There's this perception that Greens are these ultra far left, unrepentant return to the Earth, long-haired hippy tree huggers and believe modern civilization should be torn down and humanity should return to its Gather roots (not so much Hunter because we should all be Vegan).
This is pure, unmitigated, bull. Are there some people like that, sure there are. Then again, there's also the Sovereign Citizens movement which is given as an example of nutbags on all ends of the spectrum.
A former boss of mine, a Glenn Beck and Ayn Rand love-child and ultra-conservative, took advantage of the cash-for-clunkers program (a Progrom he railed against vociferously, but was first in line to use, and I am being literal about that, he had the dealership hold the car he wanted for a week before the program started) to buy a hybrid SUV. And as he told me, he did it because of the economics, not because of the Green value and impact (he was real big on "economics"). He was surprised by my response (you know, other than to call him a hypocrite).
It's always been about the economics.
The vast majority of us Greens aren't PETA members, makers of home-made granola bars, anti-industrial, (popular culture's opinion of) Amish values, chain ourselves to whales, vegan zombies. We personally like a lot of modern conveniences, including indoor plumbing and central heat. We also eat meat. Mmmm, meat.
But we understand that what we do has consequences both for us, for our neighbors, for our nation, and for our world. And so that we try to minimize the impact we have. And that's what it's really about, making smart choices.
An example, I mow my lawn with a gas lawn mower. Not very environmental, at least to some people. However, I've used a push (non-powered) mower before when I was young and a client didn't have gas money. I'm too old to do that. My mower is quite ancient, also not exactly good for the environment. However, my mower is now nearly 20 years old (which means I'm not buying a new one every 5 years like my neighbors, that reduces my carbon footprint). I maintain it very well to make it as efficient as it can me. And over half my property is wooded (carbon sink, no need to mow, lowers the ambient temperature of the yard and my house, etc). It's a trade off.
This is why electric cars work. Sure, they also pollute (pollution to make, pollution at the power plant to charge, tire waste, and other incidental pollutants that all cars incur). Sounds like not too good of a solution. Except that the pollution to charge is less by a factor of 10, it starts looking better. That most cars would be charged overnight, when electrical use is at its lowest (that might seem counter factual because of lighting, but it's true because of lower air conditioning use, cooking, etc). So, while not perfect, electrical cars are better.
Even cars like the Volt which includes a small gas engine. That engine will produce less pollution to throw the same amount of weight down the road as an efficient 4-cylinder. The argument about how the best selling truck outsells all hybrids combined falls apart at this point because 1) hybrids are still a minority of vehicles produced, and 2) the truck platform would be perfect for a scheme like the Volt. Electrical motors have full torque at low speeds, trucks are sold on their torque. Trucks have the space and weight characteristics to hold the tech necessary. Why they aren't there yet is because of the entrenched beliefs of car execs/engineers, and their previous campaigns against electric vehicles.
So now that you understand at being Green is a series of conscious decisions and trade offs. Is it the best option we could think of? No, often not. However, we know we live in a modern world. The solution is to minimize the impact (because even living like a hermit off the grid incurs a carbon cost, it's never free). We have to do things like fly for our businesses, we have to drive, use electric, heat our homes, etc. But we can choose options that lower our impact (fly coach on direct flights, use fuel efficient cars/carpool, choose energy saving appliances and turn off things we don't need or put them on switches, and have high efficiency heat plants and a well insulated home).
There are times when the choices are all bad. And when that happens, you can mitigate your impact by doing offsets elsewhere. Now, you may not be able to fully offset your use individually, or you don't have the time, or the opportunity, whatever. But you do have money. And you can pay someone else to make those offsets for you. It would be nice if the offsets were local. But pollution is global and if your money helps another place not have the same problems that your causing to your local environment, that's better than nothing. I may not be able to buy green energy in Ohio anymore, but if my offset payments can buy solar powered items (or put together with other people's offset payment) that keep another power plant from being built in another country (while also bringing modern conveniences, like the "light mat" being sold in rural India), that is still helping the world.
And that's how offsets work and why they're available. I have to increase my carbon footprint to do something I need to do, I can pay someone an amount that offset that carbon use elsewhere in the environment. And all the small payments together can make big differences.