The globe has warmed for about the last 10-20 thousand years depending on who you read. That was the end of the last ice age! Since then, in fits and spurts the globe has been warming. The "fits and spurts" seem to be due to the amount of radiation the sun sends us and the temperature oscillations of the oceans. For example, the period which ended in the nnineteenth century was known as the little ice age when temperatures were trending downward.