"Urban heat island" was a useful lead, thanks.
Check this out:
www.agu.org/pubs/crossref/2004/2004GL019852.shtml
( Moon Girl Technologies horrendous beanbag, Sat 3 Dec 2011, 16:59, 1 reply)

Have you read it?
Or just read the abstract? If you read the whole paper, what did you find particularly convincing about it? If you didn't read it, then you need to be aware that just reading the abstract (1 paragraph summary) doesnt give you the context, the caveats, the confidence. It's really impossible to evaluate a piece of work by that alone. I could add it to my to read pile, but it would be at the bottom of a foot high pile of scientific papers. One thing I can tell at at glance though is that only 9 people have cited it in the 7 years since it was published, meaning that not many of their peers were interested in the work. And I know that modelling anthropogenic heat release in urban environments is really tricky, it's hard to have any real confidence in the results. In short, I'd be cautious about reading too much into this.
(BellaBella, Sat 3 Dec 2011, 18:26, closed)

I'd read it but you need a login to access it,
I'm often frustrated by this kind of thing.

I just thought it was interesting, I'm not going to be interviewed on the news or anything. Elsewhere I've discovered that direct heating from human energy use accounts for about 1% of global warming. So it's accepted that the effect is there, albeit "only 1%" as they put it, but how long before our energy use increases by a hundred-fold?
( Moon Girl Technologies horrendous beanbag, Sat 3 Dec 2011, 19:22, closed)