In truly fascinating new reasearch, scientists have searched historical records to collect data about when the grape harvest began each year. Their research wasn’t published in the Journal of French Wine (I don’t know if there even is one), it was published in the journal Climate of the Past. That’s because the date when the grape harvest begins is a clue to temperature.
The importance of clues like this is that they extend farther back in time than thermometer records. The grape harvest dates (GHD) start in the year 1354 — centuries before the thermometer was even invented. Also quite important: they are all for the same location: Beaune, France.
When the temperature is hotter, the grapes are ready to harvest earlier. When it’s colder, they harvest later. If climate is really heating up, the grape harvest should be getting earlier. And what did they find? This: