March 5, Are Weather Patterns Becoming More Volatile? MMRMA 2015 Risk Management Workshop

Transcription

1 Are Weather Patterns Becoming More Volatile? MMRMA 2015 Risk Management Workshop Josh Darr Meteorologist and VP Catastrophe Risk Management GLOBAL TEMPERATURES SINCE 1880 EARTH TEMPERATURE RECORDS SINCE OF 14 WARMEST YEARS SINCE 2000 Source: Bloomberg Visualization 1

2 NASA Earth Observatory SEASONAL TEMPERATURE TRENDS NORTHERN HEMISPHERE POPULATION ZONES Jun-Aug Sep-Nov Dec-Feb Mar-May 0.46 C/10 Yrs 0.54 C/10 Yrs C/10 Yrs 0.13 C/10 Yrs Tang et. al (2014) Env Res Let: Cold winter extremes in northern continents linked to Arctic sea ice loss SEASONAL TEMPERATURE TRENDS NORTHERN HEMISPHERE POPULATION ZONES N. Hemi N. Amer Europe East Asia C/10 Yrs C/10 Yrs C/10 Yrs C/10 Yrs Cheung et. Al ( ) Hong Kong Observatory: Interdecadal Variability of High Latitude Blocking and Impact East Asian Monsoon 2

3 THE CHANGING ARCTIC CLIMATE SURFACE TEMPERATURE TRENDS NASA WINTER IS A UNIQUE SEASON LAND COOLING WHILE ARCTIC BASIN WARMING Mudryk et. al (2013) Clim. Dynamics: Interpreting observed N. Hemisphere snow trends with large ensembles of climate simulations. ICE DECREASING, SNOW INCREASING LAND COOLING WHILE ARCTIC BASIN WARMING Buffalo, NY November 2014 Liu et. al (2012) Pro Nat l Acad Sci: Impact of declining Arctic sea ice on winter snowfall Open Arctic ocean triggers Arctic sea effect snow similar to lake effect snow belts of the Great Lakes 3

4 WHY IS THE ARCTIC LOSING ICE? FIRST YEAR VS. MULTI YEAR ICE NASA WHAT HAS TRIGGERED ICE LOSS? INCREASED BLACK SOOT/CARBON ON ARCTIC ICE CAP Sharma et. al Arctic Report Card (2013) Black Carbon in the Arctic RECENT CHANGE OR LONG TERM TREND? 1960 TO 2013 VS 1990 TO 2013 TEMPERATURE TRENDS Cohen et. al (2014) Nature Geosciences: Recent Arctic amplification and extreme mid-latitude weather 4

5 ARCTIC/NORTH ATLANTIC OSCILLATION MEASURING THE STRENGTH OF THE POLAR VORTEX NASA DECREASING JET STREAM STRENGTH LOSS OF ARCTIC SEA ICE 20% decrease in strength jet stream movement since % loss in Arctic ice extent since 1990 Arctic has warmed by 2 C since 1990 Francis & Vavrus (2015) Env Res Lett: Evidence for a wavier jet stream in response to rapid Arctic warming ARCTIC AMPLIFICATION THE DRIVER? Arctic Amplification: Arctic warming faster than other areas of globe Jet stream moves slower, has higher amplitude and persists longer Possibility of high impact event within longer periods of persistent weather patterns Global climate models have failed to capture this impact Climate model projections too warm across mid-latitudes in winter 5

6 IS THE CHANGING JET STREAM BEHAVIOR ALTERING THE DISTRIBUTION OF WEATHER RISK? THE POLAR VORTEX PLAYS A STRONG ROLE IN WEATHER/CLIMATE The Polar Vortex setup Sun sets across Arctic as autumn progresses due to tilt of the earth Darkness falls over the Arctic region and cold air builds Strong winds increase to great depth in atmosphere defining the boundary between polar air and mid-latitude/tropical air If nothing disrupts this process, strong Polar Vortex forms over Arctic by late November into December: +AO/+NAO regime earth.nullschool.net Strong and Stable Polar Vortex in Stratosphere THE POLAR VORTEX PLUNGE OF JANUARY 2014 Stretched Polar Vortex Major Cold Air Outbreak Polar Pig 6

7 WINTER OLD MAN WINTER RETURNS Michigan 3rd coldest winter in 120 years Second highest ice extent on record for Great Lakes East coast cities 2nd snowiest on record (snowiest 2010/11) Meanwhile, record warmth and drought in California Stark contrast to two winters before 2011/12 INCREASE IN HEAVY PRECIPITATION EVENTS SIGNIFICANT INCREASE IN GREAT LAKES REGION PRECIP Percent Change in Annual Rainfall vs Frequency of Extreme 2-Day Rainfall Events Relative to Average Change in Amount of Precipitation Falling in Heaviest 1% of all Daily Events Data: National Climactic Data Center National Climate Assessment MORE RAIN BUT LOWER LAKE LEVELS? TEMPERATURE VS. RAINFALL INFLUENCE ON LAKE HEIGHT 582 Lake Michigan/Huron Water Levels Lake Height (feet) Data: NOAA Great Lakes Environmental Research Laboratory 7

8 WETTER GREAT LAKES REGION MORE FREQUENT DROUGHTS WESTERN US ANNUAL TORNADO COUNT EF0 AND GREATER TORNADOS 2000 Annual Tornado Count: EF1 and Greater Number of Tornadoes EXTREME YEAR ON YEAR TORNADO ACTIVITY DETREND HISTORICAL DATA 8

9 LATEST RESEARCH ON TORNADO ACTIVITY LOWER # TORNADO DAYS, HIGHER # SEVERE OUTBREAKS Increase in Large Outbreak Days Days with 30 or more tornados increase tripled since 1960s/70s 20% of all tornadoes occurred on biggest three tornado days of the year, long term average 10% Decrease in EF-1 or Higher Days 150 average # days per year in the 50s/60s 100 average # days per year in last 15 years Increase in Month-to-Month Variability Since 1950, 6 record high months and 5 record low months seen since 2000 Tornado Outbreak Regions Unchanged No shift seen in areas of country most favored for major outbreaks (see map to right) Elsner & Jagger (2014): Increasing Efficiency of Tornado Days, Climate Dynamics 25 QUIET SEVERE STORM YEAR IN 2014? NOT IN NEBRASKA JUNE 3, 2014 Research in weather data and claims suggests significant increase in severity of hail and resulting claims 2007-present versus any other period of record dating to the 1970s Hail Swath/Size for Nebraska June 3, hail reports in Nebraska on June 3, 2014 Prior record: 73 reports on June 1, 2010 RECORD LENGTH NO MAJOR HURRICANES LAST MAJOR HURRICANE LANDFALL WILMA last major hurricane landfall, 3,200+ days ago Last record stretch Return Period of Category 3 or Higher Landfall Only 2 years of the past five (10-14) had a landfall, tying for lowest five year period in history of landfalling hurricanes 9

10 RECENT UPTICK IN NUMBER OF LARGE STORMS KATRINA VS. SANDY Hurricane Katrina 2005 Hurricane Sandy 2012 Sandy generated higher storm surge across a broader area than any other storm in the Atlantic basin 28 RECORD 9-YEAR LULL IN MAJOR HURRICANES BUT 2 OF 5 MOST COSTLIEST HURRICANES $50.0 $45.0 $40.0 $35.0 $30.0 $25.0 $20.0 $15.0 $10.0 $5.0 $0.0 $4.4 Irene Hurricane Sandy became the 3rd costliest hurricane in US insurance history 10 of the 12 most costly hurricanes occurred over the past 9 years $5.6 $5.5 $6.5 $7.0 Jeanne Frances Rita Hugo $8.5 $8.9 Ivan Charley $11.9 Wilma $13.3 Ike $18.8 Sandy $23.3 Andrew $ Katrina CHANGING JET STREAM BEHAVIOR IS IT ALTERING THE DISTRIBUTION OF WEATHER RISK? Likely Weather events seen more frequently in both sides of the distribution of historic outcomes Why is this happening? Natural ocean and atmosphere cycles Warming Arctic altering jet stream Human influence? How to manage it? Long term view is critical and understanding source of trends Pattern persistence and consideration of aggregation of events over a season/year Catastrophe risk analytics - Scenario events - Probabilistic analyses - Catastrophe modeling 10