This is not from a “conspiracy theory” site but from the august publication, New Scentist
It turns out planes are even worse for the climate than we thought
By Michael Le Page
27 June, 2019
The
contrails left by aeroplanes last only hours. But they are now so
widespread that their warming effect is greater than that of all the
carbon dioxide emitted by aeroplanes that has accumulated in the
atmosphere since the first flight of the Wright brothers.
Worse
still, this
non-CO2 warming effect is
set to triple by 2050, according to a study by Ulrike Burkhardt and
Lisa Bock at the Institute of Atmospheric Physics in Germany.
Altogether,
flying is responsible for around 5 per cent of global warming, the
team says, so this figure will soar even higher – and no meaningful
actions are being taken to prevent this.
“Lots
of people talk about the need to stop air traffic increasing all the
time, but this is not taken that seriously,” says Burkhardt.
“The
non-CO2 warming is the elephant in the room,” says Bill Hemmings of
Transport & Environment, a Belgium-based campaign group.
All
aircraft that burn fuels leave behind a trail of exhaust fumes and
soot. At high altitudes, water vapour often condenses on the soot
particles and freezes
to form a cirrus cloud that
can persist for seconds to hours, depending on temperature and
humidity.
Burkhardt
and her colleagues used a computer model of the atmosphere to
estimate how much warming contrails caused in 2006 – the latest
year for which a detailed air traffic inventory is available – and
how much they will cause by 2050, when air traffic is expected to be
four times higher.
Read more: Earth could warm by 14°C as growing
emissions destroy crucial clouds
The
model accounts for not only of the change in air traffic volume, but
also the location and altitude of flights, along with the changing
climate.
The
team concludes that the warming effect of contrails will rise from 50
milliwatts per square metre of Earth’s surface in 2006 to 160
mW/m2 by
2050.
In
comparison, the warming due to CO2 from aviation will rise from 24 to
84 mW/m2by
this time.
Hard to cut
But
reducing contrail warming won’t be easy. “It’s much harder than
CO2,” says Burkhardt, and we aren’t doing anything effective
about that either.
“There’s
absolutely no doubt that aviation CO2 needs to be addressed properly,
and there is absolutely no doubt that it is not being addressed at
all effectively,” says Hemmings.
An
international scheme called Corsia is supposed to limit aviation
emissions.
Read more: EU set to resist air industry attempts to limit
climate change action
And
then there is the non-CO2 warming. “The attitude has been that
there are uncertainties, so let’s sit on our hands and do nothing,”
says Hemming.
There are
indeed large uncertainties whenever clouds are involved,
says Burkhardt, but these go both ways. The study could be
underestimating contrail warming by as much as 70 per cent.
The one
bit of good news is
that as contrails become more common, they reduce natural cirrus
cloud formation by using up all the water available. This cuts the
overall warming effect attributable to contrails by a fifth.
https://www.atmos-chem-phys.net/19/8163/2019/
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