[NAFEX] California's screwed tree crops
list at ginda.us
Fri Jul 24 09:49:08 EDT 2009
Sure, I don't want to fight about global warming today. I do want to elaborate a little on the prior post, from Richard Harrison, asserting an increase in hill hours in some warmer states.
That's not inconsistent with global warming. My understanding is that chill hours are not hours when it's really cold, but are only hours when it's sorta chilly (near or above freezing, up to 40 or 50F), when the trees are metabolically active but 'feel cold'. I gather that in very cold places the native trees don't need a lot of chill hours, since they have to come out of dormancy quickly and do their thing. It's places with long bumpy springs and late frosts where the local trees have adapted by needing a lot of chill hours.
So if global warming is linked in some areas with a longer spring, you could easily get both higher average temps and more or similar chill hours.
Also, the US is a large country with lots of climate zones, some quite chilly. Surely agricultural plantings can move north if we get even quite a lot of global warming. Concurrant disruption of rainfall patterns is a more serious agricultural threat, but I'm sure the US will continue to be able to grow food _somewhere_, however cliate change plays out.
Alan Haigh wrote:
Please members, can we refrain from another fruitless debate on global warming?
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