See, friends, this is how science works: you observe,you hypothesize, you experiment, you observe, you draw conclusions. As new data is uncovered, you adjust your conclusions based on the data, not the other way around.
From the Daily Mail:
Global warming: Earth heated up in medieval times without human C02 emission.
‘We showed that the Northern European climate events influenced climate conditions in Antarctica,’ Lu says. ‘More importantly, we are extremely happy to figure out how to get a climate signal out of this peculiar mineral. A new proxy is always welcome when studying past climate changes.’ (my emphasis)
I repeat my assertions: if you don't know the correct temperature of the Earth, you can't get me upset over fluctuations in temperature; you cannot prove humans have anything to do with the fluctuations in global temperature.