Kerry Emanuel Lorenz Center Department of Earth Atmospheric and Planetary Sciences MIT Program Overview of hurricanes Basic theory of hurricanes What have hurricanes been like in the past and how will they be affected by global warming ID: 1021317
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1. Are We Affecting Hurricanes?Kerry EmanuelLorenz CenterDepartment of Earth, Atmospheric, and Planetary Sciences, MIT
2. ProgramOverview of hurricanesBasic theory of hurricanesWhat have hurricanes been like in the past, and how will they be affected by global warming?
3. Brief Overview of Tropical Cyclones
4. What is a Hurricane?Formal definition: A tropical cyclone with 1-min average winds at 10 m altitude in excess of 32 m/s (64 knots or 74 MPH) occurring over the North Atlantic or eastern North Pacific
5. The word Hurricane is derived from the Mayan word Huracan and the Taino and Carib word Hunraken, a terrible God of Evil, and brought to the West by Spanish explorers
6. God of Winds Temple, Tulum, Mexico
7. The View from Space
8. Igor, 2010
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11. Tropical Cyclone Climatology
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13. Annual Cycle of Tropical Cyclones Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec NH Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun SHaaNorthern Hemisphere(NH)Southern Hemisphere(SH)Number of Events per Month
14. Basic Theory: Implications for Hurricane and Climate Change
15. Energy Production
16. Theoretical Steady-State Maximum Hurricane Wind Speed:Air-sea enthalpy disequilibrium of moist static energySurface temperatureOutflow temperatureRatio of exchange coefficients of enthalpy and momentum
17. Annual Maximum Potential Intensity (m/s)
18. What Can We Learn from Past Hurricanes?
19. barrier beachbackbarrier marshlagoonbarrier beachbackbarrier marshlagoona)b)Source: Jeff Donnelly, WHOIuplanduplandflood tidal deltaterminal lobesoverwash fanoverwash fanPaleotempestology
20. Jeffrey P. Donnelly and Jonathan D. Woodruff, Nature, 2007
21. Storm Maximum Power Dissipation and SSTNorth Atlantic
22. Sulfate Aerosols and North Atlantic Hurricanes During the late 20th Century, global aerosol radiative forcing is thought to be as important as CO2 radiative forcing Per unit radiative forcing, shortwave forcing is roughly twice as effective as longwave forcing in changing potential intensity Much of the interannual variability of aerosol forcing over the tropical North Atlantic in summer is thought to be owing to the interaction of sulfate aerosols of European origin with African dust
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24. Storm Maximum Power Dissipation and SSTNorth Atlantic
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26. Does Global Warming Affect Hurricanes?
27. Svante Arrhenius, 1859-1927“Any doubling of the percentage of carbon dioxide in the air would raise the temperature of the earth's surface by 4°; and if the carbon dioxide were increased fourfold, the temperature would rise by 8°.” – Världarnas utveckling (Worlds in the Making), 1906
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30. How Does Potential Intensity Change with Climate?
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32. Trends in Thermodynamic Potential for Hurricanes, 1980-2010(NCAR/NCEP Reanalysis)ms-1decade-1
33. Projected Trend, 2006-2100: GFDL model RCP 8.5 ms-1decade-1
34. Time series of the latitudes at which tropical cyclones reach maximum intensity.From Kossin et al. (2014)
35. Projections of Future Hurricane Risk
36. Hurricane Risks:WindStorm SurgeRain
37. Approach:Embed highly detailed computational hurricane models in large-scale conditions produced by climate models
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40. Hurricanes Passing within 150 km of BostonDownscaled from 5 climate models
41. Surge Risk
42. Rain Risk
43. Summary The weight of existing evidence supports the conclusion that unmitigated climate warming presents significant risk to future generations Scientific uncertainty about the nature and magnitude of climate change entails a low but not tiny risk of catastrophic outcomes Among the myriad risks posed by climate change are changes in extreme events, including hurricanes There is now a strong consensus that the frequency of high category events should rise, producing a greater number of storms (like Haiyan) that exceed empirical tolerance levels
44. There is also a strong consensus that tropical cyclone rainfall and associated flood hazards will increase with temperature Increased high category events coupled with sea level indicate a strong risk of increased storm surge hazard