The 100 Kyr cycle. Agnes Barszcz. Who wants to be a climatologist?. 2 teams: The Aphelions The Perihelions Rules Joker. What I am going to talk about. Various hypotheses for 100 kyr cycle Why Milankovich is wrong Suggest a new hypothesis See if it is reasonable
-> Top five reasons that we should NOT……
Spectrum of 100-kyr glacial cycle: Orbital inclination,not eccentricity. By RICHARD A. MULLER* AND GORDON J. MACDONALD
http://www.pnas.org/cgi/reprint/94/16/8329.pdf , 1995
The crux of the problem
Ocean is ice free
->->Land ice sheet grows
->->-> At year 90 kyr, the global SST reaches zero degrees
->->-> Sea ice switch is ON
->->-> No more sea ice growth
How do we get out of an ice age??
->->-> Less moisture present in polar regions
->->-> The glaciers retract
-> How does that affect the land ice sheet?
-> What is causing it to melt anyways?
->What will cause the abrupt acceleration of the melt down of sea ice?
->We are back at the starting point!
Ok so we have a scheme…
Does it practically?
What changes the strength of the THC?
V= V max –V min
=2.4 e16 m3
maximum = 0.09 e6 m3/s
minumum = 0.03 e6 m3/s
-> Cycle is longer by 10 kyr
-> Less saw-tooth like shape
What will happen??
-> Shorter growth/Longer meltdown
->Shorter but more symmetric cycle
-> Permanent sea ice cover
->No land Ice
-> Makes the sea-ice mechanism less effective as a switch
->Reduces the amplitude of the oscillation and shortens the time scale
How will the emissivity evolve between a glacial minimum and maximum?
-> Why longer?