CIOs in some leading-edge industries, such as Internet services feel the need to self-regulate before any carbon footprint-related legislation passes.

"In the UK, I will have to be reporting my carbon footprint based on regulations in the UK and EU," Digital Realty's Smith says. "Those same processes and reporting structures will impact my US operations."

Some state and local environmental regulations already affect CIOs. In California, Title 24 dictates energy-efficiency standards for buildings including data centers. King County, Washington, requires outdoor-air cooling for data centers.

"Title 24 impacts our California designs in a meaningful way," Smith says. "You'll find little [regulations] like this regionally. This type of pressure is growing."

As far as federal legislation is concerned, most observers expect it to be in the form of a cap-and-trade program or a tax that acts as a financial incentive to companies to reduce their carbon footprint.

"The big question is, how much will carbon be?" Gartner's Mingay asks. "If it's $120 a ton, then everybody will care a lot. ...The balance of probability is that companies will be paying for carbon in some shape or size. The $60 billion question is in what format."

"Legislative pressure is inevitable but probably not immediate," Skinner says. "A lot of companies are doing the baselining and benchmarking to see how they stack up, not only for carbon legislation but also for increased competitiveness."

Industry observers expect there will be an increase in legislative pressure on CIOs to go green. For example, in June the Lieberman-Warner Climate Act, which would have enacted a carbon tax, was voted down by the Senate. Many more similar bills are expected.

"There's all sorts of rumbling in the industry about a carbon tax. There's rumbling about the cap-and-trade initiatives and are we going to see that happen as an industry. Even if we don't think it's going to happen, it behooves us as an industry to start to measure carbon and get a good benchmark to use," says John Tuccillo, vice president of industry alliances for APC.

5. IT vendors

Green IT is one of those movements where vendors have been ahead of most CIOs and IT buyers. That means IT buyers are seeing a lot of hype from hardware and software manufacturers about why they need to go green.

Vendors are "painting everything green," Mingay says. "Some of it is credible. In some cases it's just plain green washing."

"There is an arms race among the server vendors to get the most efficient server that will operate in the widest range of temperature and humidity ranges, the one that provides the biggest bang for the buck," Smith says.

Green IT initiatives such as Climate Savers and The Green Grid are being driven by manufacturers including Intel, Google, Dell, IBM, HP, Microsoft and others.