Mexico Wanderer wrote:
Oooooooo Canada was a tropical swamp in prehistoric times. That was before of course, thick glaciers covered much of the land...
...looking at the paleoclimate record timeline (going back ~ 500 million years), there were two mega-warming periods planet-wide: 1 roughly 460 million years ago; and 1 roughly 90 million years ago (the proxy data for these records is sea level rise events, and other more complex stuff like continental movement/shape tectonics).
Of course, there were ~10 hiccup warming events (relatively minor) over the same 500 million year span. If you look at what caused the most recent Earth cooling event, we could actually blame it on Mexico, 65 million years ago :B. As an enormous asteroid struck the Yucatan, largely causing the extinction of roughly 70% of all species living on this planet, and plunging Earth into a global cooling phase (Alvarez et al, 1980). We're into the bottom of the 3rd cooling event now after the Yucatan event. We're actually coming out of the 3rd cooling event (fast and furious).
Before the 65 million year ago event, there was another mass extinction/dramatic climate change 250 million years ago. This was probably the biggest cooling event the Earth has ever experienced over the past half a billion years...
I don't think that there exists enough proxy data for science to infer any strong "climate record" before half a billion years ago.