It is certainly hard to pick a particular attitude because I think that we all feel a little of each at different times. My Modern Environmentalist outlook is based on my Tech-Fix and Gloom-And-Doom attitudes. I think if we use science for the right reasons; such as finding natural energy sources (other than oil), or learning more about our earths past in astronomy or ecology studies. Although our atmosphere is heavily polluted we have come a long way since the 1970's as far as smoke filters, outlawing garbage and chemical smoke-stacks, and increasing the recycling of paper, plastic, and glass. Unfortunately I am a little pessimistic about our earth's future because of the mass outbreak of recent warfare.
I don't think our earth can handle the new wave of nuclear bombs (whether it be for testing of bombing). I don't know if it will happen in my lifetime, but as fast as science can start to clean and help our ecosystem, science can also destroy it. This seems to be earth's inevitable fate as our home. I hate to be so depressing but Rosy-Optimism just seems too easy. It may have worked if everyone started that way. But it may be too late to keep ignoring our environmental problems.
The frontier Attitude is my least favorite attitude, even though like many of us I use too much paper, forget to recycle, leave the water running while I'm brushing my teeth. All of the simple things that some of us take for granted fall into the frontier attitude towards the environment. Some entrepreneurs also use the frontier attitude as they are more concerned about their profits than pollution the harm they are doing.