While doing some research for my upcoming book, I was rummaging through early papers on sea level data at the CU Sea Level Library. I found there the 1982 paper Global Sea Level Trend in the Past Century by Gornitz, Lebedeff and Hansen, all of NASA’s GISS. I enjoyed a brief mention of past global temperature it contained and thought you might enjoy it and another statement, too.
While presenting the typical alarmist conjecture about the possible collapse of the West Antarctic ice sheet, they made a statement that is atypical of alarmists:
A key application of the sea level trend concerns the potential destruction of the marine West Antarctic ice sheet (1). It can be argued that the ice sheet is not close to disintegration, because it survived the Altithermal ( ~ 5000 years ago) when the global mean temperature was perhaps 1 deg C warmer than today.
“Altithermal” is another term for the Holocene Climate Optimum.
Global surface temperature data produced by GISS indicate global surfaces have warmed since 1982, and, of course, the weasel-word “perhaps” means it may have been warmer or cooler during the Holocene Climate Optimum than the claimed 1 deg C. But I found it amusing that Hansen and others were noting in 1982 that global surface temperatures may have been warmer in the past…without the assistance of human emissions of CO2.
After the presented quote, Gornitz, Lebedeff and Hansen then go on to explain how the collapse of the West Antarctic ice sheet is still possible, but they hedged their bets with a plethora of weasel-words…and the following statement:
We should emphasize that we have no evidence for such a process.
Not much has changed over the past 30+ years from the alarmist wing of climate science: lots of weasel-words and lots of imaginative speculations, which are not even supported by their climate models…models of a planet that bear no relationship to Earth.
Bob Tisdale - Climate Observations 
When I confirmed the Standard Atmosphere (SA)–and the physics behind it, as the predominant thermodynamic process in the atmosphere–one of the telling points that soon became obvious is that the surface temperature of 15°C in the SA (known for over a century) was larger than the present widely-claimed global mean temperature of 14.7°C, despite a century of supposed warming. (Of course, in the 4 and 1/2 years since then, the alarmists have put out claims as high as 15.7°C, to muddy the waters. The whole business of always talking in terms of “temperature anomalies” instead of temperatures has enabled them to get away with that. And my confirmation of the SA tells me the global mean temperature is 15°C, not 15.7…of course, everyone uses 15°C on a daily basis, not caring enough to even wonder that that number is over a century old, despite all the “global warming”. This is, in my professional view, a good reason to be a denier–not just a “skeptic”–of the entire “global warming” narrative.)
Thanks, Bob. A good find.