Dear Alan--When observationalists are clear the observations of ice
thinning and retreat are
right, and the modelers are insisting that the physics is the model
is properly constructed
and correct, then, if there are inconsistencies between the two, what
needs to be looked at
very carefully is the forcing, or more specifically, the changes in
the forcing over time.
Specifically, there have been changes over time in the sulfate and
black carbon forcing that
affect the solar radiation budget and also cloud albedo, and there
have been changes in the
tropospheric ozone concentration (as well of the greenhouse gases,
which need to be treated
specifically and not using CO2e). I'd suggest that all it would take
are some relatively
modest problems in some of these forcings as the region has gone
through the issue of Arctic
springtime haze and the its "clean up" as SO2 emissions in Europe and
North America grew and
then cleaned up much of the SO2 emissions, as the black carbon
loadings changed as growth of
diesel emissions of black carbon changed and were somewhat reduced,
and then as China has
grown. Calculations in Navarro et al, 2016 make clear that changes in
forcing can influence
the Arctic. I'd just suggest that a hypothesis that I think likely
needs some exploration is
that it is the time history of the forcings that could explain the
difference between the
observations and the models, and that it might be more productive to
look at this alternative
hypothesis as a way of explaining their differences.
I'd also note that I suggest this as only one alternative
hypothesis--there may well be
others. In any case, I'd suggest finding some possible explanation(s)
for the differences and
to get working on reconciling and understanding the reasons for the
differences--which is
what science generally aims at doing rather than simply blaming the
other side.
Best, Mike MacCracken
On 11/23/16 1:50 PM, Alan Gadian wrote:
Reto and Peter,
ECMWF is the best forecast model in the world. If you had attended
the change of
directorship last Spring, you would have heard them say that the ice
model predictions
( and they have the HIGHEST resolution forecasting model) are
terrible, do not predict
changes and have little connection with reality. My climate model
has taken 250 days
on 12,000 cray cores and I only achieve 20km resolution. ( I
estimate I used about 2
million dollars of electricity in the end, as some of the model is at
2-3km resolution.
It has possibly been one of the biggest projects on ARCHER.
ECMWF can run globally at 2-4km resolution. How is it also that
Martin Miller , who
masterminded much of the ECMWF model said of AR5 , that the clouds
were so badly
predicted that the radiative balance is not correct, and the climate
models could not
be trusted for clouds and radiation? He was one of the worlds best
experts,but
ignored.
Also then, How is it that then the climate models can do so much
better than the best
weather prediction models in the world? When the data evidence of
the HUGE changes in
ice volume and extent, are so apparent, so much so that by the time
AR5 went to press ,
six months after writing, the ar5 ice extent predictions were outside
the predicted
range for the worst scenario, how can the ar5 community still try to
sell the story?
Maybe Trump took his lead from the climate modellors?
I have had endless arguments with Piers Forster , another lead author
on ar5 about
this. scientists who know about modelling the weather have been
ignored. You do not
get papers published which day that models are wrong, only when you
say how great they
are.
In essence ,after AR3, it has become a gravy train for academic
careers based largely
on CXXP models. In a short time these models will be shown to be
catestrophically
wrong, and all that is done is to pillory those who try to point out
the true science.
Regards
Alan.
T --- Alan Gadian, NCAS, UK. Email: [email protected] &
[email protected]
Tel: +44 / 0 775 451 9009
T ---
On 23 Nov 2016, at 15:32, P. Wadhams <[email protected]> wrote:
Dear Dr Knutti, I would like to intervene in this seemingly
interminable
thread to draw attention to errors which you have made when you
mention my
work.
1. " But the natural variability is very large (e.g. Kay 2011,
Swart 2015, Screen 2013, 2016). There is no reason why short
term trends could simply be extrapolated, and the
predictions
by Peter Wadhams of sea ice disappearing by today have not
happened so far"
a) I completely agree that natural variability is very large
and stress
this in my book "A Farewell to Ice" which I suspect you have
not read. In
the book I stress that it is the TREND which is rapidly
downwards towards
zero, not that every successive year features a monotonic
decrease in
summer ice volume. And, despite the newspaper reports which
seems to
constitute your reading matter on my work, I do NOT forecast
that the ice
volume will go to zero in a specific year (like this year),
only that it
will go to zero in a very small window of years (of which this
year forms
one) as opposed to the decades which are still forecast by the
worst of the
current models. You might also care to glance at the current
NSIDC charts
for ice volume (Arctic and Antarctic) which show an
extraordinary turndown
since September suggesting that the co-operative collapse which
I have long
projected through my thickness measurements is now happening.
b) Why can't
short term trends be extrapolated? Firstly, they are not short
term - they
date back to the 1980s when observations began. And secondly,
please name
the magical effect which will cause the trend to become invalid
and the ice
volume to pick up again.
2. > Maybe the models are missing something, but it's just as
plausible
(and
in most scientist's view more likely) that the models are
largely consistent with observations within natural
variability.
Your idea of "most scientists" is an odd one. When the
observations show a
rapid declining trend leading to zero very soon, how can models
(which
predict decades of continued summer sea ice) be consistent with
these
observations? They are simply not consistent, and it is clear
that by "most
scientists" you mean "many modellers", some of whom have never
seen sea
ice.
3. I'm not
downplaying the strong changes in the Arctic, but the
science
suggests a fairly linear (and reversible) relationship
between
Arctic sea ice and temperature with large variability
superimposed. In my view they do not support a "death
spiral".
Well, it's obvious that there is a linear relationship between air
temperature history and sea ice thickness. The "degree days of
cold"
analysis dates back to the 1950s and was amplified by Maykut and
Untersteiner's analysis in 1971. But if air temperature is
increasing
rapidly, as it is, then thickness will decline just as rapidly,
leading to
a period in summer with zero thickness, in other words, a
"death spiral"
QED.
To paraphrase Captain Scott, I don't think I need say more,
Best wishes
Peter Wadhams
--
You received this message because you are subscribed to the Google
Groups
"geoengineering" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to
[email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/geoengineering.
For more options, visit https://groups.google.com/d/optout.
