 million years.
A few weeks ago we reviewed the
truth about ice ages and the anatomy of a zombie lie in the context of the 1970s Ice Age myth. The dodge is used almost solely by right-wing politicians to evade accountability for addressing climate change, the most pressing global environmental issue of our time. Two factors that make that dodge so effective is that it's draped over real science and propped up by real baby boomer memories—specifically, the role that Malinkovitch's analysis eventually played in the 1950s and '60s as modern climate scientists came to understand the subtle dynamics of Pleistocene era ice ages, and the way some major media outlets then ran with a looming ice age story featuring alarming headlines and images in the mid-'70s.
No sooner had that article published than a new and potentially fascinating study of long-term solar cycles reared its head. And, like in the '70s, it was immediately seized on by the usual suspects, again aided and abetted by a sloppy traditional media hungry for ratings:
This new claim comes from a presentation at conference by Valentina Zharkova, a mathematician and scientist at Northumbria University. To be clear, she’s not predicting a 60 percent drop in the light and heat emitted by the Sun, but a drop in magnetic activity in the Sun.
Our sun is a thing of layers. But it started out as a ball of unorganized gas about 5 billion years ago. Astrophysicists have good reason to think that medium-sized, main sequence stars like our sun become hotter and larger by roughly 5 percent to 10 percent per billion years. Meaning the sun was smaller and cooler 4.5 billion years ago when the solar system first took shape. It's a good thing for the early Earth that we had tons of volcanic activity, higher rates of large meteor impacts, and most importantly greenhouses gases like methane and carbon dioxide in the primeval atmosphere in prodigious quantities, or the planet might be frozen solid to this day.
We've also known for decades that our sun goes through a periodic cycle lasting about 11 years. It's in between those two vast extremes that we have little to go on. There could be much longer cycles, super-imposed, refining or even dwarfing the 11-year cycle. Fluctuations with periods of decades or centuries or millennia might even help explain heat waves or cooler times lasting for several human lifetimes.
A few weeks ago some researchers published one of the first reasonably well-documented, tentative studies about a credible solar model suggesting that there might indeed be such events. That work will have to be tested and debated before it graduates and joins the canon of science. But what's important to understand is, even if it does hold up and become consensus, the effect presented is extremely subtle, a mere refinement on the existing cycle. But if you read the way it was initially presented, it sounded far more significant:
A new model of the Sun's solar cycle is producing unprecedentedly accurate predictions of irregularities within the Sun's 11-year heartbeat. The model draws on dynamo effects in two layers of the Sun, one close to the surface and one deep within its convection zone. Predictions from the model suggest that solar activity will fall by 60 per cent during the 2030s to conditions last seen during the 'mini ice age' that began in 1645. ... Looking ahead to the next solar cycles, the model predicts that the pair of waves become increasingly offset during Cycle 25, which peaks in 2022. During Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch and this will cause a significant reduction in solar activity
A 60-percent drop? Holy smoking yellow dwarf stars, Batman! That sure sounds like an Ice Age is a'coming! And you better believe that political candidates and sitting politicians who seized on the 1970s Ice Age myth will welcome this newer version with open arms. Expect to hear it regurgitated in various mutated forms over the next two years at least.
What the study actually suggested was a 60-percent drop in certain types of magnetic activity in and around the sun's surface, not heat or light or radiation in general. And that part about the mini Ice Age tacked on the end there is pure guesswork. The cold spell touted by some global warming deniers several hundred years ago was mostly localized to Europe and North America, and may have had nothing to do with the sun. At best, this effect could reduce total insolation by a fraction of 1 percent and it's not clear if it even exists or would do that if it did.
Now, a drop of a fraction of a percent in incident solar light can add up over millennia. If all things were equal, it might even eventually help the Arctic and Antarctic ice caps recover from their current human-induced predicament and begin expanding one day. Sadly, all things are not equal. Humans are pumping greenhouses gases into the atmosphere at a rate that surpasses the greatest natural events known in the fossil record. If we extrapolate that rate forward just a few decades, then the levels and forcing effect of man-made greenhouse gases become comparable to the Paleocene-Eocene Thermal Event (PETM) 50 million years ago, and if it still goes on unabated, the levels and effect starts to approach the grandaddy of them all, the Permian-Triassic extinction event a quarter billion years ago. That last one killed off about 80 percent to 90 percent of all species over the course of several million years. We're on course to pull that off in a few decades, a blink of an eye compared with how long it took for nature to do it.
Recent ice ages are the result of many complex factors. Chief among them are subtle changes in the Earth's orbit, when and where in that changing orbit summer or winter occur in the northern or southern hemisphere, the position of continents, and volcanic activity. For the last several million years, that all added up to periodic ice ages: some would even go so far as to say we're actually in an Ice Age now and have been for some 10 million odd years. Although a more accurate statement would be that we're in an interglacial warm period between icy advances. But historically, the planet has been much warmer than it is today, times when there were no permanent ice at either pole lasting many tens of millions of years.
That was the planet of the dinosaurs and, before them, the mammal-like reptiles of the Permian. That was a world of warm oceans, hundreds of feet higher than they are today, dotted with tropical islands and ringed by steamy jungles and vast arid plains on a slowly shattering super-continent called Pangaea. And that's exactly where we might be headed again, at least with respect to the poles and the oceans, for the first time in quite a while, if we don't get a handle on industrial greenhouse gases. Future scientists might label our era the start of a new geologic period and extinction event: the Anthropocene.