It might have but there is nothing specifically we can point to.
Sea level was still very high by the PETM, although it is thought the inland sea in North America had already receded back. The north Atlantic just started opening at this time and there were very significant volcanoes when...
Continental Drift and sea-floor spreading does, in fact, affect global sea level. When new oceans are forming as a rift valley becomes flooded and then spreads out widening the new ocean basin, it actually forms at a very shallow depth - maybe 300 metres. Over the following 10 million years or...
The Albedo of the Earth (the amount of solar irradiance reflected) will increase with the glaciation event.
Take the small circle (60S) surrounding Antarctica in the graphic above and increase its Albedo from an average 0.41 to about 0.60. If you run all the numbers you would get -2C change...
CO2 (probably) did not fall until a few million years after the glaciation event which occurred between 33.6 million to 33.5 million years ago.
There is not a lot of CO2 estimates overlapping the period - the Zachos 2001 and Royer compilations show CO2 did not decline until between 32.2...
I've only spent a few weeks here and I certainly feel like I have gained a much greater understanding. I came here because the science was being discussed dispassionately and objectively (unlike "everywhere" else) and there were enough knowledgeable people around to correct any confusion. I...
Yes, there is some problems in the match-up. The old NasaTeam data has more of a dip at the minimum (compared to Jaxa's algorithm) than the rest of the year. I just left it the way it turned out but another adjustment could have been applied for that. 2009 should be the third lowest year...
I've spent a bit of time working with the sea ice extent numbers.
The satellite sea ice extent data actually goes back to 1972 but for whatever reason, it has not been matched up/reconcilled to the satellite data starting in 1979 provided by the newer post-1979 satellites.
I've matched up...
The EuroAsian glaciers waxed and wanned a great deal during the ice ages. Europe seems to be more succeptible to the Milankovitch cycles (with a 5,000 year lag) than the North American glaciers were. [The Milankovitch Cycles indicate that the ice ages should only last around 20,000 to 40,000...
I was going to post the CO2 note on that thread as well. One reason for all the large megafauna of the pleistocene to the end of the last ice age extinction event was all the extra grassland and savanna that was around.
Many of the megafauna were, in fact, mega-herbivores (grass herbivores...
One issue with the ice ages is that CO2 levels declined to levels (below 200 ppm for long periods) which gave a competitive advantage to C4 plants (mainly grasses) versus C3 plants (most other plants but includes some grasses as well). C4 grasses are able to grow just as efficiently with lower...
I think it is better to think of it as the Solar Irradiance reaching the Earth was 30% lower 4.55 billion years ago and it has increased in very close to a straight line over time.
So, Solar Irradiance 520 million years ago was = 1366 (0.7*520/4550) = 1319 = 252.8K
or -2.2K change 520...
The data I linked to sylas goes back 570 million years with the highest CO2 level being 7,069 ppm at 520 million years ago (GeoCarbIII from Berner). There are estimates going farther back with the last solid calculated ones being 12,000 ppm at the end of the last Snowball Earth period 635...
Most of the material I've accumulated comes from the NOAA paleoclimatology website. There is a lot of data there.
http://www.ncdc.noaa.gov/paleo/data.html
If you want to spend some time looking through subdirectories, the FTP site has lots of little surprises...
Thanks a bunch sylas.
I think I'm starting to see now.
I've gone through parts of Pierrehumbert's book before but it is a heavy read. I will come back when I've gone through it all this time.
Thanks for continuing to indulge me (because I do want to figure this out).
In your formulae above, can we just substitute the different Q's and T's between the surface and the tropopause emission level.
Surface Q = 390 W/m2
Surface T = 288K
Tropopause Emission Q = 240 W/m2
Tropopause...