Is there a non-warming explanation for any of the tangible evidence of the MWP?

Question

How did Lake Naivasha in Kenya dry up? How did it stay dry for 200 years? Why did it recover - and why hasn't it dried up again despite higher water usage, if it's hotter now than it was in the 1100s? Why were the droughts so bad in the American Southwest that it devastated the Anasazi civilization? How did they maintain dairy farms on Greenland? How did England - hundreds of years before mankind had developed cold-hardy varieties of grapes - become wine country - and then cease to be wine country? Why were tree lines higher in the Sierra Nevadas? Why are retreating glaciers in the Alps revealing archaeological finds from prior warm periods?

Answer 1

Obviously, these were all "local" events, while tree rings and other proxy measurements are always representative of the entire globe.

However, finding human evidence in melting glaciers is pretty compelling evidence that:

a. It was warmer than now in the recent past.

b. Earth and life survived this warming nicely thank you

The Alps are not near any ocean, and high enough to be representative of global climate.

  

Answer 2

The MWP was basically a series of localized warmings.  North America, Europe, and Africa warmed at different times.

Answer 3

The real answer is people are just guessing about global temperatures in the past. But their guesses are not completely baseless.

You'd probably be safe to state that it was warmer 800-1300 a.d. (approximate) in Europe and North America than now in Europe and NA.

In Antarctic, there is some ice core evidence that there was a cold period between 1000-1100 a.d. For what it's worth.

Corals in the South Pacific suggest a cool, dry period during that time frame.

Japan lake Nakasuna suggest that Japan also had the MWP and little ice age, like NA and Europe.

But to take a global temperature from such little data is problematic. Either way. In fact, it may be problematic to try to estimate a global temperature today.