Why are the sierra nevada lakes very sensitive to changing climate?

Because the surrounding mountains contain very little soil, and nutrients are easily washed into the lakes, which could cause algae blooms and other problems. But It is not climate change, they are sensitive to different weather patterns.

Humid continental climate is found in the interior of continents between the 30 and 60 degrees latitude, but usually above the 40 degree line.   40 degrees north of the equator means less direct sunlight and therefore less warmth.   this climate is mainly found in the northern hemisphere since there are no major landmasses in the southern hemisphere.  if you live in northern indiana, you know all about humid continental because that is the climate type you have!