Global Change Impacts:Global Change Impacts:SE U.S. Weather & ClimateSE U.S. Weather & Climate

Judith Curry Judith Curry Georgia Institute of TechnologyGeorgia Institute of Technology

The “hockey stick” curve (IPCC, 2001)

Global surface temperatures for the last 100 years are unprecedented in the last millennia

Mann et al. (1999)

Attribution of warming from climate model experiments

Attribution of warming from climate model experiments

Warming after 1970 is attributed to greenhouse gases

Meehl et al, 2004: J. Climate.

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

a) Increase in mean surface temperature

b) More severe and longer lasting droughts

c) Sea level rise

d) Increased hurricane activity

0.5±0.25ºC

Sea surface temperature in global tropicsSea surface temperature in global tropics

Increase of 1oF in global tropical SST since 1970

Global increase in hurricane intensity

Webster, Holland, Curry, Chang, Science, 9/16/05

# of cat 4+5 hurricanes has doubled globally since 1970

Relationship between # of Atlantic storms and

sea-surface temperature

1oF increase in temperature --> +5 tropical storms

SS

T (°C

)

26.8

26.9

27.0

27.1

27.2

27.3

27.4

27.5

27.6

27.7

27.8North Atlantic Tropical Storms and SST

1845 1865 1885 1905 1925 1945 1965 1985 2005

Ann

ual f

requ

ency

4

5

6

7

8

9

10

11

12

13

14

15

SST

TS

AMO: quasiperiodic peaks 1880, 1950, (2020)ABO: minima 1935, 1955, 1975, 1995, (2015)AGW: global warming trend since 1970

|----------------------------| |------------------------------| |-----Atlantic multidecadal oscillation (AMO)

Peak Periods of N. AtlanticHurricane Activity

1945-1955 1995-2005

#Tropical storms 115 165

# Hurricanes 74 112

# Category 3+4+5 41 45

# Category 4+5 19 28

2005 Atlantic Hurricane Records

oTotal named storms: 28 (21)

Hurricanes: 15 (12)

Category 5 storms: 4 (2)

Strongest storm: 185 mph (Wilma)

Total damages: > US $200B

http://weatherunderground.com/tropical

2005 season:

Five Gulf Category 4-5 storms

Hurricane KatrinaSea surface temperature Depth of warm layer

Hurricane Katrina intensified when it crossed the warm, deep Loop Current

R. Scharoo

Systematic lengthening of the

North Atlantic hurricane season

1851-2005, 10 yr running mean

Since 1915, thereis an increase of4.8 days/decade

U.S. Landfalling Hurricanes 1851-2004, 10 yr running mean

P. Agudelo

SST

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100 mph 120 mph

140 mph160 mph

TC-Induced Tornado Climatology

• 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) .

Hurricane-induced tornadoes

NE quadrant is preferred locationfor tornadoes

Optimum range for tornadoesis 120-240 miles from eye

87% of all hurricane-inducedtornadoes assoc. with landfall in the Gulf

2. Tornadoes can occur several days after landfall.

** Hurricane Ivan made landfall in Gulf Shores, AL at 1:50 am on 09/16/04. The last tornado occurred ~ 49 hours after landfall & ~ 1,000 mi from landfall!

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

Hurricane Ivan made landfall in Gulf Shores, AL at 1:50 a.m. 9/16/04.The last tornado occurred 49 hours later, 1000 mi from initial landfall.

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

Risks to Georgia