You really are lost and cannot seem to understand what's going on in our environment today. If you know methane and CO2 cause our atmosphere to heat up and the shrinking of sea ice to cause the oceans to warm as well why are you so concerned with ice ages. Humans were not alive when CO2 was this high in our atmosphere. Methane is increasing in our atmosphere as the ground starts to melt and releases these stored gases. Ice ages don't form overnight and it is human activity that is causing the increase in CO2 and methane.