Ahem A Rivet's Shot wrote:
> they've always seemed to
> need to be unreasonably large, it's surprising to me if the combined
> contrails makes a large enough reflector to have such an effect.

Depends on how you view it. If contrails weren't a by-product but the
purpose for all those planes the cost would be ridiculous.

> if it were
> proven and the next move was to encourage widespread air travel in order to
> improve the climate.

I expect that just making existing trails denser and more visible for
the existing flights would not be hard problem to solve.

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