New paper: Arctic amplification of temperature not primarily due to albedo changes, climate models need to be reworked

Santa Baby says: @ur momisugly February 3, 2014 at 7:56 pm
What I really have a problem grasping is that Earth’s global temperature for a very very long time up to 30 million years ago was stable at 23-24 deg C. And what was different was that there was less temperature difference over distance than there is today?
More ocean area and less land area?
>>>>>>>>>>>>>>>>>>>>>
(William McClenney could probably give you a better answer than I but I will take a stab at it.)
Possibly the Oligocene Epoch topography see: http://jan.ucc.nau.edu/~rcb7/globaltext2.html
map
There was the opening of Drake Passage.
Drake Passage and palaeoclimate

ABSTRACT: The effect of Drake Passage on the Earth’s climate is examined using an idealised coupled model. It is found that the opening of Drake Passage cools the high latitudes of the southern hemisphere by about 3°C and warms the high latitudes of the northern hemisphere by nearly the same amount. This study also attempts to determine whether the width and depth of the Drake Passage channel is likely to be an important factor in the thermal response. A deeper channel is shown to produce more southern cooling but the magnitude of the effect is not large. Channel geometry is relatively unimportant in the model because of a haline response that develops when the channel is first opened up.
Introduction
South America and Australia separated from Antarctica between 20 and 40 million years ago, isolating Antarctica and the South Pole behind a continuous band of ocean water. The palaeoceanographic record shows that this separation led to the accumulation of glacial ice on Antarctica and an abrupt cooling of the ocean’s deep water (Kennett, 1977). Both effects persist to this day. The palaeoceanographic record gives every indication that the isolation of Antarctica was a major step in climate evolution.
Today, the band of open water around Antarctica is most restricted between the tip of South America and the Palmer Peninsula, a feature known as Drake Passage. In one of the earliest scientific papers written about the output of an ocean general circulation model, Gill and Bryan (1971) showed how a gap such as Drake Passage alters the ocean’s meridional circulation and heat transport. With Drake Passage closed, the ocean transports heat southward by moving warm water poleward near the surface. Cooling at the Antarctic margin leads to deep-water formation and the northward flow of cold water at depth. With Drake Passage open, warm upper ocean water from the north is unable to flow into or across the channel because there is no net east–west pressure gradient to balance the effect of the Earth’s rotation. The ocean’s ability to transport heat southward is thereby diminished. Cox (1989), England (1992) and Mikolajewicz et al. (1993) carried out similar experiment…..

The closing of the Isthmus of Panama came quite a bit later:
The closure history of the Panama Isthmus
This may be of interest: Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania

…For the first time, we are able to place this event clearly in the plateau between the two main steps in the isotope records. This should enable improved correlation of the epoch boundary in a variety of geological settings, removing the need to shift the GSSP to some other section or point. The boundary corresponds to the climax of the marine extinctions and lies within an extended interval of severe global change that lasted ∼500 k.y., as bracketed by the first nannofossil extinction (Discoaster saipanensis) and the beginning of the early Oligocene glacial maximum
The Eocene-Oligocene transition marks a profound shift in global climate and marks the end to an extended period of predominantly “greenhouse” conditions on Earth that stretches back into the Mesozoic. The stepwise pattern of biotic events in the surface ocean and shelf seas, as recorded in the new cores, mirrors the pattern of global change. This pattern contrasts with sudden and catastrophic mass extinctions such as at the end-Cretaceous, suggesting that multiple causes, prolonged effects, and complex feedbacks between the geosphere and biosphere are necessary to explain the sequence of events that is only now becoming clear.

In other words they really do not know at this point. Unfortunately CAGW mania pollutes everything now a days so CO2 is the catch-all explanation that is tied to everything.