All of "science" pertaining to global warming is limited to observations since the advent of thermometers to measure temperature and extrapolating from that data.

If you read journal and literary observations back into history:

1. Sea level rise during the Little Climatic Optimum [[the Viking era) show that the polar ice pack retreated much further north than it does today and that much of England which is dry land today was swampy fenland [[salt water marsh) during the 11th century

2. Hurricanes were so violent during the 17th and 18th century [[the Little Ice Age) that they created massive geographic shifts in Virginia and North Carolina. Examples are Lynnhaven Bay, Willoughby Spit, and closure of inlets into the NC sounds from the ocean.