Global Change Impacts: SE U.S. Weather

1
Global Change ImpactsSE U.S. Weather
Climate Judith Curry Georgia Institute of
Technology
2
The hockey stick curve (IPCC, 2001)
Mann et al. (1999)
Global surface temperatures for the last 100
years are unprecedented in the last millennia
3
Attribution of warming from climate model
experiments
Meehl et al, 2004 J. Climate.

• Warming after 1970 is attributed
  to greenhouse gases

4
Impacts of global warming on SE U.S. weather
climate

• Increase in mean surface temperature
• More severe and longer lasting droughts
• Sea level rise
• Increased hurricane activity

5
Sea surface temperature in global tropics
0.50.25ºC
Increase of 1oF in global tropical SST
since 1970
6
Global increase in hurricane intensity Webster,
Holland, Curry, Chang, Science, 9/16/05
of cat 45 hurricanes has doubled globally
since 1970
7
Relationship between of Atlantic storms and
sea-surface temperature
1oF increase in temperature -- 5 tropical storms
8
Atlantic multidecadal oscillation (AMO)
---------------------------- ------------------
------------ -----
SST
TS
AMO quasiperiodic peaks 1880, 1950, (2020) ABO
minima 1935, 1955, 1975, 1995, (2015) AGW
global warming trend since 1970
9
Peak Periods of N. AtlanticHurricane Activity
1945-1955 1995-2005 Tropical storms
115 165 Hurricanes 74
112 Category 345 41 45
Category 45 19 28
10
2005 Atlantic Hurricane Records
Total named storms 28 (21) Hurricanes
15 (12) Category 5 storms 4
(2) Strongest storm 185 mph (Wilma) Total
damages US 200B
o
11
2005 season Five Gulf Category 4-5 storms
http//weatherunderground.com/tropical
12
Hurricane Katrina
Sea surface temperature
Depth of warm layer
Hurricane Katrina intensified when it crossed the
warm, deep Loop Current
R. Scharoo
13
Systematic lengthening of the North Atlantic
hurricane season
Since 1915, there is an increase of 4.8
days/decade
1851-2005, 10 yr running mean
14
U.S. Landfalling Hurricanes
1851-2004, 10 yr running mean
SST
P. Agudelo
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
100 mph
120 mph
160 mph
140 mph
20
TC-Induced Tornado Climatology
Hurricane-induced tornadoes NE quadrant is
preferred location for tornadoes Optimum range
for tornadoes is 120-240 miles from eye 87 of
all hurricane-induced tornadoes assoc. with
landfall in the Gulf

• NE Quadrant is preferred location ambient
  helicity is maximized (Novlan and Gray
  1974)(McCaul 1991)
• 74 of post-landfall tornadoes reported from
  1964 to 1983 were associated with outer-band
  convection (Weiss 1987)
• Optimum range for outer-band tornadoes is 120 to
  240 miles from the center of the TC (Spratt et
  al. 1997)
• 87 of all tornado-producing TC make landfall in
  the Gulf rather than the Atlantic (Hagemeyer and
  Hodanish 1995) .

21
Why are TC-Induced Tornadoes Important?
Tornadoes can occur several days after landfall

• 2. Tornadoes can occur several days after
  landfall.

Hurricane Ivan made landfall in Gulf Shores, AL
at 150 a.m. 9/16/04. The last tornado occurred
49 hours later, 1000 mi from initial landfall.
Hurricane Ivan made landfall in Gulf Shores,
AL at 150 am on 09/16/04. The last tornado
occurred 49 hours after landfall 1,000 mi
from landfall!
22
Risks to Georgia

• 3 landfalls since 1851 (but none since 1900) but
  substantial
• increases in the number of storms increases
  the probability
• of a GA landfall
• Landfall on GA coast has potential for big storm
  surge
• owing to shallow shelf
• Barrier islands at extra risk associated with sea
  level rise
• Heavy rainfall associated with storms that make
  landfall
• in the Gulf
• Tornadoes likely to be spawned in GA by intense
  storms that
• make landfall in the Gulf this will become
  more likely as
• storm intensity increases and a higher
  proportion of storms
• enter the Gulf