No, we have data that goes back millions even 100's of millions of years. The granularity of much of that is rather coarse. The data for 1000s of years is qui

No, we have data that goes back millions even 100's of millions of years. The granularity of much of that is rather coarse. The data for 1000s of years is quite fine grained. There are trees that are over 1000 years old and ice cores that give near monthly data going back a very long time. There are also a lot of other clues as to climate from other sources. The UK's Met. office was established in 1854 and I'm sure that several others are just as old. That's simply when weather prediction became interesting. There is loads of data (temperature, wind speed etc) from before then, from ships and land based sources. We even have data from ancient civilisations and this can sometimes be corroborated and hence other things be reasonably inferred. More modern, we know that people were ice skating on the river Thames in the 18th century - that's quite a big river and it does not freeze these days - that was a mini ice age. Anyway, we have a lot of data and it goes back a long, long, way (with a few gaps)