[cosmicray]

> deciduous tree leaves are mostly falling only in the Southern Hemisphere

Here in Florida, and due to the mild climate, certain species of Oaks will hold their leaves right up to the time they put out fresh buds in the spring. I have a large quantity that need to be raked up and mulched/burned/etc.

[Vivtek]

Here in Indiana, the same is true of oaks - so I'm pretty sure it's the oaks, not the climate.