Fadell, one of the chief architects of Apple’s audio strategy (there were obviously others, and top Apple execs sometimes bristle at Fadell being credited with paternity), had been working as an adviser to Apple (AAPL) CEO Steve Jobs since being replaced in November 2008 by former IBM (IBM) exec Mark Papermaster. Now his time in that diminished role has ended and Fadell is moving on.

Fadell’s plans? “My primary focus will be helping the environment by working with consumer green-tech companies,” he told the New York Times, which first reported his departure. “I’m determined to tell my kids and grandkids amazing stories beyond my iPod and iPhone ones.”

Now that venture capitalists are so taken with green tech, perhaps they can push some VC dollars toward the development of a greener data center. Because according to consultancy McKinsey, data centers are fast becoming the Superfund sites of the tech industry. McKinsey found that data centers are responsible for 0.3% of the world’s carbon-dioxide emissions. That’s about half of what the airline industry generates–and by 2020 it will surpass it.

“The more you look, the more you find that the entirety of the IT stack, from the CPU up, is very inefficient,” said William Forrest, the associate principal for IT at McKinsey. “Data centers are becoming a major business issue. We think it’s going to become a regulatory concern that will drive scrutiny not just in (corporate) boardrooms but with regulators as well.”

So what’s to be done? McKinsey proposes that corporations at least double the efficiency of their data centers by 2012 and adopt its Corporate Average Data Efficiency metric, a sort of fuel efficiency standard for IT. Said Forrest, “It’s miles per gallon for data centers.“

Doesn’t make much of a presidential campaign slogan, either. But then it doesn’t need to. Because former Vice President Al Gore doesn’t expect to be a candidate for the presidency in 2008. But he is joining venture capitalist John Doerr as a partner in Kleiner Perkins Caufield & Byers, a storied venture capital firm that has backed some of the biggest names in technology.

Gore, who shared a Nobel Peace Prize this year for bringing attention to the issue of global warming, will quarterback Kleiner Perkins’s green-technology investments. “There is a flood of money coming into this area,” Gore told the Los Angeles Times. “A lot of it is undisciplined. When you open the hood and look inside, you see people shrugging their shoulders and saying, ‘We don’t know what we’re going to do.’ “

And that’s where Gore and Kleiner Perkins come in, using green–the Federal Reserve kind–to make green–the sustainable energy kind. Said Gore: “What we are going to have to put in place is a combination of the Manhattan Project, the Apollo project and the Marshall Plan, and scale it globally. It’d be promising too much to say we can do it on our own, but we intend to do our part.”

Clearly we’ve got a bit of a trend going on here. Said Bob Epstein, Environmental Entrepreneurs co-founder and study co-author, “It’s a bull market for clean technology.” Looks like the industry that some have pegged as “the next big thing” for a couple of years now may soon live up to that descriptive.

Greenpeace learned that Wednesday, when Apple chief Steve Jobs published an open letter addressing its indictment of Apple’s green practices. “Apple has been criticized by some environmental organizations for not being a leader in removing toxic chemicals from its new products, and for not aggressively or properly recycling its old products,” Jobs wrote. “Upon investigating Apple’s current practices and progress toward these goals, I was surprised to learn that in many cases Apple is ahead of, or will soon be ahead of, most of its competitors in these areas. Whatever other improvements we need to make, it is certainly clear that we have failed to communicate the things that we are doing well.”

Indeed. Especially to Greenpeace, which didn’t even
bother to actually measure toxins in Apple’s products. According to the Statistical Assessment Service, Greenpeace used Apple’s labeling to determine which chemicals are present in its products and then used the precautionary principle for those chemicals’ toxicity to calculate its green score. “In other words,” explains STATS, “if a study has shown that a chemical causes some damage in rodents, the precautionary principle dictates that one must assume the chemical is a risk to humans, no matter what the quantity, or the likelihood of actual exposure, or the mode of action, or the weight of countervailing evidence. If we applied the precautionary principle to vegetables as Greenpeace does to computers, we’d have to ban tomatoes and lettuce, as the naturally occurring caffeic acid is a carcinogen in rodents at high quantities.”

Nice, eh? It get’s better. According to the EPA’s Electronic Product Environmental Assessment Tool, Apple’s products are among the most environmentally friendly in the PC world. Which is not to say that the EPEAT is the best gauge of green standards, just that there exist data points that don’t support Greenpeace’s accusations against Apple. Anyway … green tech is obviously an important issue, and it’s wonderful to see Apple make a public commitment to environmental action like this–regardless of its inspiration.