Cassandras

One point to note about "the Greens as Cassandras:"

Cassandra's curse was that she was right, only people didn't want to hear.

Many problems that were earlier decried do seem to have been solved…
but was it really because the market naturally solved them, or rather
because environmentalists' warnings were heeded and pressure resulted in legislation?!

Moreover, there is one excellent point about having Cassandras:

No one will be able to say that we never knew that "that" could possibly happen.

All negative arguments about dangers and the need for sacrifice (and so on)
do not create the necessary motivation for actually changing, however…