year, the periodic Equatorial cooling known as La Nina is again
taking place in the Pacific during fall following a very mild warming
during winter and spring. But despite the appearance of a second such
periodic cooling event, according to NASA 2017 is 94 percent likely
to be the second warmest year ever recorded (see above).
readings have come in and
at 0.9 C above NASA baseline (1.12 C above 1880s averages),
temperatures are disturbingly high. The month is now the second
hottest ever seen by modern humans. With only October of 2015 coming
in warmer at 1.08 C above the 20th Century baseline (1.3 above
transfer into the polar zones is increased during La Nina periods.
This effect is enhanced by polar amplification related to human
caused climate change. This week, very high relative temperature
departures are expected for the Arctic. Image source: Climate
the past two years, La
Pacific) appear to have been at least partly off-set by very strong
warming in the Arctic and Antarctic. Atmospheric circulation tends to
transport more heat into the polar zones as the Pacific cool.
is due to the fact that temperature differential between Equator and
poles during La Nina is less and the lower temperature differential
causes the upper level winds to slow and meander. Coupled with polar
amplification due to human-caused climate change, the result can be
some pretty extreme temperature departures. This week is no exception
as Arctic temperatures by Thursday through Saturday are expected to
be between 4 and 5 degrees Celsius above average for the entire
region above the 66 North parallel.
record warm temperatures do not occur in isolation. They help to
drive extreme weather events such as severe droughts, rainfall, and
powerful hurricanes. They are also accelerating sea level rise by
melting glaciers even as both warming temperatures and related
increasing ocean acidification contribute to dead zones, coral reef
deaths and declining ocean health. Global temperature rise coupled
with rising CO2 is therefore producing a major systemic crisis the