|Another view of the drought in the Santa Cruz mountains, above Silicon Valley|
Good news: You're all on the right track!
This Challenge, like last week's a some others we've done, is very "key term" sensitive. That is, you have to figure out what the right words are to use in searching.
As you've seen, queries like
[ 2000 years rainfall data California ]
are too general. The search results are fine, but not specific enough for what we seek.
In cases like this, you have to know / learn / discover the terms that are more closely allied with your task.
You've already got a couple of them:
And you already have some clues that there were long-lasting droughts in California's past. This suggests that searching with terms like "severe drought" or "persistent drought" might be useful.
As always, this has been a great discussion. I'm looking forward to the rest of the comments today!
It might also be worth considering "what would the perfect kind of result be for this question?" Are you looking for a scholarly paper, a data table, a chart? How would that affect your search strategy?