The likelihood of California experiencing more warm, dry years leading to severe drought is increasing, according to research by Stanford University scientists.
The study, which was published March 2 in the Proceedings of the National Academy of Sciences, found that rising temperatures combined with dry years are likely compounding severe drought more than dry, cool years.
The research team, led by Stanford Professor Noah Diffenbaugh of the School of Earth, Energy and Environmental Sciences, looked at California's weather data as far back as 120 years and the role of temperature and drought. The researchers found that the state's worst droughts historically occurred during the combination of warm and dry conditions.
"We've seen the effects of record heat on snow and soil moisture this year in California, and we know from this new research that climate change is increasing the probability of those warm and dry conditions occurring together," he told the Stanford Report last month.
In the past, California's temperatures came up dry and hot one quarter of the time, but in half of the past 20 decades, conditions have been warm and dry together, he noted.
Analyzing computer simulations of the state's precipitation and temperature levels throughout the 20th century with and without greenhouse gasses, human-created emissions were clearly implicated in the statewide warming and increased dry years. The probability of the two factors coinciding also increased significantly by the mid-21st century, according to their calculations.
"We found that essentially all years are likely to be warm -- or extremely warm -- in California by the middle of the 21st century," Daniel Swain, a graduate researcher and co-author, told Stanford Report.
The current four-year drought is also one of the longest periods in the historical record when the two conditions of dryness and heat collided, the researchers said.
Diffenbaugh noted the effects of such drought. He pointed to the unprecedented low snowpack this spring in an April 2 Q&A in the Stanford Report.
"This is the kind of extreme event that falls outside our historical experience. This is not only a low April 1 snowpack, but it is much lower than the previous record low," he said.
The record high temperatures currently being experienced this winter and spring combined with previous years of drought and the low snowpack mean the drought is likely to worsen this summer, Diffenbaugh noted.
Related content:
• Gov. Jerry Brown orders mandatory reduction in water usage
Comments
Los Altos Hills
on Apr 8, 2015 at 11:25 am
on Apr 8, 2015 at 11:25 am
In today's Mercury Newspaper there was a list of cities and their water usage. But no mention of Los Altos Hills usage within the Purissima Hills water district. In the past the amount of water usage has been huge. I think comparable to the Woodside usage. they need to cut back. someone needs to notice.
Another Palo Alto neighborhood
on Apr 8, 2015 at 12:20 pm
on Apr 8, 2015 at 12:20 pm
All of the media reports of this particular Stanford study seem to use the language "warm and dry", but don't provide any context to this terminology. Terms like "warm" can only have any meaning when compared to a baseline. So, what temperatures, and precipitations, are to be considered as "warm", or "warmner" during years that are considered as "drought".
Can it be that hard for “scientists” to produce studies/reports that actually clarify the issues, rather than muddle the waters with terms like “warm”, or “warmer”. Temperature range from lows (generally at night) to highs (generally in the afternoons). So, exactly how are these “warmer” temperatures determined? Yes, the historic data has been used, but what exactly does this term “warm” mean in the context of this data? If the baseline temperature is, say, 70 degrees for some period of time, and then the temperature for some period of time is 70.1 degrees—then “warm” means an increase of .1 degrees for some period of time. In this example, “warm” is a numerical difference, but it is hard to expect much difference in the daily temperatures that were recorded during the “warm” periods.
Moreover, there are over 150 definitions of the term "drought"--
Web Link
The term 'drought' has over 150 published definitions based on differences in regions, needs, and approaches. For the purposes of climate, we use the following definitions of drought:
o Meteorological: Based on the dryness (when compared to a normal or average amount) and the duration of the dry period. Region specific because climate can vary depending on geographic location, topography, etc.
o Hydrological: Associated with the effects of periods of below normal precipitation (snow and rainfall) on surface and ground water supples. Can be seen in low levels of in lakes and reservoirs, stream flow, and ground water wells. Takes longer periods of drought for these impacts to manifest, and extended periods of above normal precipitation to recover, depending on the severity of this type of drought.
o Agricultural: Links the characteristics of meteorological and hydrological drought to agricultural impacts. Focuses on precipitation and water supply shortages and how drought affects soil water deficits and evapotranspiration, as well as how susceptible crops are to drought during different stages of crop development, from planting to harvest.
o Socioeconomic: Associated with the supply and demand of some economic good (water, food, hydroelectric power) with elements of meteorological, hydrological, and agricultural drought. Occurs when the demand for an economic good far exceeds supply as a result of a weather-related shortfall in water supply.
It’s really hard to see much value in this particular study.
Palo Verde
on Apr 8, 2015 at 1:32 pm
on Apr 8, 2015 at 1:32 pm
Here are two excellent articles on California water use.
The first Web Link shows various usage by city and areas on maps.
The second Web Link has some fascinating photos of "green in the desert."
Downtown North
on Apr 8, 2015 at 1:36 pm
on Apr 8, 2015 at 1:36 pm
Anyone who treats lightly the question of drought and its potential long-term implications should weigh carefully some deep-time evidence.
Consider the bristlecone pines of California's White Mountains: the oldest were saplings in 2,500 BCE when the Egyptians were erecting the Great Pyramids. Core samples of 40 centuries of rings --- a few scarcely more than one cell wide --- extracted from these ancients reveal evidence of several droughts that lasted five-to-ten years, and one that lasted 40!
Last year National Geographic posted a story by Lisa M. Krieger that summarized the subject nicely. “What the West's Ancient Droughts Say About Its Future”:
Web Link
Another Palo Alto neighborhood
on Apr 8, 2015 at 2:51 pm
on Apr 8, 2015 at 2:51 pm
Supposing that annual rainfall will remain below normal for the foreseeable future and supposing that the population of California will grow, not counting all the tourists, etc., it is about time that some serious scientific and economics work was done to alleviate the problem.
From the scientific community, we need to find cost effective ways of producing usable water from both the ocean and gray water. Clean usable water will become the new gold for California so saying it is not cost effective is irrelevant. Market demands water, make it more expensive but plentiful and customers can choose how much to use and how to use it.
From the economics community, pricing and choice between fresh potable water and gray water will give choices to consumers.
Each household, business, farm,
etc. should be priced at various tiers. The first allocation of water should be the cheapest, but over a certain level the price goes up. Places like gyms, camping sites, etc. should charge for showers and the longer the shower, the more it costs. It is surprising if it costs you a second quarter (or whatever) for a longer shower then it will be relatively easy to turn off the shower while shaving or shampooing and then turning the water back on to rinse.
Then using gray water will also make sense. Hotels, etc. should be able to collect water from showers/laundry, etc. to use for toilet flushing, etc. Household adaption may be too expensive for existing homes, but all new housing should be built with these installations.
Just telling everyone to use less is going to make life very difficult. But getting sensible scientific and economics to look for solutions will make a difference.
East Palo Alto
on Apr 8, 2015 at 3:16 pm
on Apr 8, 2015 at 3:16 pm
"It's really hard to see much value in this particular study."
The reporter has summarized the article very well within the constraints of the medium. Here are the details: Web Link . TMI gripes will be gleefully ignored.
Registered user
Community Center
on Apr 8, 2015 at 3:20 pm
Registered user
on Apr 8, 2015 at 3:20 pm
@The WordHawk - You should tell Stanford that when they look at data for 120 years, and ignore the data for the thousands, or millions of years before that, their conclusions may be suspect.
Another Palo Alto neighborhood
on Apr 8, 2015 at 6:44 pm
on Apr 8, 2015 at 6:44 pm
The weather patterns have not changed that much in 150 years, when the "mini ice age" finally ended. Anyone who took California History in the fourth grade knows that CA has had cycles of drought and floods since the mid-1800s.
The problem is that most of California is either an arid or semi-arid region. Santa Clara County is semi-arid, and most of SoCal is arid--part of the Sonoran Desert. California simply cannot support the population it has on the precipitation it gets.
To make it worse, the Silicon Valley population has grown by leaps and bounds during this most recent drought. [Portion removed.]
Why don't the big companies just move to where there are healthier climates that can handle large populations, instead of sucking CA dry, literally? Like the Midwest?
Registered user
Community Center
on Apr 8, 2015 at 7:25 pm
Registered user
on Apr 8, 2015 at 7:25 pm
@The REAL problem - you are correct. The question will be whether it is easier to move people and businesses out, or to move water in.
Midtown
on Apr 8, 2015 at 11:01 pm
on Apr 8, 2015 at 11:01 pm
The droughts in the past may not hold as much significance as the one we're in now due to the growth of California's population.
Another Palo Alto neighborhood
on Apr 8, 2015 at 11:12 pm
on Apr 8, 2015 at 11:12 pm
Slow Down,
That's easy. It's a lot easier for people to move than building major new infrastructure to grow without bounds in an arid region like this. Actually, probably more to the point, it's a lot easier to stop building more without bounds that invites more people to move here.
Old Palo Alto
on Apr 9, 2015 at 12:11 am
on Apr 9, 2015 at 12:11 am
Scientists predicted many years ago that California was going to endure longer and more severe droughts, and depleted groundwater supplies.
I have sat through dozens of lectures about this at Stanford.
Why hasn't anyone proposed a pipeline like the Keystone XL to carry water to drier states on the West Coast?
Pipe in fresh water.
Companies like Apple, Google, Facebook, and Tesla could get the permits and funding going.
These corporations keep growing and importing more and more employees to make money for them. How about getting doing something to offset the environmental burden of all these people?
Just sayin'