[climate change] effects [of Arctic warming] are identified … : 1)
weakened zonal winds, and 2) increased
[Rossby] wave amplitude.
These effects are
particularly evident in autumn and winter consistent
with sea-ice loss… Slower progression of upper-level waves would
cause associated weather patterns in mid-latitudes to be more
persistent, which may
lead to an increased probability of extreme weather
events … — Evidence
linking Arctic amplification to extreme weather in mid-latitudes,
Dr. Jennifer Francis and Dr. Stephen Vavrus, Geophysical
Research Letters (emphasis dded)
recent disruption in the quasi-biennial oscillation was not
predicted, not even one month ahead. —Dr.
unexpected disruption to the climate system switches the cycling of
the quasi-biennial oscillation forever.
believe that the quasi-biennial oscillation could
become more susceptible to similar disruptions as the climate
warms. — Physics.org (emphasis
said it before, and I’m going to say it again — loss
of predictable seasons, or seasonality, due to human-forced climate
change is very big deal.
And regardless of how all the scientific details specifically pan
out, there are now observed changes to Northern Hemisphere winter,
possibly due to human-forced warming, that are apparently starting to
undermine its traditional seasonal climate behaviors. As a result,
weather patterns appear to be shifting toward greater extremes and
lower levels of predictability.
— One of Our Most Predictable Atmospheric Clocks…
decades now, scientists have been observing a kind of atmospheric
clock tick-tocking high above the Equator. Up in the stratosphere, 10
to 13 kilometers above the Earth, winds tend to flow either east to
west or west to east. These air flows change
direction about every 28 to 29 months. This
feature, called the quasi-biennial oscillation or QBO, has never
significantly varied. It has always flowed in one direction for a
predictable period of time and then switched to flow in the other
flowing at this level of the atmosphere over the Equator have a
on the winter climate of northern Europe.
There, westerly high-level
Equatorial winds are known to bring warmer, wetter
winters. Easterlies in
the stratosphere over the Equator are known to bring cooler, drier
winters. The key to remember is that the QBO has always been both
amazingly predictable itself, and had equally predictable climate
effects. As a result, meteorological observation of the QBO
natural-variability pattern enabled forecasters to get an idea of
what weather trend to expect for winter — not just during a single
year, but also over a longer time horizon.
Climate Change May Now Be in the Process of Breaking It
happens if the QBO becomes less predictable due to influences such as
human-forced polar warming? What happens if the big meanders in the
Jet Stream produced by this warming dig down all the way to the
Equator during Northern Hemisphere winters and start to shove at the
upper-level Equatorial wind field, causing the QBO to switch? If that
happens, then a major aspect of Northern Hemisphere winter seasonal
variability will have been fundamentally altered by climate change.
Winter would become less like it is now and more like some
strange, difficult-to-predict, climate-change-morphed hybrid of a
the past decade, scientists like
Dr. Jennifer Francis have
observed strange changes to the Northern Hemisphere Jet Stream.
In winter, the North Pole has tended to exhibit extreme relative
warming versus the rest of the Northern Hemisphere. This warming has
created less difference in temperature from north to south during
this season. As a result, it
appears that the Jet Stream has slowed and is generating very large
atmospheric waves, known
as gravity waves or Rossby waves. At times, these waves have
linked upper-level air flows between the Tropics and the North Pole.
strong polar warming during winter is called polar
an effect produced by climate change. Polar
amplification happens because greenhouse gasses resulting from
fossil-fuel burning (like carbon dioxide and methane) preferentially
trap heat during times of darkness. During December through
March, large sections of the North Pole are blanketed in the dim of
Polar Night. During this time the heat-trapping effects of
these gasses really go to work. Additionally, heat from the
ocean is transferred through the thinning veil of sea ice over the
Arctic Ocean even as local carbon stores add to the overburden of the
heat-trapping gasses already in place. The net effect is a much
warmer-than-normal Arctic during winter. This warming appears to be
doing a serious number on the Jet Stream and, apparently, even
Equatorial atmospheric circulation.
QBO Switch in February 2016
the most recent winter, scientists observed these high-amplitude Jet
Stream waves reaching all the way into the Equatorial upper-level
wind field with enough oomph to switch an east-west wind pattern to
switch was entirely unpredicted and unprecedented.
No one expected it and it has never before been observed.
weather pattern for a big swath of Europe was, as a result, flipped
from the expected cool and dry to warm and wet. If you had told any
atmospheric scientist that such a set of changes would happen, they
might have categorically
claims. But now, some scientists are starting to look at the
possibility that the recent QBO flip was due to a
climate warming-related influence.
pattern of surface warming as provided by the IPCC. Uneven relative
warming of the surface of the Earth may result in some unexpected
changes to larger atmospheric circulation patterns. Scientists now
indicate that future flips in Equatorial wind patterns,like
the big switch that occurred this past winter, may
be driven by such atmospheric warming. Image source: IPCC.)
is a possibility that the recent flip was related to large
atmospheric waves which are potentially a result of polar
amplification. These waves appear to have impacted the
upper-level Equatorial winds, and so are not necessarily related
to natural climate variability.
initiate such a big atmospheric change requires a great deal of
force. The equatorial wind field and atmospheric mass is generally
the heaviest, is typically the region with the greatest atmospheric
inertia. Having an outside influence, like polar warming and
associated gravity waves, generating a flip in its flow is about the
meteorological equivalent to rivers running up hill. Apparently, due
to climate change, atmospheric ‘rivers’ in the Jet Stream may now
be capable of doing just that, and that’s pretty disturbing.