> I know it may not seem strictly relevant to this
> forum to touch on current climate change, but here
> goes anyway. It seems certain that our man-made
> activities are contributing to climatic
> instability, but I do not buy into the exclusive
> obsession with greenhouse gases as being critical,
> especially as historically the CO2 rise FOLLOWED
> the rise in temperature. On the other hand there
> seems to be much evidence that the Jet Streams,
> four high speed tunnels of air flowing from West
> to East and located at the tropopause, driven by
> solar heat and the rotation and axis of the earth,
> themselves drive the weather below. Until 60 years
> ago, though doubtless variable, they were at least
> relatively undisturbed natural phenomena. Then we
> started to insert aircraft into them and this has
> continued increasingly as bigger, more numerous
> and faster commercial aircraft systematically hunt
> them while flying from West to East, and
> studiously avoid them while traveling from East to
> West. Newton would surely have agreed that since
> the jet streams are being used to change the
> flight of aircraft, there must be an equal and
> opposite effect of these jet aircraft on the
> flight of the jet streams. Is it commercially too
> inconvenient to ask for the answer to a simple
> scientific question; what effect are aircraft
> having on the jet streams, and if it is
> significant how might it be mitigated?
Probably not, David. It was thought that the no-fly days post 9/11 would show if aircraft had an effect on climate, but it seems now that that was not the case.
A study in 20021 suggested that these contrails could have a significant effect on daily temperature patterns (see 'Air-traffic moratorium opened window on contrails and climate'). But a new analysis now claims that altered US temperature patterns during the three flight-free days can be explained by natural variations in cloud cover, rather than the absence of planes.
If plane contrails in themselves don't have any measurable effect on climate, I don't think an increased number of contrail-producing aircraft would affect something as powerful as the jet stream, either.