There have been warming periods in the earth's past. Science can read the geological record. But our current climate models cannot explain what happened. That's the conclusion of a new report on actual climate change and current levels of modelling and projections. You can read the whole report here on Nature Geoscience.
This report does NOT mean that global warming isn't happening. It does signify that our models and our expectations are based on highly flawed knowledge. THere are holes in our understanding, much we do not know.