Approx. 14,000 years ago, a large percentage of the globe was covered in ice. Estimates vary from one third to one half of the globe covered. This was the result of a several thousand year build-up. The passing of each winter/century/decade/millenium, would have seen an increase in the ice cover which, in turn, would reflect more of the sun's heat away, resulting in an ever greater rate of ice coverage This process is self perpetuating and a reasonable expectation would be that it would have continued, after all, it had, up to that point. But it didn't! It stopped. With no input from humans, the process started to reverse. Why and how?