Are Digital Photos Really Cleaner than Flm?

Hey Mr. Green,

During my recent Hawaii vacation, I watched tourists taking thousands of pictures and pondered the value of new digital technology in avoiding the millions of rolls of film and bad pictures that used to be processed. Do you have any idea about the savings in chemicals, film, and photo paper thanks to digital photography? Seems like a real green boon to me.

--John in Hinsdale, Illinois

Actually, the digital method isn't much easier on the environment than old-fashioned film. Sure, it takes chemicals to develop film, but think of all the toxic substances needed to make computers, printers, and ink cartridges--not to mention the hazardous waste involved in their disposal.

Since the two photography methods have such different impacts, it's a mind-boggling task just to set up a comparison because of the huge number of variables.

Digital does beat film in two realms--energy use and greenhouse-gas emissions--but isn't great in the categories of water use and waste generation. According to the most impressive study I've found, by Michael Muir at the Georgia Institute of Technology, the least energy consumption and greenhouse-gas emissions occur in digital photography when the user has an LCD monitor and ink-jet printer. This requires about half as much energy as retail film processing and releases about 40 percent fewer emissions. However, it requires much more water (digital manufacturing is a water-intensive industry) and can generate 10 times as much waste.

Also, with all digital technology, so much depends on how it's used. Even if you never print your digital images, you still wear out batteries, burn through memory cards, and spend hours gaping at them on-screen. That's when your digital efficiency can lose its edge. Fiddle around in Photoshop or upload any of those shots as screen savers, and your energy usage flies off the charts.

To put things in perspective, consider that guy in the tuberculosis sanitarium in Thomas Mann's novel The Magic Mountain. In his room, he keeps an X-ray image of his girlfriend's lungs. True, processing the film for that X-ray required resources, but if instead of gazing at the film, he'd persistently visited and venerated the same image on his PC, he could have very well exceeded the environmental burden of the X-ray film over the course of the relationship.

 

How Do I Offset My Carbon Footprint?

Hey Mr. Green,

I'd like to grow my own carbon credits by planting Douglas firs, which can live for more than 500 years, on my woodlot. How many do I need to plant to offset my carbon footprint?

--Larry in Vancouver, Washington

Planting trees is a splendid activity, but it's hard to plant your way out of global warming unless you have lots of land. And 500 years in the future is too remote for even Mr. Green to render a plausible prophecy. By then, your prospective Dougs might be thriving brilliantly, or driven to extinction, or exist only as DNA spirals in a spacecraft carrying your distant progeny on a galactic quest to find a planet to replace the one we wrecked.

So let's look a modest 50 years ahead instead. If you're an average American, you now emit 22 tons of carbon dioxide per year. In 50 years, you'll have pumped out 1,100 tons. To soak that up, you'd need to plant some 270 Douglas firs, assuming all of them make it to age 50. However, only 35 percent are likely to live that long, so you'd need to plant about 800 trees--requiring some 11 acres--to compensate for the firs that are bound to fall.

However, you can get by with planting fewer trees if you emit a lot less carbon dioxide than the average person. To find out where you stand, try the EPA's household emissions calculator at tinyurl.com/epacalc.