Having experienced the hysteria that was the Global Cooling scare of the 70s and early 80s (where the Secretary General of the UN even made so bold as to declare we had been irrevocably committed to sustained cooling), I have to be at the very least cynical that Global Warming was to begin only a decade or two afterwards.
I am by no means a Global Warming denier, but I am a skeptic of all things doom and gloom.
1) I recall the prediction that we would have exhausted the worldwide supply of tungsten by the late 1990s.
2) I recall be schooled that we would exhaust our fossil fuels by the year 2010.
3) I recall reading an old history text that warned that the world was running dangerously short of coal back in the 1880s...
4) And how many distopian predictions were there during the height of the Cold War that mankind would be long gone prior to the advent of the year 2000?
5) And might we have forgotten the Y2K computer bug that was set to erase all technological progress?
This is not to say that care is not warranted and excesses should not be curbed, but rather it is an observation that the medias love nothing more than a hysterical public, and will typically do whatever it requires to keep them agitated...their cash-flow depends upon it.
This is why there are few in-depth investigations into the unlikelihood (or even relative lack of importance) of any of the above examples coming to pass while the hysteria is in full gear. It is also why the positive balance to such negativity is rarely offered.
To give some fair examples of solutions and/or assuagements from your concern of global warming:
1) To contend with California's impending drought, it need look no further than the existing technology of desalinization. Yes, water will cost more, but likely it is currently undervalued anyway so it will encourage conservation. Further, with increased familiarity with the systems it is not unreasonable to assume prices will descend with time.
2) If GW actually happens:
a) There should be a great deal more arable land opened up in countries whose grounds are currently permafrost.
b) CO2 levels in the atmosphere are currently at their lowest levels in hundreds of millions of years...increasing that CO2 will increase the rate of plant growth according to experiments conducted at greenhouses worldwide (as an aquaculturist I frequently must contrive to raise CO2 in my habitats in order to spark lush plant growth). Increased growth will serve to trap higher levels of carbon in the fibers, roots, and trunks of plants, removing it from the atmosphere...as it has been doing for hundreds of millions of years...
c) Increasing temperature increases habitat diversity and range.
d) Increased temperature allows for a greater level of humidity...which may naturally lead to greater cloud cover, which may lead to less skin cancer.
Further, greater cloud cover would potentially reject more solar energy due to the higher refractive index of water crystals in the high atmosphere and the lighter color of clouds relative to that of the ground...
e) A higher global temperature should reduce heating costs and the combustion of fossil fuels...
f) Historically, periods of warmth have been strongly linked to periods of decreased global hostilities due to the increase in crop yields.
g) As the percentage of Oxygen in the atmosphere is displaced by CO2 it is expected that forest fires should be fewer, smaller, and more frequently doused by increased rainfall.
Certainly many of these items could be debated (something for which I have no inclination as they are merely presented to demonstrate that one-sided discussions often limit their scope to the worst-case scenarios to the exclusion of the rest of reality), but the point at hand is that far from being the worst news imaginable, Global Warming at worst likely offers the world new opportunities to try different things...and, in my humble opinion, is certainly far better than the previous worry: the threat of a new ice age, now overdue, that would shrink arable land and humanity's ability to survive to only a few hospitable zones...so cheer up!