I went to have the car's oil changed today armed with several back issues. Seems like I spend less time reading the biochemistry articles and more time reading ones related to the environment. So here is the issue. Millions of years ago, plants fixed carbon with photosynthesis, just like they do now, but the plants were buried in swamps and under heat and pressure, turned that carbon into oil, where it remained underground and safely buried away from the atmosphere. A hundred years ago, we started pumping it back out of the ground and burning it, turning back into the CO2 the plants had used. Not only is all that CO2 causing problems by trapping the sun's energy on the surface of the earth, but we have passed the peak of oil production, and what's left is not nearly as easy to find, drill and extract.
There are two workarounds I want to comment about. One is that methods have been developed to extract CO2 from the air and pump it into those empty spaces from which the oil has been taken. This puts pressure on the remaining oil and helps to remove the rest of it. That's just one strategy for carbon capture and sequestration. There are some dozen power plant demonstration projects underway and it will be interesting to see how that goes.
The other workaround is biofuels to replace the petroleum as it grows unattainable. Since I had a couple of biofuel customers recently, I have been reading up. Congress has mandated a 5x increase in ethanol production, which will require 44% of the corn grown in 2007, by 2015. So as the population grows and the climate warms, the US water consumption required for biofuels production will increase by 2/3 - that's water that isn't there, particularly in the western US. In India, e.g., the water table is rapidly dropping due to population pressures and increased crop irrigation. This is seriously not adding up to a sustainable technology.
I'm looking into my crystal ball and sure see a lot more questions than answers.