oldbiggincfi wrote:This morning, living in SE England , I woke to clear blue skies.
Very bright sunlight and a lot of sunshine warmth.
Not a contrail to be seen .
Are we going to experience increased surface temperatures as a result ?
What about solar panels - will they produce more ?
There is also a noticable difference in backround noise, few aircraft , and much less road traffic .
Thoughts please .
The science has been ambiguous on this for a while, but creeping up on making sense. The leading researchers in the world right now are two professors, one in Reading - Professor Keith Shine, and one at DLR in Germany, Professor Ulrich Schumann.
If you look at the IPCC (International Panel on Climate Change) reports you'll see that one of the biggest error bars is over aviation's contribution to radiative forcing (the basic mechanism by which the troposphere is net warming), and that is down in large part to contrail-cirrus.
The mechanism there is that contrails form through ice crystal formation around sooty particles emitted from aircraft exhaust during flight through regions of air supersaturated with respect to ice (that is the air is above 100% relative humidity, and below 0°C). Some contrails don't last, some persist, and some persist and grow - becoming contrail cirrus.
Contrail cirrus is believed to have two opposite impacts upon radiative forcing. In the day it is net cooling because it tends to reflect solar radiation : a mixture of short and long wave radiation back into space. At night however it tends to reflect emitted long wave (heat) radiation emitted by the earth's surface back into the earth - which is net warming. Now one obvious impact is that this gives cooler days and warmer nights locally, but the question here is about net warming or cooling.
That's the much tougher question, and I'm only on the fringes of this science, but my understanding is that the scientific consensus is heading towards a net warming effect. This means that aviation's contribution to anthropogenic climate change is probably closer to 4% of the recent total, rather than the 2% we've mostly been told (bad), but does mean we're starting to understand the problem a lot better (good).
So right now, the grounding of most, but not all, flights has probably removed about 3% of mankind's contribution to climate change.
I am Spartacus, and so is my co-pilot.