There are two kinds of ice ages; they are fundamentally different and therefore require different methods of mitigation: (i) Major (Milankovich-style) glaciations occur on a 100,000-year time-scale and are controlled astronomically. (ii) “Little” ice ages were discovered in ice cores; they have been occurring on an approx. 1500-yr cycle and are likely controlled by the Sun. The current cycle’s cooling phase may be imminent and calls for urgent action.
Major glaciations – on a 100,000-year time scale
I recently published an essay on how to avoid the next major ice age; there have been nearly 20 such glaciations in the past two to three million years. The coolings are rather severe: the most recent one, ending only about 12,000 years ago, covered much of North America and Europe with miles-thick continental ice sheets and led to the disappearance of barely surviving bands of Neanderthalers; they were displaced by the more adaptable Homo Sapiens.
According to the Serbian astronomer Milankovich, glaciation timing was controlled by astronomical parameters, such as oscillations with a 100,000-year period of the eccentricity of the Earth’s elliptic orbit around the Sun; oscillations with a period of 41,000 years of the Earth’s “obliquity” (inclination of the spin axis to the orbit plane, currently at around 23 degrees); and a precession of this spin axis, with a period of about 21,000 years.
While many consider the timing issue as settled, there are plenty of scientific puzzles still awaiting solutions: For example, how to explain the suddenness of de-glaciation, transiting within only centuries from a glaciation maximum into a warm Inter-glacial, like the present Holocene period.