You spend years trying to get people to take an interest in aircraft emissions. Then at last the issue gets picked up — but in the most perverse way possible.
The pollutants spread by planes are a major issue. They make a significant contribution to global warming, yet they are excluded from international negotiations, such as the conference taking place in Paris at the moment. As a result, aviation's expansion is unchecked by concerns about climate change.
This exclusion is ridiculous, not least because aircraft emissions have a particular role in heating the planet, due to the height at which they are released, and the multiplying impacts of the water vapour and other gases the planes produce. Gases that sometimes form contrails in the sky.
So you might expect me to be delighted by the fact that thousands of people are taking an interest in contrails and their effects, and campaigning against the airlines producing them. Far from it.
For the most vocal people protesting against aviation emissions have no interest in their contribution to global warming. Quite the opposite. Many of those now denouncing the pollution of the skies see climate science as part of the problem: a conspiracy by corporations, military planners and other nefarious interests to control the atmosphere.
Until recently, I ignored this movement, even as it spread among people I knew. So pervasive have the rumours become that the government, which seldom responds to conspiracy theories, felt obliged this summer to produce a fact sheet debunking the principal claims.
But it was only when the editor of a major environmental magazine sent me what he called "a remarkable essay" in the hope of persuading me to take up the cause that I decided I could ignore it no longer. The "remarkable essay" was garbage: a long series of disconnected facts tacked together to create what appears to be a coherent narrative, but that bears as much relationship to reality as a speech by Donald Trump. On a bad day.
In my home town, the streets are now littered with graffiti advertising the website www.look-up.org.uk. So I looked it up. You might imagine, in reading what follows, that I'm picking an extreme example, but I'm sorry to say this is typical of the hundreds of sites promoting this nonsense. I keep meeting otherwise-intelligent people who seem prepared to believe it.
Here are its main contentions: