Before we humans came along with our Industrial Revolution and our greenhouse gases, the earth was hurtling towards an intense ice age that could have covered much of the northern hemisphere with deep ice sheets as soon as 10,000 years from now, according to a tentative new study. But that’s no reason to thank our lucky stars for global warming, says study coauthor Thomas Crowley: “We’re creating a situation at least as dangerous, only going in the opposite direction” [Wired News].
Climate data shows that complex life evolved on a much warmer “hothouse earth,” and that the planet has been gradually cooling for the last 50 million years. Then, 2.5 million years ago, the climate entered a curious new phase: it started oscillating wildly, see-sawing between interglacial periods with conditions similar to today’s and ice ages during which the amount of permanent ice in the northern hemisphere expanded hugely. At the peaks of these transient ice ages, much of northern Europe, northern Asia and North America were covered in ice sheets [more than 2 miles] thick, and sea levels were [almost 400 feet] lower than today [New Scientist]. The new study argues that this period of oscillations was a transition to a stable, long-term ice age that would have made those previous ice ages look like mere cold snaps.
After running a batch of 300-year-old Stradivarius 
The Earth was an inhospitable place 635 million years ago, when ice sheets that extended to the equator. Scientists have long wondered how the planet rebounded from that icy era, known as “Snowball Earth.”
