Phoenix temperatures have been going up because of the urbanization. Previously vegetative surfaces were replaced by concrete buildings, and they hold the heat.
There are a number of knock-on effects of changing climate and environment that people can find hard to cope with.
People get concerned when temperatures at night get very high. With temperatures being 10 degrees higher, nightly minimums will get high as well, and people find that uncomfortable.
For me coming from England, I think that for Phoenix having so much sunshine, solar panels would be a great way to generate electricity.