Page 28 - ARUBA TODAY

A28 SCIENCE
Tuesday 16 January 2018

Is warming in the Arctic behind this year’s crazy winter weather?

Jennifer Francis mild month.
Rutgers University Two other important fea-
Damage from extreme tures are conspicuous in
weather events during 2017 the dipole temperature
racked up the biggest-ev- pattern: extremely warm
er bills for the U.S. Most of temperatures in the Arc-
these events involved con- tic near Alaska and warm
ditions that align intuitively ocean temperatures in
with global warming: heat the eastern Pacific. Sev-
records, drought, wildfires, eral new studies point to
coastal flooding, hurricane these “ingredients” as key
damage and heavy rain- to the recent years with a
fall. persistent dipole.
Paradoxical, though, are IT TAKES TWO TO TANGO
possible ties between cli- What role does warming
mate change and the re- – specifically the warming
cent spate of frigid weeks ocean and air tempera-
in eastern North America. tures in the Arctic – play in
A very new and “hot top- this warm-West/cool-East
ic” in climate change re- weather pattern? The ex-
search is the notion that planation goes like this.
rapid warming and whole- Pacific Ocean tempera-
sale melting of the Arctic The ‘bomb cyclone’ freezes a fountain in New York City. tures fluctuate naturally
may be playing a role in Associated Press owing to short-lived phe-
causing persistent cold nomena such as El Niño/La
spells. 2017, and 2018 seems to be miliar one, as similar con- spheric pressure, persisted Niña and longer, decades-
It doesn’t take a stretch following the same script. ditions have played out in off the West Coast along length patterns. Scientists
of the imagination to sup- Most U.S. Easterners shiv- four of the past five winters. with a deep southward have long recognized
pose that losing half the ered their way through the Some politicians in Wash- dip, or a “trough,” over the that those variations affect
Arctic sea-ice cover in only end of 2017 into the New ington D.C., including Presi- East. weather patterns across
30 years might be wreak- Year, while Westerners dent Trump, have used the New terms have been North America and be-
ing havoc with the weath- longed for rain to damp- unusual cold to question coined to describe these yond.
er, but exactly how is not en parched soils and ex- global warming. But if they stubborn features: “The When a persistent area
yet clear. As a research tinguish wildfires. Blizzards looked at the big picture, North American Win- of atmospheric pressure
atmospheric scientist, have plagued the Eastern they’d see that eastern ter Temperature Di- stays in the western U.S., air
I study how warming in the Seaboard – notably the cold spells are a relative pole,” the “Ridiculously Re- from the Arctic pours into
Arctic is affecting temper- “bomb cyclone” storm on fluke in the Northern Hemi- silient Ridge” over the West, the U.S, causing a split be-
ature regions around the Jan. 4, 2018 – while Califor- sphere as a whole and that and the “Terribly Tenacious tween the warm and dry
world. Can we say chang- nia’s Sierra Nevada stand most areas are warmer Trough” in the East. West and the cold East.
es to the Arctic driven by nearly bare of snow. than normal. While the eastern U.S. Mesocyclone2014 and Da-
global warming have had A study in contrasts: Warm- A warm, dry western North suffered very cold tem- vid Swain, CC BY-SA
a role in the freakish win- ing near Alaska and the America occurring in com- peratures in the recent The new twist in this story
ter weather North America Pacific Ocean are ‘ingre- bination with a cold, snowy cold snap, much of the is that the Arctic has been
has experienced? dients’ to a weather pat- east is not unusual, but rest of the Northern Hemi- warming at at least double
A ‘DIPOLE’ OF ABNORMAL tern where cold air from the prevalence and per- sphere saw higher-than- the pace of the rest of the
TEMPERATURES the Arctic plunges deep sistence of this pattern in average air tempera- globe, meaning that the
Weird and destructive into North America. recent years have piqued tures. NOAA, CC BY difference in temperature
weather was in the news NASA Earth Observato- the interests of climate re- Regardless what it’s called, between the Arctic and
almost constantly during ry, CC BY searchers. this dipole pattern – abnor- areas farther south has
This story is becoming a fa- The jet stream – a fast, mally high temperatures been shrinking.
upper-level river of wind over much of the West This matters because the
that encircles the North- along with chilly conditions north/south tempera-
ern Hemisphere – plays a in the East – has dominated ture difference is one of
critical role. When the jet North American weather in the main drivers of the
stream swoops far north four of the past five winters. jet stream. The jet stream
and south in a big wave, January 2017 was a stark creates the high- and
extreme conditions can re- exception, when a strong low-pressure systems that
sult. El Niño flipped the ridge- dictate our blue skies and
During the past few weeks, trough pattern, dumping storminess while also steer-
a big swing northward, record-breaking rain and ing them. Anything that af-
forming what’s called a snowpack on California fects the jet stream will also
“ridge” of persistent atmo- while the east enjoyed a affect our weather.q