There was a time when the weather was fairly predictable; it snowed and rained in the winter, got green and balmy in the spring, hot in the
summer, and cool and colorful in fall. I've seen this change in my lifetime of living in northern California and Nevada, on both sides of the
Sierra. It's hotter, colder, drier, and the severe weather seems more severe. Basically, the predictability to which I had grown accustomed
has gone away.

I think some of this is attributable to human activity, but I also believe just how much of it is so attributable is a question with no definitive
answer. Various research has demonstrated numerous climate shifts over the last few million years, long before humans could have had
anything to do with it. In the last few thousand years of recorded history, there have been some fairly dramatic climate events, still before
people began spewing fossil fuel pollutants into the air. Northern Nevada was covered by a huge inland lake somewhere around 12,000
years ago; Pyramid Lake just north of Reno is a remnant. There are also celestial conditions having nothing to do with humans, such as
the wobble of the Earth on its rotational axis. Egyptian astronomers during the time of the pharohs had this one figured out.

Realistically, most people aren't going to dramatically change their habits instantly. But if all of us do a little here and there, get
comfortable with some changes, then do a little more, the cumulative effects will start making a difference. Change a couple of light bulbs
to compact flourescents, plan car trips better so as to do less driving, replace some lawn with something needing little or no water, stuff
like that. I've done the light bulb thing, try to take care of several errands at once when I get in the car, and have some lawn that's about to
turn into nice pavers.