Sorry, I don't work at NASA nor am I a scientist in this field, but it should be obvious there's more to their data and analysis than just what's found on that

Sorry, I don't work at NASA nor am I a scientist in this field, but it should be obvious there's more to their data and analysis than just what's found on that URL. If you can click around their page and site, you can find a layperson FAQ where they give a broad explanation of their methodology (if you don't want to click through to the cited research papers). Here's the FAQ question relevant to why the 1951-1980 period is chosen: https://data.giss.nasa.gov/gistemp/faq/index.html#q102 https://data.giss.nasa.gov/gistemp/faq/index.html#q102 > Q. Why does GISS stay with the 1951-1980 base period? > A. The primary focus of the GISS analysis are long-term temperature changes over many decades and centuries, and a fixed base period yields anomalies that are consistent over time.