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I was reading a report on Global Warming where IPCC has claimed that the temp rise in past 100 odd years has been of the order of "0.72 Deg C +/- 0.18 Deg C with a confidence interval of 90%".

I wish to know if there were such precise temperature measurement techniques available 100-150 yrs ago and whether so many metrological stations were there all around the globe with such precise temp instrumentation to arrive at such a precise data.

Regards
Grishma

We are automation experts here, not meteorologists or climatologists. You are probably better off researching answers to those questions somewhere where there are people who know those answers. However, I will try to answer as best I can.

I can't give you any precise numbers as to what accuracy was available in temperature measurements of 100 years ago (e.g. 1907). I think you will find though that when it comes to taking accurate air and water temperature measurements, the technology of of "100 odd years" ago was not really that much less capable than that of today. The greatest advances since then have been in being able to collect it more economically, and perhaps more importantly, transmitting and analysing it more quickly.

As to how widespread the measurement sites were, I know that Britain had meteorological stations around the world during that time period located in various colonies, naval bases, and coaling stations in every corner of the globe. Naval vessels and survey ships also took readings as they crossed oceans and visited foreign ports. Accurate temperature measurements were considered very important to creating navigation charts, which in turn were considered vital for safe and reliable sail and steam navigation (which was in turn the key to being a world power). No doubt France and several other countries had similar capabilities, if perhaps not on quite as extensive a scale.

In other words, don't sell short the capabilities people had in those days. If you would like a real eye opener, read some electrical engineering books from the 1930s, and see what people were doing in industrial controls in those days without transistors and computers. It might surprise you.

I am sorry. It was not my intention to be critical or biased of capabilities of people of yesteryear. I apologize for not putting my question properly.

Grishma