About Saving the Earth ...
It ain't a pretty picture. Earth, as we know it, is dying, or apparently so. This is a transition period for the earth, and we'd like to see the transition take place smoothly. There are a lot of approaches - best approaches for a variety of people.

We can all do our bit.

One of the best books that I've come across is The Consumer's Guide to Effective Environmental Choices: Practical Advice from the Union of Concerned Scientists. They have comprehensively reviewed all of the activities that consumers, not industry itself, do that create "normal" and toxic pollution. They identify, the degree of water, soil, and air pollution. This gives the user a great tool to really identify how, "I", as an individual, can help.

Of course, the number one item is, cars, light trucks (including SUVs). The Guide says:

"The first mistake to avoid is buying a car that is bigger or more powerful than you really need. These days light trucks (including [SUVs, vans, and pickups]) are all the rage among affluent consumers. (The fraction of vehicles sold that are light trucks grew from 16.5% in 1980 to 40% in 1996.) The bad news for the environment is that the average new light truck gets only 20.5 miles per gallon, while the average new passenger car gets 28.5. Even more important, both cars and light trucks have gotten much heavier and more powerful in the last decade. If it weren't for this trend, fuel consumption by personal cars and trucks would be 15% lower than it is today."

"Allthough we have resisted assigning an overall ranking to the different categories of personal consumption, it is hard to avoid the conclusion that the personal use of cars and light trucks is the single most damaging consumer behavior. It is a major direct cause of greenhouse gases and many types of air pollution, and indirectly, it is also a major source of water pollution (through manufacturing of cars, oil and gasoline production, and runoff from highways) and ecologically harmful land use (for the road network). What can ordinary consumers do about it?"

"The key is to choose a car that meets your regular or typical needs, not your extraordinary needs. Television ads notwithstanding, most of those who own four-wheel-drive all-terrain vehicles rarely drive through blinding rainstorms on muddy hillsides."
...

"Once you have decided on the appropriate size, look for the most fuel-efficient and least-polluting cars (often the two go hand in hand) in that class. The range of performance is wide -- usually a 50% difference or more between the most and least fuel-efficient vehicles in a class. Even between vehicles of the exact same size and weight, the differences between the best and worst choices can be 20% or more. So a little research can make a big difference."