I don't know whether or not one can wish another "Happy Earth Day." It really isn't that sort of holiday. It's more like Patriots' Day (19 April), a time to reflect on ideas, facts, and responsibilities.
The Industrial Revolution yielded rapid and immense gains in human standard of living. In the rush to attain these gains, our legal institutions did not keep pace, did not adapt to take into account the spillover harms (negative externalities) associated with these novel activities. Man was surely more prosperous but was at the same time fouling his nest, to his immediate and long-term detriment.
Things have gotten quite a bit better since the first Earth Day. The U.S. and several other countries with acid rain problems have brought matters under control with cap-and-trade systems. Once-moribund waterways have come back to life. The U.S. passed a Clean Air Act and established an EPA--there is room for improvement of both, but they're a start. Common-law "Environmental Justice" continues to yield results in the courts. Ozone layer thinning and a southern-hemisphere "ozone hole" was found and we are well on our way to mitigation thanks to surprisingly effective international cooperation through the Montreal Protocol. I could go on.
But there is room for improvement. We have made no significant progress towards mitigation of two very serious global anthropogenic harms: warming and ocean acidification. (Readers who have genuine questions about either of these concerns, either due to denialist noise machine induced confusion or their own curiosity, who have sought out answers in the IPCC Fourth Assessment Report should feel free to e-mail me their courteous queries. Your name, your city of residence, your query, and my response will be posted on a different 'blog.)
There's no sensible change Arizona, alone, could make to its policy to mitigate this harm. As was the case for ozone layer damage, Federal and international cooperation is necessary. There are small win-win improvements Arizonans can make, however, that can both lower home and business carbon footprints and save consumers money.
Arizona is rarely cloudy, and relatively close to the equator; solar irradiance is high. Solar water heating and solar electric generation can be cost-effective in many far cloudier places, but they make even more sense here. A properly installed system can pay for itself and more over its lifetime. Making the payoff even quicker are tax credits and incentives. An Arizona tax credit will pay for 25% of a residential solar hot water, heating, or photovoltaic system, up to $1000 per residence; the Federal tax credit, on which the cap was lifted, will pay for 30%.
Several of the state's electric companies also provide incentives. Tucson Electric Power provides up to $1,750 up front for residential solar hot water or space heating installations and $3 per watt up front for photovoltaics. The Salt River Project offers incentives for both, and a nifty web-based calculator of incentive levels and time to simple payback. Metro Phoenix's APS offers incentives at similar levels for solar hot water, solar space heating, and photovoltaics.
Other electric utilities elsewhere in the state might also provide incentives; check their websites. TEP and APS offer further incentives for geothermal and all are giving commercial incentives, as well. APS is now offering incentives for nonresidential installation of solar absorption cooling
Further governmental incentives are available for efficiency upgrades. See the Database of State Incentives for Renewables and Efficiency for more information.