There are two kinds of people: optimists and pessimists. Sadly, I'm one of the latter. So I wasn't surprised when the vast majority of scientists concluded that human contributions to the buildup of greenhouse gases are a key component of global warming.

I sometimes wonder, What's the use? After all, China and India are just getting started as major producers of greenhouse gases, and the U.S. government seems unwilling to lead this nation in efforts to conserve energy. The future looks very bleak.

Unless you talk to the right optimists.

I recently had the privilege of chatting with John Engates, chief technology officer at Rackspace Managed Hosting in San Antonio. His company has eight global data centers running more than 30,000 servers for 10,000 customers, primarily small and midsize companies. Engates is not only an optimist, but he's also someone with the authority to make changes in how his company consumes energy within its core business operations - the data center.

Naturally, Rackspace is already doing a lot of the things that experts say can cut energy consumption in the data center (see "Seven Steps to a Green Data Center," by Robert Mitchell). Like many organizations, the company is aggressively pursuing server virtualization. The goal is not only to reduce its server count, but also "to get better utilization of system memory," Engates says. As Robert Mitchell pointed out (see "Memory: The New Power Hog," April 30, 2007), RAM power requirements in new servers are double those of CPUs.

As data center managers seek to cut power costs, servers get most of the focus. But Rackspace looks at all the gear it uses. Energy concerns now affect how the company buys and deploys network switches and routers. Engates' goal is to reduce unused network ports, which translates into fewer machines and less power used.

Engates emphasizes that "thinking green" goes beyond looking at what you plug into an electrical socket. You need to look at your entire operation. Because Rackspace buys so many identical servers from the same vendor, it has arranged for the supplier to stop including redundant cables and manuals in each box, so there's less packaging to throw away.

At a more strategic level, Rackspace has committed to using electricity generated from renewable resources. Its new data center in the U.K. will be run completely by biomass- generated power. "Its electricity that will be grown instead of mined," Engates says.

For each server Rackspace buys and places in U.S. data centers where renewable energy sources aren't available, the company buys offset energy credits from Native Energy in Charlotte, Vt. Native Energy uses that money to develop renewable-energy projects. And Rackspace has joined The Green Grid, a consortium dedicated to cutting data center power consumption.

But being green goes beyond the IT department, Engates says. To that end, Rackspace holds "Green Days," where everyone in the organization can learn about ways to cut their own personal carbon footprint. At these events, workers are introduced to everything from Toyota's hybrid Prius to the local dry cleaners' green cleaning techniques.

There's more Rackspace can do, Engates says. And he admits that one company alone won't save the planet from overheating. But Rackspace will keep plugging away.

"And progress is being made," Engates insists optimistically.

Indeed, after chatting with him, this is one pessimist who is a bit more hopeful.

Mark Hall is a Computerworld editor at large. Contact him at mark_hall@computerworld.com.