2: Lecture 21: Long- and Short-term Climate Changes Lecture 21: Global Climate Changes aquarium trip 1 (HW7) last day tomorrow aquarium trip 2 (HW8) assignment is (and available here) return HW#6 (to your right) pick up HW#4,5 (to your left) ice hour: Tue, Nov 20 4-5:50 pm York3030 midterm 2 (NOV 30) study guide will be online Nov 23 • return trip1 on TABLE!
Lecture 21: Global Climate Changes. return trip1 on TABLE!. return HW#6 (to your right) pick up HW#4,5 (to your left). office hour: Tue, Nov 20 4-5:50 pm York3030. aquarium trip 1 (HW7) last day tomorrow aquarium trip 2 (HW8) assignment is now online (and available here). - PowerPoint PPT Presentation
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SIO15-12: Lecture 21: Long- and Short-term Climate Changes
Lecture 21: Global Climate Changes
aquarium trip 1 (HW7) last day tomorrow
aquarium trip 2 (HW8) assignment is now online (and available here)
• return HW#6 (to your right)• pick up HW#4,5 (to your left)
office hour: Tue, Nov 20 4-5:50 pm York3030
midterm 2 (NOV 30) study guide will be online Nov 23
• return trip1 on TABLE!
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
Where do Hurricanes Occur? NamingWhere do Hurricanes Occur? Naming
Image: NASA’s Earth Observatory
30%30%15%15%
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hurricanes
hurricanes
typhoons
cyclones
• most hurricanes in W. Pacific (typhoons)most hurricanes in W. Pacific (typhoons)• more hurricanes in E. Pacific than in Atlanticmore hurricanes in E. Pacific than in Atlantic• Indian Ocean: cyclonesIndian Ocean: cyclones
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
• strongest hurricanes in W. Pacificstrongest hurricanes in W. Pacific• no hurricanes in S. Atlanticno hurricanes in S. Atlantic (1 exception: hurricane Catarina, Mar 2004)(1 exception: hurricane Catarina, Mar 2004)• “ “ “ “ “ “ S.E. PacificS.E. Pacific
Location and Frequency of HurricanesLocation and Frequency of Hurricanes
Image: NASA’s Earth Observatory
hurricanes do not hurricanes do not cross equatorcross equator(Coriolis Effect)(Coriolis Effect)
strong cold currentsstrong cold currents
winds unfavorablewinds unfavorable
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
El Nino and Atlantic HurricanesEl Nino and Atlantic Hurricanes
-1997 1997 El NinoEl Nino cooler trop. Atl.cooler trop. Atl. dry summers in West Africadry summers in West Africa- - less Atl. hurricanesless Atl. hurricanes
-1998 1998 La NinaLa Nina warmer trop. Atl.warmer trop. Atl. wet summers in West Africawet summers in West Africa- - more Atl. hurricanesmore Atl. hurricanes
Image: Abbott “Natural Disasters”
SIO15-12: Lecture 21: Long- and Short-term Climate Changeshttp://en.wikipedia.org
sustained winds: 185mph gusts: 220mph pressure: 902 mbar no landfall but hit Socorro Island no fatalities but $3.2Mio Damage
1997: Cat 5 Hurricane Linda(strongest ever recorded in E.P.)
Hurricanes close to home (Baja California)Hurricanes close to home (Baja California)
cut power to met. station on Socorroclosed resorts in Bajaflooding in mainland Mexico15ft surge in So. Cal.5 people swept off jetty in Newport Beachsevere flooding and mudslides in So. Cal.(destroyed 2 houses, damaged 77)
Linda and Mainland
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
no hurricane ever made landfall in So. Cal. landfall of a tropical storm in 1939 ($ 2Mio damage) some came into SW but made landfall somewhere else
meteorological records don’t go back very far newspaper accounts -> Oct 2 1858 San Diego Hurricane from winds speeds and pressure -> category 1/F2 winds ships blown ashore house completely destroyed 1860 population of New San Diego county: 4325
Damage if such a hurricane would strike today: several $100Mio
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
Hurricanes in Southern California?Hurricanes in Southern California?
from: Marshak “The Earth: Portrait of a Planet”
HURRICANESHURRICANES- need warm water to grow/sustainneed warm water to grow/sustain- cold California Current protects uscold California Current protects us- “ “no hurricane has ever made landfall in SoCal”no hurricane has ever made landfall in SoCal”- global warming could shift currents
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
….why do we have to know?...
“hurricanes over Scotland;new ice age over a few weeks”
ONLY IN HOLLYWOOD (2004) BUTNEVERTHELESS WORTH WATCHING
Long- and Short-term Climate ChangesLong- and Short-term Climate Changes
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
Recent Temperature and Atmospheric CORecent Temperature and Atmospheric CO22
• T has increased nearly exponentially in last 50 years• rate not seen in previous 950 years• proxies: tree rings, pollen counts, etc
Why do we care about this in a natural disasters class?• climate changes can happen rapidly (over several years)• clues of what to expect may lie in past
current CO2 changing dramatically
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
+ other stuff-CO2 353ppm (0.0353%) (1992); 391 ppm (2012)- Ne 18ppm- He 5ppm- CH4 2ppm- Kr 1ppm- H2O variable (water vapor)
Before Life Now
- before life: mainly CO2
- today: mainly N2 and O2Greenhouse Gases: CO2, CH4, H2O
Greenhouse effect: see Lecture 15
Review: Composition of Earth’s AtmosphereReview: Composition of Earth’s Atmosphere
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
-recent long-term trend is coolingrecent long-term trend is cooling-Earth was mostly warmer than today!Earth was mostly warmer than today!-glaciation very rareglaciation very rare
-colder periods tend to be driercolder periods tend to be drier
Climate over TimeClimate over TimeT and PrecipitationT and Precipitation
Cretaceous: a lot warmer than today Cretaceous: a lot warmer than today --> 3 times more CO--> 3 times more CO22????????
current long-term trend: COOLING
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
Changes in Global Sea LevelChanges in Global Sea Level
Sea level has changed by many 100m over time
• lower sea level during glaciationlower sea level during glaciation• higher sea level in warm periodshigher sea level in warm periods• sea level dropped by 200m in last 10 Mio yrssea level dropped by 200m in last 10 Mio yrs
sea level also depends on sea floor spreading!!sea level also depends on sea floor spreading!!--> cannot infer T directly!!-> cannot infer T directly!!
SIO15-12: Lecture 21: Long- and Short-term Climate Changes
recent short-term trend: WARMING
Short-Term Changes (1000s of years)Short-Term Changes (1000s of years)
- short-term changes NOT cause by plate tectonics
possible causes:• Milankovich cycles• change in solar output• volcanism• ocean currents