Aviation
more adequately accounts for global temperature change since 1940 then do
earthbound CO2 concentrations, furthermore aviation and ships account for recently stalled
warming and new trend towards cooling by Dr Chris Barnes
Bangor Scientific and Educational Consultants
Dr Barnes' Homepage Link http://drchrisbarnes.co.uk
Abstract
Global temperature rise
between 1940 and 2000 is shown to correlate far better with world air flight
numbers than incremental earthbound carbon dioxide increase. Aircraft contrails
have a much stronger climate forcing effect than carbon dioxide. However when
contrails evolve into cirrus like cloud with appropriate ice crystal size,
shape and distribution, particularly if daytime flights dominate there can be a
net cooling effect. Shipping too induces an enormous cooling effect. Taking the
air corridor which passes to the North of Bangor in Wales as an example, the
author has noticed a predominance of this type of cloud evolution only over the
last decade or so. When data up to 2011 is included global warming as a
function of air flight numbers appears to have stalled. When a quadratic fit is
applied a new trend of cooling is predicted.
It is thus proposed that this can be adequately explained by the switch
from linear to spreading contrails and subsequent cirrus evolution. It is further proposed that by adjusting ice
crystal size and distribution a method of low cost geo-engineering should be
feasible. Contrails and cirrus cloud can alter planetary hydrology budget and
can also encourage the formation of low pressure systems or potentially alter
the course of weather systems so more
research and a cautious approach will be essential. Aerosols injected by
aircraft absorb UVB light and contrails reflectively scatter the same. UVB is essential
for vitamin D synthesis and healthy living, additional caution will be needed
here
Quotation
|
"Discovery
consists in seeing what everyone else has seen and thinking what no one else
has thought." |
|
-- Albert Szent-Gyorgoi
Von Nagyrapolt |
|
|
Introduction
Over the past thirty
years or so there has been considerable debate over global warming. In its
heyday it was stated that 97% of climate scientists accepted global warming and
doubtless most accepted that global warming was caused by anthropogenic
greenhouse gas emissions particularly carbon dioxide. However, greenhouse gases including Carbon
Dioxide and others would be expected to mix by various diffusive processes
throughout the planetary atmosphere yet most of global warming is observed in
the Northern Hemisphere. 74.6% of the
entire World’s air traffic is also in the Northern Hemisphere http://www.choike.org/documentos/tourism_help_poor.pdf.
On the other hand cloud generated by aircraft, although having a residency half
life significantly and orders of magnitude
less than that of C02, would be expected to remain more localised and is
regularly replenished while ever aircraft remain in the skies.
Thus to the present
author it is blatantly obvious that here is a most obvious potential
association between air traffic and global temperature change which has not
been adequately investigated to date.
Very recently indeed the UK met office have released data from the
Hadley Centre that appears to show that global warming is over or at least that
there has been a sixteen year pause [1]. The work presented here below will very
broadly support this but for hitherto unconsidered reasons.
The present author is
not a climate scientist by training but does have scientific training and is
educated to a high level in both scientific and engineering disciplines.
Further the present author has a number of international publications and
patents and patent specifications. Further the present author has during the
last decade or so been turning his attention to unexplained physical and
environmental phenomena and has a number of internet publications on the same.
The present author has also a keen interest in the weather and has local
temperature and rainfall records going back to 1981.
Living in North Wales
under a busy air corridor the present author has witnessed changes in the skies
above and changes in the local climate on a previously unprecedented scale. At
first sight these do not appear to be changes for the better. The skies appear far cloudier, particularly
with contrails and aviation cirrus and the mean temperatures have been falling
significantly. Indeed once could say
that whole new families of hitherto rare or unseen cloud types have been
spawned in recent times. The average member of the public who does not have an
interest in natural science and who does not look up at the sky would, perhaps,
not even notice these changes. Such displays are interesting in other senses as
one can visualise AGW’S in real time.
One can also see the most phenomenal solar optical displays ranging from
cloud edge iridescence in blue and orange or pink and green to sun dogs and
full solar or lunar halos and circum-zenithal arcs. Prior to the last decade such displays
were extremely rare and might only be seen in Alaska and Northern
Scandinavia. These displays are
associated with ice crystals usually at cirrus cloud heights.
The present author has
noticed that almost all these
phenomena appear to arise from aircraft contrails which often don’t
dissipate but spread out into huge sheets with often the most spectacular patterns. Ship tracks too cause similar
patterns. One can see evidence of wake
vortex induced swirl in these patterns and sometimes evidence of Kelvin
Helmholtz instability. In other words
text book type fluid dynamics type processes can be visualised in real time by
a ground to sky observer! From a cloud
perspective you can see fall streaks, hole-punch effects and mammantous and scuds at times you would not normally expect.
The author asks two questions if all these spectacular, perhaps local, effects have developed as a result of
aircraft in the last decade or so firstly, are such effects more widespread and
secondly surely they will be having a profound
effect on both weather and climate?
Indeed so concerned about these changes was the author that he placed an
article in his local newspaper several years ago and also contacted a scientist
at the UK Met Office. He also recently
took discussions with a leading climate scientist in the USA regarding the
cooling he had noticed. He also took discussions with a contrail scientist and
an optical physicist regarding the optical effect he had noticed. Persistent
contrails are not entirely new. They were first noticed in WW2 but there sudden
proliferation in all our skies since the turn of the millennium demands the
application of some serious science.
From the point of view
of a lay person commonsense dictates that cloud ought to cool the planet by
screening out the sun. The true picture is of course far more complicated than
this and depends on both Long and Short Wave radiation effects; cloud optical
depth, ice crystal or water droplet size and distribution etc.
It is rewarding to see
then that aviation science has at least now caught up with the personal
observations of the author and indeed from a Google Scholar literature search
it would appear there is presently intense research going on into the climate
forcing effects of aircraft contrails.
The consensus of this research appears to be that linear and spreading
contrails have a positive climate forcing effect i.e. they warm the
planet,[2] , however the paper goes
on to say that possible changes could be made to aircraft to change this into a
cooling effect.
However, when contrails
or aerosol form aircraft spread out to form cirrus like cloud, presumably the
likes of which the present author has been observing the picture is far less
straight forward. Natural cirrus has a
warming effect [3]
Some scientists have
concluded that contrail cirrus has also a warming effect [4] http://www.met.reading.ac.uk/~sgs02rpa/PAPERS/Haywood09JGR.pdf
and [5] Atlas et al 2006 http://journals.ametsoc.org/doi/abs/10.1175/JAM2325.1.
However, for both
persisting contrails and contrail cirrus when ice crystal size and its
distribution is taken into account, a different picture emerges, see Zhang et
al 1999 [6] http://directory.umm.ac.id/Data%20Elmu/jurnal/A/Atmospheric%20Research/Vol52.Issue1-2.Aug1999/835.pdf. See also Geerts
and Linacre 2002 [7] which also
refers to the cooling effect of ship tracks
http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/contrail.html.
Whereas, some remain
convinced that further studies will be necessary, Ramanthan
1987 [8]
http://www.agu.org/pubs/crossref/1987/JD092iD04p04075.shtml.
Finally, Sassen concludes contrail cirrus may cause cooling
depending on such factors as day and night flights. Cooling is favoured by
daytime flying. [9] http://cat.inist.fr/?aModele=afficheN&cpsidt=2828565.
In this respect it should be noted that in Britain night flying is very limited
which ought to support the Sassen model[10]
http://www.richmond.gov.uk/home/environment/pollution/noise_pollution/aircraft_noise/night_flights/current_limits_for_night_flights_at_heathrow-5.htm
Hypothesis
Atmospheric Carbon
dioxide levels are still increasing due to anthropogenic activity yet global
warming has apparently stalled. Either
carbon dioxide is not responsible for global warning or another (feedback?)
process or other processes are countering the increase due to carbon dioxide by
themselves causing a cooling effect. If
carbon dioxide is not responsible for global warming in modern times then what
is? Based on the author’s observations
it would seem logical to explore the once unseen possibility that a large
proportion of or even possibly all of global temperature change might be due to
aviation. The author does not regard his temperature data of sufficient quality
to employ in the testing of this hypothesis so only internationally published
data available in the public domain (Internet) will be employed. If air flights
alone rather than anthropogenic CO2 are responsible for global warming then
there should be a better correlation with the former. Furthermore in many parts
of the World, including here in North Wales, spreading persistent contrails and
contrail cirrus have only been noticed by observers on the ground for about
that decade. If these do in fact
contribute to global dimming or global cooling as has been hypothesised by some
above then this should be noticeable in say a plot of total number of air
passengers versus temperature. Indeed
if there are only two major processes at work, one warming due to the contrails
alone and one cooling due to the contrail cirrus or aerosol effects then this
plot should fit a simple quadratic equation.
Data
The data sets used in
this study are shown graphically below:
Figure
1 Aviation fuel use and emissions since 1940 courtesy of http://www.cate.mmu.ac.uk/research-themes/climate-change/impacts-of-aviation-on-the-climate/
Figure
2: Global Temperatures since 1860 courtesy of http://www.planetseed.com/relatedarticle/temperature-change-history
Figure 3 Linear regression plot 5 year average
temperature from figure 2 against aviation fuel use from figure 1.
( period 1940-2000)
Figure 4: Linear
regression plot 5 year average temperature from figure 2 against total
anthropogenic CO2 emissions from figure 1.
(Period 1940 -2000)
Figure 5: Linear
regression plot 5 year average temperature from figure 2 against total aviation
CO2 emissions from figure 1.
(Period 1940 -2000)
Figure
6: Total revenue passenger kilometres
since 1970 Courtesy of Money Week.com
Figure
7 Linear regression Global temp change
Versus RPK 1970 -2000
Figure
8: Total World Air Passengers
Figure
9: Global temperature change versus
total number of air passengers (cumulative World data obtained from central
source)
Figure
10: Global temperature change to 1970-
2011 versus passengers per annum quadratic fit
Discussion
of the results
The results show
unequivocally that in two of the modern times periods considered, namely 1940
-2000 and 1970-2000, aviation use correlates significantly better with global
temperature change than total anthropogenic (mainly earthbound emissions) carbon
dioxide does. In the period 1940 – 2000,
aviation use has been assessed using the only available data in terms of either
fuel usage or aviation carbon dioxide emissions both of which will have some
considerable bearing on contrail emissions.
For both cases the correlation with global temperature change is
significantly higher R=.973 and .96 compared with R=.93 for total anthropogenic
CO2. One would perhaps expect a better
correlation for fuel usage as it is other combustion products such as particulates
and water vapour from the fuel which give rise to contrails. This is an outstanding result especially
given that aviation technology has changed over the period. Long haul aviation technology changed less in
the period 1970 -2000 and this is borne out by an excellent correlation between
global temperature change and total passenger number in that period, with a
regression factor R= .993*.
Since 2000 many
different types of contrails and contrail cirrus clouds have been seen by the
present author in the skies over Bangor North Wales and in different parts of
the UK. Shipping especially container shipping is also increasing
significantly and contributes toward new
types of cloud formation due to salt spray. Likewise contrails and new cloud types these are often
seen by visitors to other countries or on television broadcasts or internet
sites from other countries.
If one takes the view that a majority proportion of these persisting contrails and
contrail cirrus clouds and ship tracks
can create a cooling effect in line with the consensus of scientific
publications then this should be directly observable in the climate data. It is certainly observable in the author’s
own data wherein his part of North Wales appears to be experiencing the coldest
summers since his records began. The
only available point in the climate data is a point for 2011 indicating a rise
of .52 Celsius with respect to the 1860 -2000 mean. When this data point is fed into the above
linear equation* together with the corresponding number of air passenger’s data
point for the same year a significant deviation from linearity is noticed hence
a slowing down in the warming rate is noticed. It is logical to suspect that
the slowing down process was introduced sometime in the interim. In terms of a
time period then perhaps anything as far as 13 years before the present and not
that inconsistent form the recent claim of the UK met office [1]. If the total data from 1970-2011 is refitted
to a quadratic equation a near perfect fit with a regression factor R=.998 is
obtained. It is instructive to use
this fit as a predictive algorithm. If
aviation growth continues as forecast there will be 3.6 Billion air passengers
annually in 2016. The algorithm predicts a continued cooling trend with a
temperature only .44 Celsius higher than the mean.
As an alternative or addition to the above it
is possible that negative feedbacks associated with climate may also be
relevant such as lapse rate and black body radiation. In lapse rate, the atmosphere's temperature
decreases with height in the troposphere. Since emission of infrared radiation
varies with temperature, longwave radiation escaping
to space from the relatively cold upper atmosphere is less than that emitted
toward the ground from the lower atmosphere. Thus, the strength of the
greenhouse effect depends on the atmosphere's rate of temperature decrease with
height. Both theory and climate models indicate that global warming will reduce
the rate of temperature decrease with height, producing a negative lapse rate
feedback that weakens the greenhouse effect. Measurements of the rate of
temperature change with height are very sensitive to small errors in
observations, making it difficult to establish whether the models agree with
observations. With black body radiation,
as the temperature of a black body increases, the emission of infrared
radiation back into space increases with the fourth power of its absolute
temperature according to Stefan–Boltzmann law. This increases the amount of
outgoing radiation as the Earth warms. The impact of this negative feedback
effect is included in global climate models summarized by the IPCC. What will not be very relevant or what will
only be of second order consequence will be Carbon Dioxide negative feedback
effects as this present work has shown that CO2 is not the main driver of
global temperature change.
It
cannot be stressed that for the observant sky watcher the hereinabove referred
changes in contrails have been very dramatic. Possibly because of this, a growing number of
individuals world-wide have subscribed to some sort of a Conspiracy theory
known loosely as ‘Chemtrails’ whereby they have
believed that a number of chemical
additives have been added to aircraft contrails or sprayed out by aircraft with
various goals such as climate and weather modification in mind. Such hypotheses
are perhaps not that wildly fanciful, given for instance that there are
obviously a huge number of published patents for both cloud seeding
methodologies and contrail modification, both enhancement and suppression http://www.geoengineeringwatch.org/an-exaustive-list-of-patents/
[11].
Even without the need to invoke anything sinister, clearly a chance
change in aircraft design in recent years, the author suspects this to be
switching to higher engine bypass ratios may be what has changed contrails and
our skies beyond previous recognition but yet also be what slowed global
warming appreciably since approximately the start of this millennium.
However, we ought not
to be complacent. Increasing CO2 levels
may not be causing global warming but
they are contributing to ocean acidity
http://www.pmel.noaa.gov/co2/story/Ocean+Acidification[12].
Furthermore we should not be complacent because although global
temperature increase has stopped or halted, global climate change in the form
of extreme weather events would appear at least in some parts of the world to
be on the increase [13] http://focusonfloods.org/wp-content/uploads/2011/02/Observed-Variability-and-Trends-in-Extreme-Climate-Events-A-Brief-Review-Easterling-1999.pdf.
Furthermore more contrails can affect planetary hydrology and the movement of
larger weather systems. Aircraft also
inject aerosols into the atmosphere which absorb and scatter UVB [14]ftp://copernic.udg.es/pub/jordibad/98JD02350.pdf. Given that 50% of Britain’s have been assessed
as being Vitamin D deficient in the last 2 years there is another serious note
of caution here. Contrails also reflect UV due to Rayleigh scattering.
Geo-engineering
It
would seem possibly that our saviour from run-away global warming is a chance
event of inadvertent geo-engineering. Following logically from this it would
seem that both aircraft and ships offer a cheap option for climate and weather control in the future.
One possible problem is
that some countries have already highly developed cloud seeding and microwave
and ion based weather control systems, and, albeit these would only be expected
to operate on a local basis weather is chaotic fractal system with often
wildly unpredictable knock –on
effects.
One can only hope that
weather wars will not or have not already ensued.
Further
work
One can only properly
test the aircraft global warming hypothesis fully by removing all aircraft from
the skies. One can of course employ contrail avoidance strategies by flying at
heights and places in the UT and below which are warmer or not at Relative
Humidity conceive to contrail formation.
However even an aircraft without a noticeable contrail is still
producing aerosol and water
vapour. With regard to contrail
avoidance there are also several patented methods for this used with certain
types of military aircraft. If it were
practical to incorporate these into the civilian passenger fleet, contrail
avoidance might be able to take place at heights and places in the atmosphere
where less fuel would also be used.
Conclusions
The present work
strongly supports the hypothesis that it is global air traffic and not anthropogenic carbon dioxide which
has accounted for most global temperature changes in the period 1940 -2011. A chance change in aircraft engine design has
possibly been our saving grace from runaway warming. The author concurs with Boucher that by
adjusting the microphysics and or chemistry of contrails we should be able to
take far more control over their global environmental effect in future. In making such changes however, we should be
very careful not to create scenarios which would starve our World’s population
of essential UVB. [15]http://www.telegraph.co.uk/health/healthnews/9742176/Plethora-of-diseases-caused-by-low-vitamin-D.html
or create global dimming to the detriment of vegetation on earth.
Of course finally no
discussion of these topics would be complete without reference to either those
who don’t accept any anthropogenic causes of global warming or those who think
its demise is best left to mother nature, for example [16]
http://books.google.co.uk/books?hl=en&lr=&id=f5p76GoayfgC&oi=fnd&pg=PR5&dq=global+warming+hype&ots=l_TmZ1k76v&sig=fw_4HCTRyTo1u46hPUG88v5QyQE#v=onepage&q=global%20warming%20hype&f=false.
Acknowledgements
The author wishes to
acknowledge his wife and son for interesting discussions on contrails. He further wishes to acknowledge his son for
providing interesting photographic evidence of weather research circular type
of contrails. Finally the author wishes to thank Mr Peter Van Doorn of the Torro Tornado
Research Organisation for years of valuable scientific contact and
discussion.
References
2.
Olivier Boucher http://www.nature.com/nclimate/journal/v1/n1/abs/nclimate1078.html
3.
http://www.atm.damtp.cam.ac.uk/people/sf371/publications/fueglistaler06b.pdf
4.
http://www.met.reading.ac.uk/~sgs02rpa/PAPERS/Haywood09JGR.pdf
5. Atlas
et al 2006
http://journals.ametsoc.org/doi/abs/10.1175/JAM2325.1.
7.
http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/contrail.html.
8.
http://www.agu.org/pubs/crossref/1987/JD092iD04p04075.shtml.
9.
http://cat.inist.fr/?aModele=afficheN&cpsidt=2828565
11. http://www.geoengineeringwatch.org/an-exaustive-list-of-patents/
12. http://www.pmel.noaa.gov/co2/story/Ocean+Acidification
14. ftp://copernic.udg.es/pub/jordibad/98JD02350.pdf.