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Abnormal Fall Arctic Warmth Intensifies; September 2016 Probably Another Record Hot Month Globally
3
October, 2016
“Polar
amplification”
usually refers to greater climate
change near
the pole compared to the rest of the hemisphere or globe in response
to a change in
global climateforcing,
such as the concentration of greenhouse gases
(GHGs)…
Real Climate [emphasis
added]
*****
It’s
fall. The Arctic is trying to cool down, but what would typically be
a steady decline into frigid temperatures is being held back by the
increasingly strong hand of human-forced climate change.
(Over
recent weeks, temperature departures above the 1958-to-2002 average
line [green line above] have grown in the region north of the 80th
parallel. In general, the Arctic has experienced much warmer than
normal temperatures. Failure of the Arctic to rapidly cool down
during fall has been a feature of recent years that is related to
human-forced climate change. Image source: DMI.)
Over
the past month, temperature anomalies for the entire Arctic have
ranged near 3 degrees Celsius or more above average. These
temperatures appear to have represented the highest departures from
average for any world region for the past month. Overall, they’ve
greatly contributed to
what is likely to be another record hot month globally.
Into
the first week of October, this trend is expected to intensify. By
Friday, according to GFS model runs, temperatures above the 66°
North Latitude line are expected to range near 4.5 C (8 degrees
Fahrenheit) above average for the entire region. Meanwhile, areas of
Greenland, the Arctic Ocean and Northeastern Siberia are expected to
see 10-18 C (18 to 32 F) above-average temperature departures for the
day.
(Extreme
Arctic heat is likely to lead record-high global temperatures for the
month of September. Such heat is also likely to help push October
into top 3 record-hot month ranges. Image source: Climate
Reanalyzer.)
It
doesn’t need to be said that these are extraordinary warm
temperature departures from normal, which represent near-record or
record warm ranges for many locations, but this is what we would
expect with human-forced climate change. As the sun falls in the
Arctic sky and night lengthens, energy transfer in the form of heat
coming in from the warming ocean and atmosphere intensifies. This
effect is driven by what is now a great overburden of greenhouse
gasses in the Earth’s atmosphere.
Early
Indicators Point Toward a Record-Hot September
Powerful
heat transfers slowing down the rate of fall cooling in the Arctic
came amid what is likely to be the hottest September in the global
climate record.
Translated to NASA GISS figures, if they were to match this increase,
September values would fall around 1.03 C hotter than NASA’s
20th-century baseline and about 1.25 C hotter than 1880s averages.
(August
2016 was the hottest month on Earth in all of the past 136 years.
Though the Earth is cooling into fall, September 2016 looks like it
will be the hottest September ever recorded. Overall, 2016 is on
track to be the hottest year on record by a significant margin. Image
source: Earth
Observatory.)
Temperatures
in these ranges would represent the hottest September on record by a
pretty big margin (about 0.13 C globally). Meanwhile, the annual
averages for the first nine months of the year would hit near 1.27 C
above 1880s averages if the NASA measure saw a warming similar to
that showing up in Stokes’s early NCEP/NCAR
reanalysis figures —
a measure disturbingly close to the 1.5 C departure levels that
represent the first major global climate threshold, a level that many
scientists have advised us we’d be wise to avoid.
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