According to Mikey, the climate went berserk in the year 1860, due to Mann-made CO2.
But looking at the Law Dome CO2 record, I am having a little trouble seeing exactly what happened in 1860 to cause the climate to lose its mind.
However, looking closer, something did happen in 1860. The Pony Express went into operation that year, and appears to have set the planet on course for unstoppable future disaster.
According to Mikey and Jimmy, the rapid warming started at 280 PPM, but can be stopped by going back to 350 PPM. This probably makes perfect sense if your head has been repeatedly banged against concrete recently.