Guys - thanks for enlightening me. My mental model had always been that temperatures HAVE been varying through time. Hence the mideaevel warm period and the mini ice age. As a geologist by background, my timeframe references are always a little longer than the average view so I didn't see the current warming as anything different from what has been "observed" in the last 1000 years. However, if the rate of current warming is different from what has been "observed" in the last 1000 years, then I guess the temperature proxie issue becomes important.

Thanks again.
Imran