Global warming and severe weather: hurricanes

Hurricanes and global warming

• More hurricanes– Warming SST’s (sea surface temperatures) suggest

greater source of energy for hurricanes, hence they should be more frequent

N. Atlantic hurricane record best after 1944 with aircraft surveillance.

SST(1944-2005)

Hurricanes and global warming

• Fewer hurricanes– Increased wind shear – Increasing atmospheric stability

La Nina

Drawing

El Nino

Drawing/animation

Southern Oscillation and global warming

• ENSO not caused by global warming

• ENSO is natural cycle

• More El Nino conditions under global warming

Source of uncertainties

• Small sample size (only a few hurricanes each year)

Early view of hurricane structure, 1946

Radar-based hurricane tracking, 1960

http://weather.unisys.com/hurricane/atlantic/index.html

Source of uncertainties

• Difficult to separate natural and anthropogenic influences on the conditions leading to hurricane development

Source of uncertainties

• Different ways to quantify hurricane activity?– Strength?– Frequency?– Duration of season?– Tracks?