I’ll follow up on the bad news about glaciers next week. In the mean time, here is an article on the drought in California that I originally published on the old blog site–since the drought is ongoing and has already spawned some awful wildfires, it seemed timely to revisit the issue. This article was originally published in February, 2014 and has since been edited for greater clarity.
For much of the United States, this winter has been all about cold and snow. But for the other half of the country, though, this winter has been about drought and heat. And it turns out, the two extremes are related.
California is entering its third consecutive year of deep drought. In 2013, California as a whole got less than a third of its average amount of precipitation. January is typically one of the area’s two wettest months, but as of mid-January, some areas had received only a trace of rain. Los Angeles had received no rain at all. This is the driest period on record for California. Tree ring studies suggest that this is the driest the region has been for nearly 500 years. Nevada and Oregon are also in very serious droughts, and parts of eight other states are also in a state of Federal emergency due to drought.
Much of the Western U.S. is also unusually warm. Parts of California topped 80 degrees in January, while parts of Alaska approached 60 degrees. 60 degrees in Alaska in January is not only bizarre but also dangerous, since the warmth has caused a massive avalanche that completely cut off the only road into the town of Valdez. Wherever it occurs, heat makes drought worse by increasing rates of evaporation.
At the beginning of February, the California Water Project, for the first time ever, announced it would not supply any more water until further notice. The move means that the state must now rely only on local water sources, such as wells, without access to regional reserves.
The current drought will probably break eventually, but this sort of thing could be the new normal. Current land and water use policy in the American West is based on the amount of water available in past years, but we now know that the recent past was an unusually wet period for the region. What looks like drought to us may simply be a return to normal. Over the past thousand years or so, this area has also experienced several “mega-droughts,” extra-dry periods lasting a hundred years or more.
If California is heading into a mega-drought, or even just returning to the historical normal, then there won’t be enough water for its people and industries, a shortage that will have national consequences. More wildfires means that California will have to draw on out of state resources more often, potentially depleting the country’s ability to fight fires in other regions. 15% of the food sold in the U.S. in grown in California, the loss of effective irrigation would raise food prices nation-wide.
Does this have anything to do with global warming? In a word, yes.
This winter’s wet cold in the east and the dry warmth in the west are related. A persistent blocking high—a huge bubble of high pressure—has sat over top of the northeast Pacific for months. As the name implies, the blocking high prevents storms carrying moisture from the Pacific from making it to shore. The bubble also diverts the jet stream northward, directing warm, tropical air straight up into the arctic and destabilizing the polar vortex. We’ve gotten used to “polar vortex” being used to mean a cold snap, but actually it refers to a ring of high wind around the poles that usually serves to keep the coldest polar air in place. When the polar vortex weakens, it leaks, spilling frigid air into unusual places, like Atlanta, Georgia. This blocking high has been in place for nearly a year now.
But this process—a weakening of the polar vortex because of melting sea ice—was predicted by climate scientists years ago. It’s exactly what they said would happen. So, yeah, this is what climate change looks like.
So, let’s DO something about it, please?