The crucial effect of jet stream position on
the climate forcing effect of persistent
spreading aircraft contrails and contrail cirrus based on daytime temperatures in Bangor, North Wales
during 2006,2007 and 2013, by Dr Chris Barnes, Manager,
Bangor Scientific and Educational Consultants, July 2013.
Dr Barnes Homepage http://www.drchrisbarnes.co.uk
effect of jet stream position on the climate forcing effect of persistent
spreading aircraft contrails and ensuing contrail cirrus based on simple
observation of maximum daytime temperatures in Bangor, Wales during summer
months of 2006, 2007 and 2013 is evaluated.
It is found that flying at night always causes positive forcing
irrespective of the jet stream, although the positive forcing with a normal
summer jet stream position to the north of the British Isles us minimal. Flying
in the daytime with the jet stream in this position may cause very slight cooling
but the statistical relevance is not concrete.
In the case of jet stream which has been displaced equator ward thus
hitting the British Isles broadside from a Westerly direction, the climate
effect of persistent contrails and ensuing cirrus appears to be far more
serious. Possible explanations for these differences are proposed. Based on the results, the possible use of
jet aircraft as a means of local weather control is discussed. Perhaps as expected, the presence of low to
medium level cloud cover with or without coincident precipitation has a far
more dramatic negative forcing effect. Ship tracks are already known to
modify/create such cloud and use of ships as a mode of climate mitigation is
also discussed. At least over Britain,
ships and some air flights may already be off-setting all potential CO2
warming. In North Wales, however, climate and other anthropogenic changes such
as use of renewable energy technology are bringing major changes to hydrology
and this will be discussed elsewhere.
Finally, arguments against stratospheric engineering are advanced based
on disruption of the global electric circuit and catastrophic atmosphere/lithosphere interactions.
There is concern that
growing International air traffic emissions and contrails may be a major player
in global climate change (1). Indeed some including the present author
have suggested that contrails in various guises could be the major player in
climate change (2, 3) even
outstripping the positive forcing effect of CO2.
conditions however, and when laid down at certain times of day, persistent
contrails might also cause a cooling effect (2,3).
The present author has
also previously established two distinct weather cycles associated with contrails
and has suggested that their behaviour might be due to the type of natural or
anthropogenic aerosol nucleation particles entrained. There has been much conflict and uncertainty
in the scientific literature regarding effects of persistent contrails and
their attendant cirrus formations. For
an adjunct to the aerosol entrainment hypothesis it is instructive to look at
the effect of jet streams. De Grand et
al (2000) (4) reach the conclusion that climate forcing of
contrail outbreaks in the troposphere is always positive and weak based on the
fact that contrail outbreaks are more likely in association with jet streams,
cyclone waves and frontal systems.
More recently, Irvine
et al (2013) (5) ,studying New York
to London flights, have realised that not only the probability of contrails
persisting is influenced by climatic conditions but also is the climatic impact
of every single flight. They have also
noted that the climate impact of winter flights is greater because
stratospheric contrails occur. They have
also noted that the climate impact of westbound flights appears greater than
that of Eastbound flights. The
present author asserts that this is because many westbound flights are at
night. Irvine et al also remark
that the CO2 impact of Eastbound flights is weakest when there is a strong jet
stream tilted 'north eastwards' towards the UK.
There has been much
talk recently about the North Atlantic Jet Stream being displaced and often too
far Southwards, particularly in the
summer months. In the UK such displacement brings cool, more winter-like
temperatures and excessive conveyor belt driven rainfall. Jet stream positions are thought to depend on
a range of complex variables such as the NAO, El Nińo, solar cycles, volcanic eruptions etc. (6-12).
Some have even speculated they may be just the subject of random walk (13, 14). Others have suggested that CO2 driven climate
change is moving Atlantic jet streams in a pole ward manner (15, 16). Except in the month of September this does
not seem to have been borne out in the UK in recent years. If jet streams respond to stratospheric injection as a result
of volcanic eruptions than maybe also they are starting to respond to
anthropogenic aerosol. Thus in terms of
the climate forcing of aircraft and their contrails this opens up the
possibility for yet another unconsidered feedback mechanism. Some have said jet streams may also link to
modulations of geo-physical phenomena via the ionosphere (17), so perhaps we should not even rules out possibly influence of
World Power Grids and ionosphere heaters such as HAARP and SURA. Even the influence of turbulence from wind
farms should not be ruled out (18).
In July 2006 and for
some reason again in July (2013) the North Atlantic Jet stream has been in a
far more stable and natural summertime position tilting North Eastwards over
Iceland and remaining generally well to
the North of the British Isles.
Based on the above, the
present author viewed this as an ideal time to make a study of the effect of jet stream position on the climate
forcing effect of persistent spreading aircraft contrails and contrail cirrus
based on daytime temperatures in his home city of Bangor, Wales. Given that persistent and spreading contrail
outbreaks are often 100km wide there is some potential relevance for more of
Wales or even parts of the British Isles as a whole.
of the Study
The study has been
designed to make a comparison of the climate forcing effects of persistent
contrails and ensuing cirrus by comparing sets of daytime temperatures in
consecutive Summer months with and without a displaced jet stream and in the
same summer month with a normal and an
equator ward displaced jet stream.
In July 2007 the 300mb
jet stream was displaced towards the equator resulting in almost unprecedented
summer rainfall and flooding in the UK.
In much of the period between July 2007 and July 2013 the jet stream has
been too far south resulting in a lot of summer flooding and resulting in three
very cold winters. In July 2006 and in July 2013 the jet stream was in a more
normal position to the North of the UK.
For much of June 2013 ( 6th -22nd ) the jet
stream was also displaced to the
South. Indeed since the 1970's the jet
stream has often been displaced. Dr
Peter Stott, a leading climate scientist at the UK Met Office, states that
since the 1970s the amount of moisture in the atmosphere over the oceans has
risen by 4%, a potentially important factor.
Other possibly significant changes in the 1970's were; vastly increased
jet aviation, the first ionosphere heaters also transmitted. Following this, there have certainly been recent and
abrupt changes in the monthly distribution of regional weather types in the
British Isles. Such changes are thought by some to have began abruptly in 1981,
see Mayes (19, 20). Other
potentially significant anthropogenic changes potentially influencing the jet stream
were: the first wide bodied high bypass turbofan aircraft were introduced in
the 1980’s. (21) The
Sura Ionospheric heating
facility also commenced operations about this time (22).
The study will make a
comparison of the data from the three Julys and from June 2013. In more detail
the method involves calculating the
average temperature for four separate conditions with the exception of
July 2007 where shortage of data led to only three of the conditions being
met. The four conditions are peak daily
temperature data has been acquired from within those periods and averaged for:
days with no persistent contrails or contrail linked cirrus.
days with persistent contrails and linked cirrus.
24h after significant night time ( 7pm+)
persistent contrail outbreaks *
with overcast and /or rain.
Assumptions made in the
The main assumption
made is that flight numbers average out. The Bangor location is almost under a
major E/W flight path and reference to the website flightradar24 suggests this
to be a valid assumption. The other assumption made is that there is sufficient
homogeneity of atmosphere and temperature not to worry too much about the
precise location of each patch of persisting contrail or ensuing cirrus. For certain solar zenith angles this may not
be a valid assumption. Weather and
climate are naturally variable and random for this reason large standard
deviations in the temperature data are unavoidable and are, indeed, to be
Results and Discussion
The results in which ‘JS’ stands for jet stream and ‘Cons’ stands for the presence of persistent, usually spreading, contrails are tabulated below :
The results for July 2006 and 2013 (listed as 'summer 2006 and 2013' respectively in the table) with a normal summertime jet stream are remarkably similar. Based simply on average daytime maximum temperatures it would appear that persistent contrails have statistically very little effect if the jet stream is well north of the UK
If anything persistent
contrails which break out in the morning cause a very slight cooling effect
whereas the days after evening contrail outbreaks are marginally warmer,
presumably due to heat trapping and reduction of daily temperature range.
On the other hand when
the jet stream is displaced to the south so it strikes the UK directly the results (listed as summer 2007
(July 2007) and summer 2013 (part of June 2013) in the table) show a very different outcome, with
significant warming or positive forcing in both cases with an average of .38C
warming by day and a very significant 2.45C of warming on days following
evening persistent contrail outbreaks.
The data in the table
also shows another perhaps obvious, yet nevertheless, striking feature. That is
the temperature reducing effect of medium and low level cloud or overcast
whether or not associated with frontal precipitation. This is more pronounced
and statistically more relevant when the jet stream is displaced to the south
relative to its normal summertime position.
There has been talk of engineering the climate by stratospheric
injection. From these results, it would
appear that quite simply low level cloud creation would have a far more
dramatic and stabilisation effect. Ship tracks modify marine stratus and
indeed produce just this effect. They
may be indeed be offsetting virtually all CO2 warming. The crucial paper is
that of Eyring et al 2010 (23).
There has been much
talk of how to mitigate the climatic effects of air travel. The above results should significantly inform
this process. It has already been
suggested that moving flight times from night to day could significantly reduce
global warming (24). This present study
strongly supports that notion.
However, when the jet stream is displaced, use of contrail avoidance
algorithms is also advised. Also there
may be efforts directed at changing aircraft fuel or modifying exhaust
emissions to maximise ice crystal size and morphology which brings about
cooling rather than heating. The present author feels this ought to be possible
without resorting to potentially dangerous climate mitigation schemes such as
direct stratospheric injection and ocean seeding.
To re-iterate, the
findings, perhaps somewhat surprisingly suggest that at least over North Wales
contrail outbreaks which occur when there is a normal summer jet stream pattern
produce rather insignificant changes. Further work would be necessary to
determine the overall statistical significant of the weak daytime cooling
There are several
possible mechanisms which might explain the difference in the climate forcing
behaviour of persistent contrails and ensuing cirrus under these two very
distinct jet stream conditions. Firstly there will be significantly different
wind shear under the two conditions perhaps leading to different ice crystal
configurations which are known to favour positive or negative forcing see the
crucially important paper of Zhang et al (1999) (25),
secondly there will be different mixing of gases in the UTLS and, finally, there
will be different aerosol nucleation particle entrainments. For example, aircraft travelling on the West
East Atlantic route often fly in a favourable jet stream to conserve fuel. A displaced jet stream shortens the route and
it is expected that under these conditions over North West Wales there will be always
be significantly enhanced CO2, sulphate, ammonia and soot present in an almost continuously replenished transport
stream. This alone may be sufficient
to explain why there is so much extra positive forcing with the displaced jet
Contrails as a means
for local weather control.
These findings prove
beyond doubt that contrails have an inadvertent effect on weather and climate
and hence it is further proposed by the present
author that contrails could be employed as a means of
local weather control either as an alternative to or as an adjunct to
traditional seeding methods.
Interestingly, this point of view was first put forward by Murcray as early as 1970 (26).
A displaced jet stream
can cause significant cold weather and snow precipitation disruption in winter
and spring. It is anticipated that
contrail engineering could be used to
cause significance local warming as required
to mitigate snow fall and/or perhaps to change ice crystal shape/ size and/or
hydrological distribution because contrails are known to scavenge moisture from
other clouds and could be used to reduce precipitation n certain areas and
enhance it in others.
Climate control / Geo-engineering
for the future
Whether we like it or
not aviation has been inadvertently geo-engineering our climate at least since
the dawn of the jet era. The present
author is sincerely of the opinion that appropriate use of aircraft and ships, particularly the latter,
ought to be able to mitigate CO2 induced climate change well into the future.
Clearly, we should still strive to become carbon neutral because of the ocean acidification
and air quality degradation caused by the mitigating aerosols. These routes are however probably far more
preferable than injecting other hitherto untested materials into the
stratosphere and/or oceans. For
example, stratospheric injection as proposed by some, for example, Crutzen (2006) (27) as supported by Mac Cracken (2006) (28)
have catastrophic effects on the electrical properties of the atmospheric
medium, see Beig 2008 (29). Since the atmosphere
and lithosphere are coupled via the earth’s global electric circuit (ref) the
present author has very serious reservations against stratospheric injection in
particular. Of cause some inadvertent
injection occurs at the UTLS due to normal flying and some natural injection
due to volcanic action but surely we should not upset this sensitive balance
2. Barnes 2012 http://www.drchrisbarnes.co.uk/AIRWARM.htm
3. Olivier Boucher http://www.nature.com/nclimate/journal/v1/n1/abs/nclimate1078.html
4. J.Q. de Grand et al http://journals.ametsoc.org/doi/full/10.1175/1520-0450%282000%29039%3C1434:ASBCDO%3E2.0.CO;2
5. E.A. Irvine et al http://centaur.reading.ac.uk/25594/
6. Woolings (2010) http://onlinelibrary.wiley.com/doi/10.1002/qj.625/full
7. Price et al (1998) http://www.tau.ac.il/lifesci/zoology/members/lewi_files/documents/Price_GRL_1998.pdf
8. Tinsley (1988) http://onlinelibrary.wiley.com/doi/10.1029/GL015i005p00409/abstract
9. Stuiver et al ( 1995) http://www.sciencedirect.com/science/article/pii/S0033589485710794
10. Tinsley (1989) http://onlinelibrary.wiley.com/doi/10.1029/JD094iD12p14783/abstract
11. Zanchetin et al (2011)
12. Stenchikov et al (2006) http://onlinelibrary.wiley.com/doi/10.1029/2005JD006286/full
13. Woolings et al (2013) http://www.atmos.albany.edu/daes/atmclasses/atm305/2013/3Sep/Woollings_et_al_RMetS_2013.pdf
14. Frame et al ( 2013) http://www.met.reading.ac.uk/~sws97mha/Publications/grl50454.pdf
15. Kidston and Vallis
16. Riviere (2011) http://journals.ametsoc.org/doi/abs/10.1175/2011JAS3641.1
17. Waldock and Jones (1987) http://www.sciencedirect.com/science/article/pii/0021916987900444
23. Veronica Eyring
et al (2010) http://www.sciencedirect.com/science/article/pii/S1352231009003379
26. Zhang et al (1999) http://www.drchrisbarnes.co.uk/WXCONTROL.htm
( link to Murcray 1970)
29. Gulfrain Beig