i saw a chart that showed that the temp has gone up single digit degrees every 100k years in a rapid manner and then followed by a downward ratcheting of temp into the levels where earth experiences an ice age. What is the dynamic that causes the temp drop after a rapid rise? Do we need a serious rise in temp to prevent the next ice age? Could we prevent an ice age by building a big coal fire (read co2 increase in the atmosphere here)? Not many people could survive an ice age.