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Mangled
Jet Stream Swings to Hot Over UK: New Weather Emergency Brings Killer
Heatwave, Wildfires
This
winter the UK weather news was snow, storms and cold. This spring the
news was cold, rain and flooding. Now, the news is deadly record
heatwave.
Over
the past week, the UK has baked under record high temperatures
ranging from the high 80′s and into the low 90′s (Fahrenheit).
These record temperatures, the highest since 2006 (which was the
hottest in 350 years), are implicated in the deaths of nearly 800
persons, have buckled roads and tennis courts alike, set off dozens
of wildfires that have taken hundreds of firefighters to contain, and
threatened thousands of square miles of UK croplands.
The
heat is expected to continue for portions of England, Scotland and
Ireland this week with some forecasters calling for the potential of
100 degree (F) temperatures across the region. Forecasts also show
the potential for severe thunderstorms with an increased threat of
lightning and localized flash floods emerging.
Though
other regions of the world often experience temperatures hotter than
those seen over the UK throughout the past week, the UK has very few
buildings equipped with air conditioning, as daytime temperatures
only rarely rise into the 80s. So the young, the elderly and this
sick are more vulnerable when high temperatures do arrive as they are
both not acclimated to heat and lack access to indoor cooling systems
that, in cases like these, can be life-savers.
Mangled
Jet Stream Delivers Extremes Yet Again
A deep Rossy-Wave type dip in the Jet Stream that had extended from Greenland, across the North Atlantic and into the UK and Western Europe this winter and spring, bringing cold weather, record snow and rainfall, and extraordinarily stormy conditions, slowly collapsed over late June and early July. Then, last week, a large bulge and related heat dome high pressure system began to form. As the bulge extended far north toward Greenland, Iceland and Svalbard, temperatures over the UK built until a record heatwave began to scorch the region.
So,
in this area, the
cold and wet winter extremes that caused the UK Met Office to call an
emergency meeting on climate change
has been replaced by deadly heat, dryness and wildfires.
The
underlying causes of these extremes is likely a great weakening of
the Jet Stream’s flow over the Northern Hemisphere. According to
researchers, the Jet Stream has slowed down by at least 14% since the
1990s. This slowing down has caused the Jet Stream to act like a
lazily flowing river creating great north-to -outh and south-to-north
loops and meanders. These large meanders bring cold, wet and stormy
conditions when they flow from north to south, as happened over
Europe for much of this winter and spring. The south-to-north flows,
conversely, bring hot, dry conditions that increase the risk of
droughts, wildfires and heatwaves.
Driving
these new extremes, according to the research of climatologists like
Dr. Jennifer Francis at Rutgers, is a massive, global warming driven
erosion of snow cover and sea ice in the Arctic. Since 1979 sea ice
volume has dropped 80% while sea ice extent has fallen 50%. Over past
years, summer snow cover has also hit new record lows. The loss of
ice creates Arctic weather conditions that are many degrees warmer
than average. This response, is a result of the elimination of cold,
reflective snow and ice cover that turns back the sun’s heating
rays. Areas devoid of ice and snow cover instead absorb more of the
sun’s light and heat. The result is that the difference in
temperature between high lattitudes and lower lattitudes is much
lower.
Since
large differences between hot and cold temperatures are the primary
driver for Earth’s Jet Stream, the speed of air flow is now slowing
down as the north pole warms faster than the temperate and tropical
regions. And these changes help to drive increasing instances of
extreme weather. In the UK, it resulted in an extreme winter and
spring (cold rain and snow) followed by an extreme July (heatwaves,
hot temperatures, dryness, fires).
Dr.
Jennifer Francis provides an excellent explanation of these
conditions in the following video:
Sadly,
the UK is not the only location to have experienced deadly and
extreme weather this year. Weather Underground provides a long and
growing list of damaging weather events for 2013. And this list
includes many events such as floods, extreme winter conditions, and
heat waves that can all be tied to new extreme patterns of the
Northern Hemisphere Jet Stream.
1)
Flooding, Central Europe, 5/30 – 6/6, $22 billion
2) Drought,
Brazil, 1/1 – 5/31, $8.3 billion
3) Tornado, Moore, OK, and
associated U.S. severe weather, 5/18 – 5/22, $4.5 billion
4)
Drought, Central and Eastern China, 1/1 – 4/30, $4.2 billion
5)
Flooding, Calgary, Alberta Canada, 6/19 – 6/24, $3.8 billion
6)
Flooding, Indonesia, 1/20 – 1/27, $3.31 billion
7) Flooding,
Australia, 1/21 – 1/30, $2.5 billion
8) Tornadoes and severe
weather, U.S., 5/26 – 6/2, $2 billion
9) Severe weather, Midwest
U.S., 3/18 – 3/20, $2 billion
10) Winter weather, Europe, 3/12 –
3/31, $1.8 billion
11) Drought, New Zealand, 1/1 – 5/10, $1.6
billion
12) Flooding, Sichuan Province, China, 7/7 – 7/11, $1.6
billion
13) Flooding, China, 6/29 – 7/3, $1.4 billion
14)
Flooding, Argentina, 4/2 – 4/4, $1.3 billion
15) Flooding, India
and Nepal, 6/14 – 6/18, $1.1 billion
16) Winter weather, Plains,
Midwest, Northeast U.S., 2/24 – 2/27, $1.0 billion
And
now we can tentatively add:
17)
Heatwave, drought UK 7/13-?, $xxxx?
The
UK swing from extreme cold, snow, rain and flooding to extreme heat
and dryness over the course of about 7 months is a perfect example of
the new types of weather extremes human caused climate change is
driving. We are just at the beginning of these changes so,
unfortunately, conditions should continue to worsen, especially if we
fail to provide proper mitigation rapidly cutting human greenhouse
gas emissions.
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