Earth's Temperature cycle is very Stable with well defined limits
This is what regulates the temperature of the earth:
When much of the Northern Water, especially the Arctic Ocean is frozen, it doesn’t snow much around the Northern Latitudes and ice retreats, albedo decreases and the equilibrium temperature of the earth increases and Sea Ice melts, especially Arctic Sea Ice When the Sea Ice thawed and the ocean surface is wet, Ocean Effect Snow covers the Northern Latitudes and Ice Advances, albedo increases and the equilibrium temperature of the earth decreases and Arctic Sea Ice Freezes.
This cycle repeats over and over and adjusts itself to overcome any and everything that tries to unbalance the temperature of the earth. Something caused the Medieval Warm Period. This cycle came back with the Little Ice Age. Kick it and it will kick back!