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447 points Brajeshwar | 1 comments | 03 Sep 23 14:53 UTC | HN request time: 0.217s | source
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oceanplexian ◴[03 Sep 23 17:04 UTC] No.37371997[source]▶
If you pull up the last 2,000 years in the Yearly Average Observed Temperature anomaly, from 536 - 537 there should be a global average temperature anomaly of -2C to -5C from the Volcanic Winter of 536 (A period of 18 months where the sun was dimmed by volcanic ash), but the graph shows <1C. There's tree ring evidence of it from all over the world.

If they missed this, this puts into question all the rest of the data IMO.

replies(5): >>37372030 #>>37372046 #>>37372068 #>>37372111 #>>37372662 #
1. chrisfosterelli ◴[03 Sep 23 17:10 UTC] No.37372046[source]▶
> For the years leading up to 1850 we use PAGES2k Consortium reconstruction data. It is based on models where temperatures are reconstructed from proxies. Proxy analysis has higher uncertainty, and we display the smoothed set to highlight the longer-term fluctuations.

It would be in there, but smoothed over instead of the year-by-year entries that you are looking for.

For a lot of datasets like this that are before modern monitoring programs, you can often tell when something "big" happened in a certain time period or year from another source, but then you have to decide how to incorporate that with your long-range data that doesn't have year-by-year values. Sometimes it's best to just choose one method that covers all of the years and stick with it instead of modifying your model based on what you "think" is right from other sources.