How do we REALLY know? (Score 1)

How on earth do we know what the tempetures were 400 years ago? Records weren't even started until about 80-100 years ago, the rest is pure speculation. Even the early records aren't going to be very accurate, as measuring devices weren't super accurate. And according to them, we have wamred 1 degree over 400 years, which the allowance in variation for themometers is usuall 2-10 degrees. I mean you read 10 themometers you will get 10 different readings, nothing is accurate to within one degree. Really, we are doing a lot, but bottom line is the human race is growing and will produce more emissions as a result, this is not a bad thing, we will just have to adapt to changes as they come and they will come, but not for quite some time.