About 2000 years ago, there was a Roman Warm Period and then it got cold. About 1000 years ago, there was a Medieval Warm Period and then it got cold. That was called the Little Ice Age. It is warm now because it is supposed to be warm now. It is a natural cycle and we did not cause it.
When the oceans are warm and wet, it snows more and that bounds the upper limits of temperature and sea level. When the oceans are cold and frozen, it snows less and that bounds the lower limits of temperature and sea level.
CO2 just makes green things grow better, while using less water.