I'm not questioning the data per se, as you can tell from looking at 2000 up to today that the median is rising.
I'm just a bit surprised by the accuracy in the late 19th century. I expected less.
https://data.giss.nasa.gov/gistemp/graphs_v4/
it doesn't take a very large number of sensing stations to get a reasonable global mean, surprisingly. You get pretty much the same result as the serious efforts if you just pick ~300 random weather stations.
Granted their are two relevant kinds of systemic error. If temperatures where more likely to be 0.1 than 0.9 then rounding would introduce bias. But, as our temperature system is arbitrary that seems unlikely.
No, not even close. You were probably lucky to get one-degree accuracy, if that.
This is one of the first red flags that I noted when I started paying closer attention to climate-related stuff about 15 or 20 years ago. I did a little digging, and it turns out that there is a mathematical theorem (I forget the name of it) that allows you to do things like this (derive a higher level of accuracy than the data would otherwise allow) if you know for a fact that the associated errors pretty much all cancel out. But you have to know this, from prior sampling or whatever; you can't just assume it. But that's what these folks are doing - waving their hands and just assuming that the errors mostly cancel out.
To add insult to injury, for other portions of the data they state that they have the right to make routine, automated adjustments because of systematic errors in the data. But you can't have it both ways - assuming that the errors mostly cancel out on the one hand, while on the other hand claiming you have the right to make adjustments because, you know, those errors don't actually cancel each other out after all.
> I'm not questioning the data per se
You should be! Most of the "data" here is either of remarkably low quality, or just pretty much made up.
Some claim the world is not getting warmer.
Some agree it might be but we don't know for sure.
Some agree it is getting warmer, and say it might be due to human activity, but we don't know for sure.
Some agree it is getting warmer, but claim it is due to some other cause than human activity.
Some claim it is getting warmer, but increased co2 will bring huge benefits.
Some agree it is getting warmer and agree that increased co2 brings harm, but that efforts to reduce emissions would bring great economic harm.
Plus probably several other positions I have not mentions. Also, some people try to combine several positions.
You know, you all would be more persuasive if you could first reach agreement among yourselves. Or at least if the advocates of each position would be as critical of the other positions as they are of the mainstream position.
You're reducing multiple known sources of error to a single one for some reason, which doesn't help here. Here's an example: my car shows 4% higher speed than the real one due to difference in expected tire diameter. Additionally it has some small dynamic error of speed measurement. In this case I can "have it both ways". I can correct for the known difference and use multiple measurements to get a higher precision speed reading.
The same thing applies to old temperature measurements if you provide good explanation of the systematic error.
And to my point, no, you can't claim that the errors in various temperature readings mostly cancel each other out, without having any solid proof of that. Nor can you then turn around and claim that since there are enough errors out there that obviously don't cancel out, that this then gives you the right to set loose a computer program to blindly "correct" those errors, said program having been constructed using whatever models and biases you were operating under at the time. (Those "corrections" may not be anywhere close to accurate, in other words.) But that's exactly the kind of thing they've been doing.
But the problem is many other measurements confirm the surface temperature results. Air temps agree with ocean temps, various proxies agree with those (ice extent and mass for example, are declining as would be expected with a warming trend)
Now, does 1800s temperature data have large errors? Yes, and those are reflected in surface temperature reconstructions by large error bars.
You are not the first person to be convinced that climate data is bad, some very smart people have felt that, and got funded by the koch brothers to do it right, and they did an excellent job, but got the same answers NASA, NOAA, and other groups did:
https://www.nytimes.com/2012/07/30/opinion/the-conversion-of...
https://realclimatescience.com/wp-content/uploads/2018/03/20...
Older data has been adjusted to be cooler and newer data has been adjusted to be warmer.
You can debate why it's been adjusted all you want, but the fact that the adjustments are there and they are adjusted to make newer data appear hotter is indisputable.
Here's an animated gif comparing the exact same data from NASA 2001 vs 2016 https://i1.wp.com/realclimatescience.com/wp-content/uploads/...
1880 is adjusted to .2 lower and 2000 is adjusted to .2 higher, along with everything in between.
As well, the fraudulent activity would be going on with satellite based reconstruction, deep sea temperature measurements, ice extent and mass measurements, all being done by other groups in various ways.
If you really feel that this is what is going on, it is possible to do your own reconstruction from raw data. The raw data, unadjusted, is freely available. If you pick a time frame to look at, where you have a few hundred stations randomly distributed around the globe, that are not changing during that time period, then you don't have to do any adjustments to the data at all. I've done this before, pulling raw data into MySql and analyzing it. You get limited to smaller chunks of time, but I got the same trends all of the professional groups got in that time period. This was something I did years ago, to try to cut through all of the rhetoric that one can read on the internet.
Having read scientific journals myself on and off for several decades now, one of the things I've noticed is that once a paper gets published in a reputable peer-reviewed journal, then that opens the floodgates for other related papers to get published using related data and related methods. And that's true even if the original paper used highly questionable data and highly questionable methods, as so many do these days.
The reality of scientific publishing today is that scientists need something - anything - of theirs to get published in order to build and maintain their professional reputations. And journals need something - anything - to publish; usually something provocative, too, otherwise nobody would bother paying the high fees that they charge. So a lot of what they publish is just their version of clickbait.
Funny you should mention Japan: Back when I did my deep dive, one of the cities in Japan (Tokyo, I think it was) was being held up as a worst case example for warming. And if you looked at the raw temperature data, the warming there was kind of scary enough as it was, but in the adjusted data it was just horrific. And I thought to myself that one of two things was going on here: Either the level of warming that was being claimed to have occurred there didn't actually occur, or that it puts lie to the notion that humans and flora and fauna can't readily adapt to such warming. After all, it's not like Tokyo is an apocalyptic dead zone or anything, now is it?
As to the raw data itself, the last time I checked the raw HadCRUT3 data that I used in my deep dive was no longer available (I kept running into broken links and such), and this data had only been provided under duress in the first place. I didn't really strain any muscles trying to look for it again, though. Nor did I originally have much luck trying to find similar data for HadCRUT4 (again I didn't look too hard), but I have seen passing references to it being out there somewhere.
And by "raw" I mean the data as it originally came in from the various temperature stations, without being manipulated in any way except maybe to get it all in a common format for easy processing. But apparently what I call "raw" and what some other folks call "raw" can be quite different things.
And unlike your situation, when I looked at the HadCRUT3 data (at least the version that existed at the time; I know they made some changes to it afterwards) what I found there was appalling. So either massive fraud was going on at the time, or (more likely) they had just allowed their computer algorithms to run amok on it without really quality checking the final results.
As to stations "not changing during that time period", I forget the details but you should be aware that some folks (not me) have gone so far as to track down a few such stations (those which were well-documented and well-maintained, but with no documented moves or changes), only to find that the algorithms had made adjustments to them anyway! As for the local station that I used, the adjustments were such that it made it look like this station had shifted from condition A to condition B (that it had moved or whatever), then shifted back to condition A, then back to condition B, and so on, and that it shifted by exactly the same amount every time, too. Then rinse and repeat, every few years, which is hardly a realistic scenario.
BTW, all of those changes were warming changes, too. There was never a cooling change that I saw, at least not for my local station nor the handful of other stations that I also checked. The most that I saw was those periodic shifts back from the "adjusted" (warmer) data to the "raw" (cooler) data.
I did that deep dive about ten years ago, BTW, and the local data set I used went back to about 1870 or so - a solid 130+ years of data. I know a lot has changed in those ten years, but I don't know that much has really changed for the better concerning the data or the algorithms being used to process it.
As I believe I've already commented about in this thread, a few years back I did something of a "deep dive" on temperature data, paying particular attention to the temperature records in my own area. What I found there at the time was appalling, and even if I go check Berkeley right now what they show there appears to have little or no basis in reality.
Search my comment history for where I go on at some length about Berkeley (BEST) and the problems I see there. I suggest that you follow the links and go check out some things for yourself.
(Forgot to add) When I reviewed local temperature records myself, dating back to 1870 or so, I did indeed see a real but modest warming trend. But it was nothing like the warming which showed up after you got finished "adjusting" the data, which the climate folks routinely do.
As to deep ocean temps and such, lately those folks have been claiming to measure temperature changes on the order of 1/1000th of a degree per year, if not less. Now I don't know about you, but that just strikes me as BS on the face of it - more "statistical noise" than anything else. There are also claims made about ice melt and such, but if you do the math (the amount of ice claimed to have melted vs. the amount of ice still sitting there), you see that it falls within the same type of range - not even rounding error, just "noise".