What changed?
Hmm. Could it be that more people are suffering from heat-related problems now, compared to the last warm period of the '30s, because the
people are different? Because a typical 2006 American encloses the volume and mass of two typical 1936 Americans?
Incidentally, the pic on the right is from a
wonderful online archive of 1910-1940 American people and buildings, the
Toledo Public Library archive. What makes it especially wonderful is the way it uses subject links, sort of like Flickr's tags. If you can't find what you want with a word search, you can tag around until you find it.
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Update: Rush just read a news story that answered the question. Yes, fat is the difference.
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I'm more puzzled about the question of power grids, and unsatisfied by the answers being given publicly. Here in Spokane, we had a two-week stretch of 90's with a couple of 100's. The local power company (for the first time) bumped its grid-load limit and requested voluntary conservation, which did the trick.
What puzzles me is that a two-week stretch of 90's with a couple days of 100 is NOT UNUSUAL. Spokane gets the same pattern every summer. The only discernable difference is that we had two consecutive days of 100 this July, while the 100's are usually more scattered.
And it's NOT a matter of more air conditioners, at least here. When I first moved to Spokane, I was amazed by the near-absence of AC. In Kansas and Oklahoma, something like 98% of homes have AC, while here it's more like 10%. Since then, I've been informally counting the coolers when I walk to the store in hot weather. This year is NOT different from any previous year; still about 10%.
I suspect there's some internal change in the way power companies function, or even some kind of sabotage going on. Heat happens in most parts of the country every year, but this is the first time we've seen such widespread grid overloads and even grid burnouts.