"However virtuous, virtual science is no substitute for the real thing"

Here.

Excerpts:

When I was a member of Greenpeace in the 1980s I received a request for money supported by the claim that about 30,000 species each year were becoming extinct. Until then I'd been an unsceptical environmentalist, but this sounded like an awful lot, so I called Greenpeace to ask how they knew. I made several queries but they didn't seem very interested. Finally they told me they didn't know where the figure came from, and I resigned from the organisation.
...
Kellow describes one paper published in the journal Nature in January 2004 that "warned of the loss of thousands of species with a relatively small warming over the next century...Kellow notes that a similar warming over the previous century had not left anything like the trail of species devastation being proposed in the paper, yet this observational data was considered irrelevant compared with the virtual world of the models.