Sierra Nevada Snowpack Lowest In 500 Years

The Nature Climate Change note starts like this:

To the Editor — California is currently experiencing a record-setting drought that began in 2012 and recently culminated in the first state-wide water restriction. The snowpack conditions in the Sierra Nevada present an ominous sign of the severity of this drought: the 1 April 2015 snow water equivalent (SWE) was at only 5% of its historical average. In the Mediterranean climate of California, with 80% of the precipitation occurring in the winter months, Sierra Nevada snowpack plays a critical role in replenishing the state's reservoirs and provides 30% of its water supply. As a result, a multi-year and severe snowpack decline can acutely impact human and natural systems, including urban and agricultural water supplies, hydroelectric power and wildfire risk.

The lowest in 500 years. Source

I talked about climate risk the other day, noting that Flatland humans do not (and can not) assess it properly. On that subject, here is Jerry Brown talking about California and future migrations (short, 50 seconds).

"And what we see in Europe now, mass migrations, that will happen in California. As Central America and Mexico warm, people are going to get on the move [to California]."

When we see that the Sierra Nevada snowpack, which provides about 30% of California's water, is at a 500-year low, we are entitled to ask what the risk is to the Golden State.

Suppose this drought continues more or less uninterrupted for another 5 or 10 years. That would not be unusual by historical standards. The biggest difference between the current situation and that in past "megadroughts" is that there are now 38,800,000 people living in California.

So when Governor Jerry Brown talks about mass migrations, it seems to me that he might consider the risk of a mass migration out of California to other states if this drought continues at the current severity level until 2020 or beyond. The odds of that happening, at least in the foreseeable future, seem to me to be a lot higher than the odds that California must be prepared to receive millions of Central Americans driven north by climate change. And why would Mexicans and others in Central America migrate to a place where there's no water?

But that bleak scenario doesn't seem to have occurred to Governor Brown. As always with humans, the "thinking" is

It Can't Happen Here! It Can't Happen to Me!

Again I remind you that saying that there is a risk of something bad happening and predicting that it will occur are two different things. Even if this grim scenario does not come to pass, there is in 2015 a significant (non-trivial) risk that it could to come pass. It's a worst case scenario, for sure, but sometimes shit happens.