Finally a topic area where I feel am somewhat qualified to comment. But bugger me were to begin?
First the term environmentalism. Like all name tags for groups of people it captures a diverse range of views and objectives. From your advocates of sustainable development (continued economic growth is good but just needs to be done in a more thoughtful way) through to the Deep Ecologists (nature first and the quicker Homo sapiens becomes extinct the better). In the middle a whole bunch of people - informed and ill informed, those that are just concerned through to those that are passionate (and somethimes violent). Basically people like anyonw else but with an underpinning belief that humans are part of nature and that for reasons of morality, self preservation, or profit we can and should do better.
Second the economics of environmentalism. Lead is a good example of what ecological economist call an negative externality. Externalities are an unpriced benefit or cost imposed on a third party (in this case a cost).
Because they are unpriced the market (really people making decisions in a market) cannot take account of them and there is either an over supply (if it is a cost) or an undersupply (a benefit) of that product or service.
Economic theory clearly states that when you have a signficant externality you have a market failure and their is an economic justification for intervention to correct that failure.
Most attempts to do include a price of a negative externality into a market involve environmental taxes, or cap and trade regimes. When these are well designed they can result in environmental gains (the SO[sub]2[/sub] market in the US has often been cited as a good model). The emerging carbon trading market is another example of a cap and trade regime (too early to tell what effect it will have).
However, these changes to the market are designed to impose extra costs on pollutors with the specific aim of changing their behaviour (i.e reducing emissions or moving into another activity). If the regime doesn't result in changed behaviour it is just imposing a cost on society with no net welfare improvement. In this case the regime design needs to revisited.
Often those that are benefiting from passing on their environmental costs to others for free have considerable political clout and use this to retain their 'rental' at the expense of the rest of society. In these cases the market design is often eroded or set up to fail from the outset.
Third point on Michael Crichton. Dr Crichton is an example of an all too common problem - the unqualified pundit acting like an expert in a field outside their expertise. His tactic is a common one - first redfine the problem in a way that has nothing to do with what the science is actually saying (which is always much more complex and subtle than what is reported). This is the 'strawman'. Then set about in witty and erudite fashion to destroy their own strawman. I have seen this done with regard to:
Climate science
Evolutionary theory
Cosmology
Ecological sciences (pretty much all of Lomborg)
and of course the Peak Oil theory.
People like Crichton and Lomborg can do this because the body of science/evidence that explains these theories is:
complex and uncertain
always wrong (a better theory will come along) and will never proven to the satisfaction of those that want the "Truth" (What is this Truth shit anyway)
changing with new intreperations and evidence.
Most people don't have the time, inclination, mental capacity (sorry its true it takes talent, effort and discpline to be a good scientist and even then they often don't grasp it all) to come to grips with what science can tell us and is telling us. People also want certainty and science does not provide this either.
All these factors gives the pundits a huge amount of wiggle room.
Anyway for those of you that want to take the time to grapple with some science (which is most probably wrong but is the best understanding that we have at the moment) gird your loins and go to
http://www.realclimate.org/index.php?p=74
Wher they discuss Dr Crichton and his comments on human generated climate change.
Good luck
Rincewind
PS I do agree with Dr Crichton on one point. We cannot destroy the planet and there will be life on Earth long after humans are gone. Extinction is a normal part of life (at least on this planet). I would rather, however, have it occur later rather than earlier.