these factors pointed toward a climate system that should have been
pulling the world into a cyclical short term cooling during 2017 and
2018 (relative to 2016 record warmth). Global temperatures under such
conditions would have been expected to recede about 0.1 to 0.2 C off
highs hit during 2016 of 1.2 C hotter than 1880s temperatures.
Averaging in a still disturbingly warm range near 1 C above 1880s
values but waiting for the next El Nino cycle for a run at new global
Heads Toward the Poles
so far, the expected cyclical cooling isn’t happening.
of 2017 showed up as 1.14 C hotter than 1880s while February was 1.32
The combined average of these two months was 1.23 C warmer than the
preindustrial baseline — or a hair warmer that
the 2016 average. This shouldn’t have happened. But it did. And now
there is some risk that 2017 may be yet another record hot year. The
fourth in a row consecutively.
what was the cause?
saw highest above average temperature readings centered near the
poles — a signal that polar warming was the primary factor driving
near record heat for the month. Image source: NASA.)
Amplification Appears to Drive Weird 2017 Warmth
strong warming at the poles is indicative of a
global warming related condition called polar amplification.
The causes of polar amplification include increasing water vapor at
the poles, high greenhouse gas overburdens in the Arctic, a darkening
of the polar ice from particulates (wildfire and human-produced
smoke), intensification of transport of heat from the lower and
middle latitudes toward the poles, warming oceans and changes in
ocean circulation, and loss of snow and ice cover at the poles. To
this final point, sea ice coverage has been consistently at or near
record lows for both the northern and southern polar regions.
sea ice extent at record lows likely helped to contribute to
extremely warm conditions at the poles during February of 2017. Less
sea ice means more water vapor evaporating from oceans in the polar
regions. Water vapor is a powerful greenhouse gas. In addition,
warmth from the ocean can more readily ventilate into local
atmospheres which aids in heat transport to the polar regions as the
skein of sea ice retracts. Image source: Wipneus.
Data Source: NSIDC.)
amplification is not typically cited as a climate event that can
overcome the transient cooling signal of a post El Nino period.
However, given a first look at the evidence, this appears to be
exactly what happened during early 2017. If this is the case, it is
cause for serious concern. It is an indicator that a global tipping
point has been reached in that warming at the poles (which is an
upshot of the ridiculously high greenhouse gas levels we now see
globally) is strong enough to drown out some of the traditional ENSO
and PDO signals.