There's an error in Pablo's calculations. A ream of 20 pound paper weighs 5 pounds, because a ream is weighed in 17x22 sheets. Thus, the 100 page document would weigh 1/2 pound, and require .145 pounds of greenhouse gas emissions.

The overall point is still valid, though. Printing would require 45% more energy than reading online. And that doesn't include the emission required to get the paper from the factory to the printer.

Thanks.

Well

but why did you not calculate the damage to the environment created by the manufacturing

of the computers and printers versus the manufacturing of the paper? Its not just a matter

of what your laptop does in the next five minutes, is it?? The manufacturing of the laptop

and all the laptops versus the making of typewriters or other printers etc .

Calculate all of that.

No matter how many times I look at something on a computer screen, it still takes printing it out to find the most basic errors. For example, typing "it" versus "is". If the program doesn't pick it up as a grammatical error, looking at the print-out I usually what I need to literally see it. I realize that my age may be part of the problem (I was born before pc's became the common media).

So for now, I use recycled paper when I need to print out a document and do edits on that before the final printout.

For 100+ page documents, however, I do the editing that I can on the computer, then print and hope I got all of the problems. Fortunately, I've not written anything that long that gets into a formal document (fingers crossed).

.........I'm about ready to emit some personal greenhouse gas of my own. Not to mention, (but I will), the length of time it took to create, write and post this article (who knows how much gas?) Multiply that by the number of people wasting energy just reading this thing; all six of them, (more gas). And you've got a recipe for global flatulence, Elsie the cow would be envious of.

Our in-house legal department is going 'paper' LESS. We still have hard files, but most documents received by computer fax, or electronically, or created in discovery through an electronic program, are stored electronically. Since so much is done via e-mail (the bulk now) I'd say most documents are NOT getting printed. We also try to produce documents in lawsuits electronically too, number them electronically, redact them electronically, so that everything is handed over, not in a stack of paper, but on a CD/DVD. Computer memory is also cheaper, so gigs and 'terrabytes' are not so expensive.

Problem is old-fashioned attorneys (most) who insist everything has to be printed too. Yes, you know who you are. I think the whole thing boils down to confidence, and the confidence levels are slowing increasing.

Systems are backed up each night, in duplicate locations, so the chance of actually 'losing' something is less than the chance that a sheet of paper will slide behind the desk, never to be seen again.

On the one hand: your calculations are based on your 30-watt laptop. Calculations using a 350-watt (or 500-watt) desktop "gamer" system would give you far higher numbers.

On the other hand: all these calculations assume that, absent the online reading, your computer would be OFF. The truth is that lots of computer owners and users (a majority?) leave their computers on all day, sometimes all day and night, whether they are using them or not. You certainly won't save energy if you print out a document and then leave the computer on while you read it.

More about paper weight.

The relation between "50 pound paper" and weight is more subtle.

But, for example, I just printed a 1000 page book, with heavy covers,

and it weighs 6.3 pounds. That's 500 sheets of "60 pound paper".

I don't think you would actually use paper much lighter than that

in your home printer.

So, you should have figured about .63 pounds for a two-sided 100 page

document.

Inkjet ink is roughly the unit price of plutonium dipped in the tears of the unborn, give or take.

Maybe some people do this, but in my office where we're still printing quite a bit of stuff... the computer isn't getting shut down while I'm reading the stuff I printed off. It stays on from the moment I arrive until the moment I go home. Even if you're planning on turning off the machine, you still need to be counting the amount of time you were on the computer while printing and then shutting the computer down, which for something the length of an email may be no longer than it actually would have taken to read in the first place.

Pablo's calculation of the weight of 100 sheets of ordinary printer paper did not sound correct to me. I could not imagine that they could weigh what he suggested. So I did some research — both online and using my kitchen scale. I learned that the typical 20 pound per ream weight for the 8-1/2 x 11 inch stock used in the US is for the original 17 x 22 inch sheets from which that stock is cut. Thus, a ream of 8-1/2x11 paper will weigh 5 pounds, not 20. And 100 sheets will weigh 1 pound, not 4. Printing double-sided will bring the paper weight down to 0.5 pounds. Being an engineer, I could not resist counting out 25 sheets of paper which weighed in on my digital kitchen scale at 3.2 ounces. I'll leave it to the interested student to confirm that this measurement (perfectly) confirms this discussion.

Using Pablo's conversion figure of 0.29 pounds of CO2 per pound of paper, the stock for our theoretical print job corresponds to 0.15 pounds of greenhouse gas, not 0.58.

Nonetheless, the argument still holds that reading the article on the computer is the more environmentally sound choice.

Interesting.. my parents will sit down at the computer, turn it on, do their thing, then turn it off. Amazing concept. I know a lot of Prius-driving recycle-loving types like myself that have probably never turned off a computer unless there's some real problem. Strange.