Oz Blog News Commentary

Are feedbacks here already?

June 28, 2019 - 19:42 -- Admin

Almost a year ago, a scientific
paper appeared in the Proceedings of the US National Academy of Sciences
detailing the feedback cycles which it suggested were likely to kick in at
about a 2 degrees C increase over the pre-industrial level (we are now at 1 degree
C above this level). I wrote about it in September 2018 and noted these feedbacks
included: thawing of the permafrost; weakening of land and ocean carbon sinks;
increased bacterial respiration in the ocean; and Amazon and boreal forest
dieback. The authors of the paper suspected that these would add another half a
degree on top of that 2 degrees C by the year 2100, but that these could lead in
turn to a cascade of feedbacks after that time1.

Early this month I
reported on a concerning increase in the concentration of methane in the
atmosphere. It had been increasing about 1 part per billion per annum, but this
has now jumped to 10 parts per billion per annum. It is even worse at
mid-altitudes in the atmosphere with an increase of 35 parts per billion from
2017 to 2018. It was suspected that this increase was caused by a combination
of thawing of permafrost and the release of methane from hydrates on the sea
floor2. However, there was little evidence to actually sheet it home
to these specifically.

Now, a recent paper
dealing with time series observations (between 2003 and 2016) at several permafrost
sites in the Canadian High Arctic has been published in the journal Geophysical
Research Letters. These sites are of very cold permafrost which normally has a
mean annual ground temperature of -10 degrees C or lower. When these areas thaw,
they cause the ground surface to subside, and the data obtained indicate this
is happening much more rapidly than expected, and is producing small thaw
(thermokast) ponds. This is because the Arctic is rapidly warming, and between
1990 and 2016, it has increased up to 4 degrees C, considerably more of the global
average increase of 1 degree C3,4. The Intergovernmental Panel on
Climate Change (IPCC) tends to be conservative in its assessments, and its ‘moderate’
climate change modelling predicted that thawing of permafrost on this scale
would likely not happen until later this century, probably around 2090. The
fact that it is happening 70 years earlier than those moderate models suggest
is alarming. This is so because it allows microbes to start converting what trapped
organic material there was in the permafrost into carbon dioxide5.
This is feedback starting now, and it will probably be impossible to stop.

As if the threat from
methane2 and carbon dioxide5 wasn’t bad enough, now we
have another greenhouse gas to worry about. Back in 2010, the US Environmental
Protection Agency expected the amount of Nitrous Oxide (N2O) to be
released from thawing permafrost to be negligible. However, a recent paper
published in the journal Atmospheric Chemistry and Physics demonstrates that Nitrous
Oxide emissions from permafrost are about 12 time higher than previously
assumed7,8. Since Nitrous Oxide traps heat some 300 time more
efficiently than Carbon Dioxide, this could mean that the Arctic and thereby
the global climate are in more danger than we thought.

As I have said above and elsewhere6, the IPCC reports, by their very nature as consensus documents, tend to be conservative in their predictions. This may also be true of the paper on feedback cycles likely beginning when global mean temperature reaches 2 degrees C above preindustrial levels1. These feedbacks seem to have already started and that means that human civilisation is in grave danger.



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