I don’t know why you bother. He’s the king of this on this board: https://en.m.wikipedia.org/wiki/Sealioning
These discussions often get fractious, with people attributing claims and positions to others that aren't reflected in the posts. For those that are genuinely interested in the topic, and in understanding possible solutions (<<see, that's not a denial of climate change, nor of the human contribution) a reasonable starting point is to look at the IPCC Reports, but don't take them at face value, investigate the studies that are linked in the reports, and see what those scientists and their studies actually say before it gets distilled down in the various stages to produce the reports. Oh, and don't be selective and simply hunt for a graph that suits your personal position, or you think proves someone else wrong. Do it with an open mind. You could even look for scientific studies that didn't get included in the report.
I spent yesterday standing in a big unairconditioned tent wearing a suit at Farnborough International Airshow. I'm looking forwards to spending today standing outside on the balcony of a chalet in a suit watching the air display with customers. I didn't think I'd ever miss the year it pissed down continuously....
They're generally based on data from 1880 onward as there wasn't accurate worldwide temperature data before then.
There's a debate to be had on the locations of the weather stations, technology used and changes due to urban sprawl post mid 1800's, but to claim that there wasn't 'accurate' data before then would make the scientists blood boil. These measurements are a fundamental basis of the hockey stick graph, and other investigations by credible scientists that reached other conclusions. Again, there's a debate to be had on whose conclusions are correct, but they all rely on pre-1850's data, and are an oft quoted driver for current measures.
Someone saying in a discussion on TV that in 2019 800 people died from heat related causes whilst over 60,000 died from the cold.
I'm not sure what point you're making. The changes in the climate will occur at both ends of the spectrum, and the range between the extremities will get wider and more pronounced, even in the same year.
That'll be the NASA that comments on pre 1850 temperatures on their site, and use that data in their work.