"were plausibly said to have done more than anything else to turn the 'Reforming Tsar' Alexander 11 towards abolishing serfdom."
But the writing has to be precise and observant. Earlier in the preface, when discussing Alexander Herzen, Stoppard writes,
"What he detested above all was the conceit that theoretical future bliss justified actual present sacrifice."
Twentieth-century history was on Herzen's side. It's easy to imagine, today, that many playwrights' resistance to climate change as a political subject comes from this idea that it deals with a "theoretical future" and that it is being used to justify "actual present sacrifice". Playwrights like to write about real situations, flesh and blood characters, the here and now. And they like jokes.
In some ways, then, the most interesting characters to put on stage right now are climate scientists: not a climate sceptic disguised as a climate scientist (as happens in The Heretic), but the climate scientists who are simultaneously appalled and fascinated by what they are discovering.
At last year's TippingPoint conference in Oxford, climate scientists spoke candidly and wittily about how their work had altered their lives and their world views. If caught accurately, that kind of portrait might have real political influence.