I'm satisfied with the Many-headed Talos explanation of why Cyrodiil is no longer a jungle, but I always assumed that it was more imperial propaganda concerning the divinity of Tiber, when in reality it is merely the end result of four hundred or so years of deforestation. After all, "jungle" only implies tropics, it doesn't necessarily mean jungle in the conventional sense.
Webster defines jungle as thus:
" Jungle - (jun' gul) - noun - from the sanskrit 'jangala' (meaning wasteland) - land densely covered with trees"
Assuming it rained a lot in Cyrodiil at the time (which is quite possible) and Cyrodiil was covered with temperate hardwoods, it would classify as a jungle, even though it was temperate. If the trees were cut down, erosion would occur, resulting in less standing water, which would slow the water cycle, and the rain would cease. More believeable than the "Many-headed Talos" explanation. However, the concept of suspended-disbelief should apply implicitly to the game, so the "official" explanation stands, regardless. I know it doesn't sound likely, but this is fantasy. None if it is likely.
Anyway. That's my two cents. Anybody got change for a 20?