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SUMMARY:Arctic climate change – mid latitude circulation and extreme wea
 ther linkages - Prof Dr E. Hanna
DTSTART:20170321T140000Z
DTEND:20170321T150000Z
UID:TALK70487@talks.cam.ac.uk
CONTACT:Dr Alexandra Weiss
DESCRIPTION:Amplified warming has recently occurred in the Arctic and is l
 inked with dramatic declines in Arctic sea-ice and mass loss of the Greenl
 and Ice Sheet. At the same time\, over the last decade\, there has been a 
 notable clustering of extreme weather events in the Northern Hemisphere mi
 d-latitudes\, which in the UK (and wider north-west Europe) has included a
 t times record cold/snowy winter weather\, and at other times unusually we
 t\, stormy winters\, as well as some record wet summer spells. Unusually c
 old and snowy winter weather was also often seen in the eastern US and in 
 Siberia\, while Greenland experienced record warmth in summer 2012\, leadi
 ng to a record surface melt and mass loss of its ice sheet. In the UK and 
 wider Northwest Europe there has been a notable increase in the year-to-ye
 ar variability of winter weather conditions over the last few decades (som
 etimes cold and snowy\, sometimes wet and stormy)\, which reflects an stri
 king shift in the atmospheric polar jet stream over the North Atlantic. In
  summer there has been a significant increase in high-pressure blocking ov
 er Greenland in the last 10-20 years\, which is linked to a more southerly
  average jet-stream flow. This lecture will explore how these recent chang
 es in Arctic climate and extreme weather further south may be linked throu
 gh jet-stream changes. There is a tendency at times for a more amplified (
 north-south waving) jet-stream flow\, which encourages greater exchanges o
 f air masses between mid and high latitudes and is sometimes related to mo
 re stationary and persistent mid-latitude weather patterns. Continued glob
 al warming through human-enhanced greenhouse gases will most likely spring
  further surprises. Therefore we will conclude by exploring how mid-latitu
 de extreme weather may respond to continued Arctic climate change during t
 he rest of the Twenty First Century.
LOCATION:British Antarctic Survey\, Room 187
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