A real ice ball Earth happened some 700 million years ago. Since then there has been less extreme developments with carbon dioxide production by volcano's, by the oxidation of coal layers, leaking oil and gas etc., while it is absorbed by biological activity that produces coal layers and oil and gas. The carbon dioxide and oxygen content of the atmosphere through the ages has been estimated by geological markers. Most interesting is the development over the last 20 000 years . We can correlate the carbon dioxide content of the atmosphere with the development of the ice cover during that last ice age and also take account of the Milankovitch cycles which show the influence of the changing earth trajectory around the Sun. This shows a change rate of the carbon dioxide that is very much smaller than the current rate due to industrial fuel use. This makes it likely that the temperature will rise at a much higher rate than that at the end of the last ice age. We can expect a higher rate of temperature rise than happened at any time during the last 20 000 years.The climate will then change. Some areas will get dryer, others wetter. That will be a danger to agriculture in the short run and perhaps an advantage in the long run. I would imagine that a large part of Siberia might become valuable agricultural land after very large investment in water control, roads and railways. But before that happens we might have suffered a large famine. Also most people live near the seas and the rise of the sea level will damage a large part of of humankind's investments in cities, ports, industries etc. in the short time of several centuries.