[bdw5204]

It's also worth noting that reliable daily temperature records only go back to the late 1800s. The way you know this is that there are no record highs or lows in 1788 or even 1828. Most likely, at least some of the real records were set prior to the invention of temperature measurement.

On a related note, global population data before about 1800 or so is also unreliable because censuses hadn't been invented yet. During the Enlightenment, people actually debated if world population was increasing or decreasing. Many thought it had been constantly decreasing since the decline and fall of Rome. In general, reliable statistics for more or less anything are newer than the United States of America.

[graemep]

Even after that records are not really up to current standards (and I am sure even current standards are not perfect - things will always go wrong). What would have been the highest temperature recorded in the UK in the 20th century not counted in records because there were issues with its reliability:

https://en.wikipedia.org/wiki/1911_United_Kingdom_heat_wave#...

[potato3732842]

>It's also worth noting that reliable daily temperature records only go back to the late 1800s. The way you know this is that there are no record highs or lows in 1788 or even 1828. Most likely, at least some of the real records were set prior to the invention of temperature measurement.

There's a whole meta-genre of academic papers that consist of taking unreliably measurement logs from prior centuries, comparing them to what the current best scientific understanding of the field is and then saying "aha, X wasn't mistaken about observing/measuring/concluding Y in conditions/location Z, his instrumentation was likely out of tune by a factor of N, if we re-do his math with the following error bars and plot the results you can see that what he reported is within the limits of our understanding of the subject today".

I'm not gonna say it's useful or useless science, but it sure is interesting to find out how close to modern understanding some of those guys back then were within their niches if you account for the quality of their equipment despite sometimes very unscientific conditions.

[Hilift]

> The way you know this is that there are no record highs or lows in 1788 or even 1828.

This is not specific to weather, although one interesting example would be California in November 1861 - January 1862. Most people think of the gold rush, but there was also a 20 year drought that ended with the largest flood in recorded history. 10 feet of precipitation in California, in the form of rain and snow, over a period of 43 days. It was followed by a huge bloom in vegetation, and the rancho cattle population quadrupled. Then another drought in 1864, that wiped out most of the cattle. And a smallpox epidemic that wiped out 90% of the remaining native population.

https://en.wikipedia.org/wiki/Great_Flood_of_1862

https://www.latimes.com/archives/la-xpm-1991-06-13-nc-780-st...

[vidarh]

Uhm, censuses are described in the Bible - in fact one has a central enough role that even a committed heathen like me is aware of it -, and existed many places on a similar timeline. I have no problem believing that they were imprecise, and not widespread enough to give good global numbers, but they had certainly been invented much earlier.

[Cthulhu_]

There's also the Domesday Book (https://en.wikipedia.org/wiki/Domesday_Book), which wasn't an exact census but it did log 268,984 people considered to be the head of a household; based on this and all the ifs and buts around the number, they estimated the population of Wales and England in 1086 between 1.2 and 1.6 million people.

But it was more a taxation thing.

[User23]

Given that we basically use the same technique for censuses today, the ancient ones probably weren’t especially less reliable.

[graemep]

Yes, but they were imprecise and inconsistent.

The Roman Empire had a motive to take a census (for things such as taxation of its subjects) and the means to enforce it over a wide area, neither of which survived its fall.