stadials and glacials

Listening to a really engrossing panel discussion of geologic ice ages and the usual state of affairs of the planet Earth—how the drama has gone on for æons without of intervention or influence and what level of detail can be teased from the rock and sediment of how the inaccessible past looked, I felt a little sad that although those taking part in the discussion saw no need for some moralising postscript because it still felt rather grubby and contrarian to be talking about the topic, though strictly in the framework of billions of years and the science of geology, without addressing the weather—and made one feel like a climate-change denier. People tend to shy away from taking about vaccines, evolution or the politics of race, irrespective of the setting, to avoid controversy and being tagged with such a label and science suffers, as does the way such things are debated and understood in the public sphere.
The language of academics seems almost more relaxed than the choice words of journalists and pundits, and I was delighted to be instructed. For the past fifty million years or so to the present day, the Earth has been experiencing an ice age, by the definition that there is permanent ice at one or both poles, and the Earth has been making the transition from Icehouse to Greenhouse conditions for all its history. Though the intensity of the cycles have varied and have gotten somewhat less extreme out of consideration for the living organisms there to witness these shifts (and the Earth has been mostly a hot-house—with only some fifteen percent of the geological record attesting to a colder climate), researchers believe that it’s the cusps of these changes that drive evolutionary development, the emergence of the creatures that would become us corresponds with switch that began about fifty million. The imbalance of climatic change—or the reason there are such variations in the first place, has to do with geography driven by tectonic shift: without a landmass near or at the top or the bottom of the world there is no polar ice and oceanic currents also play a big role, like the blockage of the Isthmus of Panama or the massive southern sea that encircles Antarctica that keeps warmer water at bay. Whereas Icehouse Earth has presented in the distant itself more like icy Europa and Greenhouse Earth has been a far more watery and steamy place, the carbon-dioxide that human industry and occupation has released into the shrinking wilds has pushed our greenhouse gases beyond the levels that Nature can tolerate in an Ice Age—as my sanctimonious coda. I wonder how the New North will fare?