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Nicole Foss has been back for another go on Facebook. It seems that no matter how much evidence you put up they on't be convince- they simply refuse to look at the evidence.
Late
October Sees Strong Polar Amplification, Mangled Jet Stream Impacting
Much of Antarctica
30
October, 2014
Globally
speaking, it’s a rather hot day.
According
to GFS model runs and observational data, the past 24 hour period has
shown temperatures in the range of +0.72 C above the already hotter
than normal 1979 to 2000 average. A hot day in a hot month that is
likely to be among the hottest on record, if not an all-time
record-breaker itself.
A
couple of days ago, hourly CO2 levels rocketed from 396 ppm to 399.5
ppm. A rather odd and somewhat ominous jump back toward the 400 ppm
level at a time of year when atmospheric CO2 should be just starting
a slow rebound from lowest ebb. A bottom that this year hit about 395
ppm during mid September. A measure already more than 2.2 ppm above
last year’s low. To say the least, an hourly upward swing of 3.5
ppm isn’t exactly normal, especially when one considers the fact
that the world hasn’t seen near 400 ppm CO2 levels for about three
million years (this year peaked near 403 ppm during late spring).
And
all that extra CO2, when combined with other greenhouse gasses, is
having an increasingly obvious impact on climate. We see it in the
record global average temperatures. We see it in the rising oceans
which have come more and more to threaten the cities, lands and isles
upon which so many of us reside. We see it in increasing instances of
extreme weather around the globe — in the extraordinary and often
persistent droughts, floods, storms and wildfires. And we see it in
the form of a rather strong temperature amplification at both poles.
(Global temperature anomaly maps provided by GFS and the University of Maine shows no regions of the world cooler than average with the highest abnormal warm temperature departures concentrated, as usual, at the poles.)
Greenhouse
Gasses as Primary Driver of Polar Amplification
Today,
the Arctic is 1.60 C above the already hotter than normal 1979 to
2000 average. Meanwhile, the Antarctic boasts the highest departures
for any global region at +2.09 C. Taking a closer look at the
Antarctic Continent, we find an angry red splotch featuring
temperature anomalies in the range of +12 to +20 C above average. A
region associated with a tropics-to-pole transfer of airs we’ll
discuss more in depth later.
What
causes such a powerful and visible polar amplification? In short, it
can best be described as the general impact of added greenhouse
gasses on the global climate system.
Because
most of the sun’s radiation falls on the equatorial regions,
temperatures there are governed to a greater degree by direct solar
insolation. But move toward the poles where sunlight hits the earth
at a much lower angle, if at all, then the impact of the greenhouse
effect holds greater sway. There, the ability of a gas like CO2 to
trap and re-radiate long wave solar heat radiation can have a rather
extraordinary impact.
On
an Earth with no atmosphere, the temperature differential between
poles and equator, between night and day, would be even more extreme
than the variance we see today. But as the atmosphere thickens and
the greenhouse gas overburden intensifies, the temperature difference
grows less. For Earth’s present climate the temperature difference
between the Equator and the Arctic averages about 42 degrees C. For
the Antarctic, the average is about 71 degrees C.
On
a world like Venus, where a kind of super greenhouse is in force and
much of the atmosphere is composed of CO2, there is practically no
difference in temperature between the equator and the poles. The
reason for this is that greenhouse gasses trap the sun’s long wave
radiation and recirculate it around a planetary system. And on Venus,
a ray of long wave sunlight that comes in has very little chance to
get out. So its heat recirculates many times within Venus’s
atmosphere before it finally escapes.
On
a place like Earth, where greenhouse gas levels are increasing, we
would expect the temperature difference between the equator and the
poles to drop as the poles warm faster due to the added impact of the
increased greenhouse gasses. And since about the mid 20th Century,
this is exactly what we’ve seen.
(Top frame shows North Pole to Equator temperature difference since 1948. Bottom frame shows South Pole to Equator temperature difference from 1948 to 2011. Note the approximate 3 C temperature swing indicating a faster warming at the poles in both graphs. Data is from the NCAR-NCEP reanalysis model.)
Lowering
differences in Equator to polar temperature on a warming world also
denotes a much faster warming of the polar zones. Hence the term
polar amplification.
Now,
for the Arctic, polar amplification has also become synonymous with
loss of sea ice, loss of snow cover, increased land darkening due to
changes in vegetation, and local release of greenhouse gasses via
feedbacks from the Arctic environment. Each of these changes has the
potential to add increased warming on top of the warming already
being driven by global greenhouse gas increase even as such changes
likely also drive changes to local and Northern Hemisphere weather.
But as important as these additional changes may be, the larger
driver remains an increase in global greenhouse gases driven by human
emissions.
How
Polar Amplification Drives Changes to the Jet Stream
In
the end, such a polar amplification is a strong driver for changes to
the world’s weather. Primarily, by reducing the difference in
temperature between the poles and the Equator, we tend to see
weaknesses forming in the circumpolar wind field known as the Jet
Stream. At times, the Jet will slow and meander, allowing for the
formation of ridges that extend far into polar zones and for troughs
that dip deep into the middle and lower latitudes. Rather than a
west-to-east flow of wind and weather, such a shift generates more of
an Equator-to-pole flow:
(Triple tendrils — meridional flows converge on Antarctica. Note the massive highs sitting in the ridge systems driving the poleward wind flows. Image source: Earth Nullschool.)
And
today we see two large north to south flows issuing from the 20
degree south latitude region, traversing thousands of miles of ocean
in a poleward flood and terminating at the great ice sheets of
Antarctica in the region of 70 to 75 south latitude.
Note
that the flow originating off the west coast of South America
terminates at the vulnerable West Antarctic Ice Sheet — a region
that has been warming at an extraordinary pace of 0.25 to 0.5 C each
decade. The second flow, originating from the South Atlantic and
terminating over East Antarctica is heavily involved in the +12-20
degree C temperature anomalies ongoing there today.
Looking
at these massive flows of air and the related spikes in temperature
anomalies, it is easy to become confused over the issue of cause and
effect. But it is simple to recall if you understand that first,
added greenhouse gasses warmed the pole which in turn weakened the
Jet Stream, which in turn allowed an amplification of the north-south
meridional flow transporting yet more heat into this southern polar
region.
For
the southern polar region, today, we see some extraordinary high
temperature departures for mid-to-late spring. At this time, polar
amplification should be fading as more sunlight streams in. And yet
we have a still strong positive temperature anomaly.
And
as for the northern polar zone with its numerous additional polar
amplification vectors, we shall see to what degree, if any, a
potentially emerging El Nino tamps down the extraordinary meridional
flows and polar vortex disruptions seen during just this past year’s
freakish winter of 2013-2014.
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