So far 2016 is the warmest year on record. Following 2015 which was previously the warmest year on record. Out there in Death Valley they're flirting with surpassing the world's record temperature (134ºF from 1913). But it wasn't that long ago that we were still getting glaciers forming in the Sierras.
During the Little Ice Age, which lasted from the 1300's to the middle or end of the 1800's, the glaciers in the Sierra Nevada expanded and contracted with the temperatures. But those cooler temperatures are gone for the foreseeable future. Will next year be another record breaker? Maybe not, even with a higher mean temperature, regression towards the mean might mean it won't be as hot as this year. But one thing is sure, it won't be as cool as it used to be.
When I moved to Tehachapi fifteen years ago I lived in an apartment with no air conditioning. There were generally only a couple weeks a year where the temperatures were high enough that I wished I had one. And that was only because the temperatures at night were still high. I could sleep comfortably under a window fan. But now these last few years I'm using my air conditioner more and more each summer. And the heater doesn't seem to work quite as hard in the winter.
Just as the ecosystem changed after the last Ice Age, things are going to be changing in the landscape around us. As landscapes try to recover after a fire (for example), I wouldn't expect to see the same plants come back. Perhaps since Joshua Trees need cool temperatures they'll be moving up the mountains to reach temperatures cool enough for them. And the Mojave Desert will fill up with plants from the southern deserts.
It will take time. The climate is changing and the plants and animals around here will change too. The landscape will adapt to the new reality. But me, I'll adapt too. I'll use my air conditioner even more (hopefully I'll be able to afford it) and buy a toaster oven so I can still do a little baking during the summer. Of course there are still a couple months left where we can expect summer temperatures. Maybe I should start pricing those toaster ovens now.