ors 1360 Planet Earth me: osphere: Milankovitch Cycles: Summer insolation at high northern latitudes controls glacial/interglacial cycles Should see strong correlation between hi-N-lat summ insolation and global temperature Nope. But transitions occur when insolation is changing in the right direction, and power in orbital periods indicates they are related! So there must be something else going on too… CO 2 and palaeotemperature proxy 18 O strongly correlate Temperature changes first, then greenhouse gas CO 2 changes after Feedback System… Cryosphere Now 16 October 2008 Read for Mon: 351-363
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Honors 1360 Planet Earth Last time: The Cryosphere:
16 October 2008. Honors 1360 Planet Earth Last time: The Cryosphere: Hyp : Milankovitch Cycles : Summer insolation at high northern latitudes controls glacial/interglacial cycles! Pred : Should see strong correlation between hi-N-lat summer - PowerPoint PPT Presentation
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Honors 1360 Planet EarthLast time:The Cryosphere:Hyp: Milankovitch Cycles: Summer insolation at high northern latitudes controls glacial/interglacial cycles! Pred: Should see strong correlation between hi-N-lat summer insolation and global temperatureObs: Nope. But transitions occur when insolation is changing in the right direction, and power in 18O at orbital periods indicates they are related!Hyp: So there must be something else going on too…Obs: CO2 and palaeotemperature proxy 18O strongly correlateObs: Temperature changes first, then greenhouse gas CO2
changes afterHyp: A Feedback System…
Today: Cryosphere Now
16 October 2008
Read for Mon: 351-363
Hansen et al. PNAS 2006concludes “Global mean temperature in 2005 was the warmest in 120,000years”…
Mann et al.,Eos 2003concludes four different palaeo-temperature proxies are in general agreement (but with large uncertainties)
EarthClimateSystem
Solar Energy
Ice Albedo (+)
Bio-CO2 (+)
Bio-SO2 (+)
Because of feedbacks, small changes in input (solar) lead tolarge changes in the system state:
In chaos/system theory, like Lorenz’ butterfly effect…
Earth climate history for the past 2 Myrs suggests two stable points (glacial, interglacial) with unstable transitions
Some Perspective:Minimum sea level in Pleistocene~ 100-120 m below present
Maximum sea level in Eocene (50 Mya)~ 100-140 m above present
Temperatures during early Eocene~ 7 degrees above present