One of the resources that darkroom based photographers use a lot of is water. If you think fighting over oil and energy is bad, wait until we have poisoned our ground water to the extent that we can't drink it anymore. I'm not saying that photography is to blame for that, but it will be a more scarce resource in years to come.
It's also a fact that I use a lot of energy to heat the water that I use in the process. Safelight, enlarger light, dehumidifier for the darkroom in the summer, fan for ventilation, sometimes a heater to keep the temperature above freezing...
Another thing not mentioned here is all the waste. Each roll of film we shoot has a byproduct, a cassette full of plastic and metal, or backing paper and a plastic reel. We also cut off a bunch of film that doesn't get exposed, and the packaging the film rolls come in - where does it go?
What about all the photo paper that goes in the trash can? In my darkroom there's far more paper in the trash can than in my pile of finished prints.
As far as digital photography is concerned, it isn't just the manufacture of cameras that we should worry about. Memory cards, camera batteries need recharging AND replacing, you need a computer to view the pictures and to 'process' them, and backup hard drives to store them. Don't forget the energy spent by servers in cloud based storage (conservatively, 4% of our nation's energy goes to data centers), and the energy spent by those who look at the pictures, and transmit them from one storage point to another to do so. If you want prints you need a printer, with consumables such as ink and paper. All of those items (except the paper) are made from materials that constitute a danger to the environment, (although I'm sure it isn't friendly to make inkjet paper either).
What's worse is all of the nano technology involved with making digital equipment. It's one thing to use it to manufacture, along with all the nasty chemicals mentioned by others, but when those items are destroyed, the nano particles are released into the atmosphere, because there are no filters that are able to capture them. We breathe those particles, and our body's protective system cannot filter them, so they go straight into our lungs and into our blood stream. You cannot protect yourself, and the worst part is, nobody knows how it's going to affect the environment; there is no conclusive evidence. But it's called 'progress' and we must continue to feed those who can pay for the next greatest gadget, right? Keep that revenue stream alive and kicking, never mind what happens to the planet.
Bottom line: If you use the internet for anything, you are as guilty as anybody else. Most people in the modern world are severe polluters without even knowing it, because of the distance thing that PE is mentioning. It isn't easy to NOT have a big negative impact on the environment today.