I have been reading The Revenge of Gaia, and am finding Lovelock's objective view toward climate change very interesting.
One of the most interesting suggestions in the book is a comment that while it's generally accepted amongst scientists that global warming will cause a change in current weather patterns, this potential for change gets overlooked when considering the future of tidal or wind powered energy projects.
Essentially Lovelock points out that what might be an area of strong winds or currents now - might become a dead calm location in the future, leaving us with no power generators.
I suppose to some extent the argument in favour of these renewable energy projects in existing windy or strong current locations is that by utilising the power available now we can avoid the more dramatic weather changes if we don't significantly reduce carbon emissions now.
Personally, I'm becoming increasingly convinced by the arguments that the only realistic alternative energy source is going to come from nuclear power. C02 levels are now guaranteed to go high enough to cause fairly substantial climate change - if not actually really quite severe climate changes, so staking our future energy requirements on a risky source is sounding less appealing.
Lovelock also points out the great unknown factor with renewable energy sources: we really don't know if wind farms of tidal barrages on a huge scale will have a negative impact on the environment that we haven't anticipated.
The argument against nuclear tends to be aimed at abuses of the power - not the power itself. In an ideal world, nuclear power is clean and not likely to be running out on us any time soon. The problem has come from the use of nuclear resources for weapons and radioactive waste not being disposed of properly. Problems yes, but I think problems that are actually more easily solvable than those raised with a renewable energy network. Certainly in the case of disposal - we know what the process should be for containment of nuclear waste, it is only a matter of ensuring these processes are enforced.