The findings suggest human influences “will make the initiation of the next ice age impossible over a time period comparable to the duration of previous glacial cycles”, they wrote. Too much time without an ice age and Earth could become relatively barren and dry.
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A fundamental parameter determining what dips Earth into an ice age is the changing nature of its orbit around the Sun. If carbon emissions are not restricted, he said, they could end the million-year-long period of ice age cycles altogether. The researchers showed that even if carbon emissions are limited to the amount consistent with a 2C rise in temperatures – the internationally agreed goal – there will be enough CO2 in the atmosphere to avoid future ice ages that could have started 50,000 or 90,000 years from now.
‘The bottom line is that we are basically skipping a whole glacial cycle, which is unprecedented. “It is mind-boggling that humankind is able to interfere with a mechanism that shaped the world as we know it”.
“We wanted to understand what is really triggering glacial inception, and what we found is an amazingly simple function, which is the ratio between insolation around 65 north latitude and the Carbon dioxide content of the atmosphere”, Schellnhuber said.
Prof Andrew Watson of the University of Exeter said the study confirmed that humans had “cancelled the next ice age”. Just before each one begins there are periods of very low solar radiation in the summer.
The scientists undertook the study with a comprehensive Earth system model simultaneously conjuring up atmosphere, ocean, ice sheets and global carbon cycle.
Man-made greenhouse gas emissions have postponed the next ice age for an unusually long time, scientists say. During the last ice age which ended 12,000 years ago, the modern day northern Europe, Canada, and Siberia were blanketed with large ice sheets.
At a time of intense planetary warming, it’s odd to even contemplate a counterfactual world in which we might instead be in or heading into a glacial period, sometimes more popularly called an “ice age”.
“This is the motivation for our study”.
“Like no other force on the planet, ice ages have shaped the global environment and thereby determined the development of human civilisation”.
“For instance, we owe our fertile soil to the last ice age that also carved out today’s landscapes, leaving glaciers and rivers behind, forming fjords, moraines [soil and rock deposits] and lakes”.
And Prof Chris Rapley, from University College London, added: “This is an interesting result that provides further evidence that we have entered a new geological [Epoch] – “The Anthropocene” – in which human actions are affecting the very metabolism of the planet”. “In fact, an epoch could be ushered in which might be dubbed the Deglacial”. Ironically, the Earth has been spared from that fate by global warming, which is also warned to bring a different kind of doom to the planet.
Citation: Ganopolski, A., Winkelmann, R., Schellnhuber, H.J. The timing of past and future glacial inceptions can be explained by the Carbon dioxide concentration and the insolationCO2 relation.
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Where there certainly is luck however is the team’s suggestion that the “stars were aligned” for us as prior to the Industrial Evolution as the conditions required to meet an ice age were fractionally off from taking hold.
