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Iceland’s volcanic cloud keeps the sky clear of planes: will that cause more nocturnal cooling?

The sky’s bright blue right now, which is weird because I am
looking up through a 5,000-metre thick plume of volcanic ash from
Iceland. This has stopped all flights in the UK air space and much
of northern Europe.

(As somebody quipped on the radio, `Dear Iceland, we said send

So there are no vapour condensation trails from jets, which
prompts the thought: did anybody ever figure out what con trails do
to the climate?

One study estimated that the 3-day shutdown in US aviation
after 9/11 increased diurnal temperature range by 1C!

Another study in the Journal of Climate in 2004 concluded

It is concluded that the U.S. cirrus
trends are most likely due to air traffic


the cirrus trends over the United States
are estimated to cause a tropospheric warming of 0.2-0.3C [per]

That’s huge. Anybody know if these studies still hold up?


By Matt Ridley | Tagged:  rational-optimist