Scientists fear that the world has reached the tipping point. We are at the brink of setting off cataclysmic changes here on Earth. Should these changes occur there'd be some doubts as to the survival of mankind. I believe mankind will survive, it won't be as easy as the last few hundred years or so, but we'll manage.
Current technologies are available for environmental protection. However, these are mostly deemed as too expensive (in terms of cost and in terms of effort). The perceived factor that will drive people to pick say coal over hydro (when generating electricity) would have been the price. Coal, oil and other fossil fuels were cheap. These are also energy rich. When the cost of oil sky-rocketed the venture capitalists (the people who fund other people's "bright" ideas) invested heavily in green tech. This appears to me highly reactionary and not visionary. It was a knee-jerk reaction to the high cost of oil and not a consistent investment plan into viable alternatives to fossil fuels.
Sure ethanol has been touted as the bio-fuel of that will end most developed nation's addiction to oil. However, engineering alternative energy from food supplies (sugar, corn etc.) will serve to create cheaper fuel and at the same time jack up the cost of food. Using jatropha and other non-food bearing plants could be a solution but it wouldn't be a scalable solution. It would most likely be a one-off project. I think the Jatropha solution started in India or Pakistan and was seen as a means of creating cheap diesel fuel in the Philippines. It was scrapped as to make a plantation of jatropha would take away so much of the scarce arable land that we have left. Algae is still a few years off, we tried experimenting with it and lacking in scientific know how the project perished. We were able to prove the concept of algae as a source (as has everyone else, we merely based our work on their's) but the concept of a bio-fuel as a privately run small-scale enterprise was something we could not prove.
Bio-fuels are something I think would serve to wean away demand from oil but would not solve the environmental issue. Bio-fuels are there to attack the problem from an economic standpoint and not from an environmental view.
I have no idea how to fix this. I'll think about it!