California is Nuts

Last week, we looked at the fact that California has been in serious drought for the last few years, and touched on the implications this has for groundwater in the region. We also saw that the drought in California has been caused by a simple lack of rainfall. This week, we going to examine the drought a bit more detail, and focus on a key issue - farming.

I mentioned last time that water is important in California, because it has a lot of people and big urban areas like Los Angeles and San Francisco. However, in general, farming is the biggest water user in California. California is the breadbasket of the USA for fruits, vegetables and nuts. For some things, California pretty much single-handedly supplies the whole USA:

Credit: MotherJones

The drought map in this figure is out of date, and things are worse now (see last weeks post for the full picture), but it does aptly make the point that drought is a big issue for the USAs consumption of of some food products. Broccoli and walnuts are the worst offenders (this is some kind of culinary crimewatch) in terms of the water needed per 'unit' - 5.4 gallons are needed for one head of broccoli, and 4.9 gallons for one walnut.

Nuts are the most water draining, as so much water is needed for so little (one head of broccoli is a lot more than one walnut!).  Interestingly, almonds are the worst offender.

Credit: MotherJones

Almonds have become huge business - they are one of the lowest risk investments in the world, as their are so expensive and the price is unlikely to fall. As a result, more and more farmers in California are shifting to almonds and other tree nuts, simply because of their value and investment potential, and increasing demand from China. So, all the almonds produced in California need three times more water than all Los Angeles homes and business'. This really isn't just a theoretical idea - the Central Valley of California (the area that produce almonds) is the driest part of California, and has had the largest changes in well groundwater levels:

Credit: MotherJones

Again, a slightly outdated figure, but the picture it paints still applies. The Central Valley has been massively over-pumped, as nut orchards just keep expanding. Californian law is currently pretty lax on groundwater usages, to the extent that farmers can just drill into the ground and claim the groundwater as there. California is trying to change this, by managing access to all aquifers, but these rules wont come into effect for six years, and there is no way they will be an 'instant fix' - they are still weaker laws than many other Western states, and groundwater works on long, long timescales. Unsurprisingly, farm groups (and likely, the investors that back them) have not been too pleased to say the least, but their vested interests seem to be far less important than California's groundwater problem. 

So - California has got a bit of a problem on it's hands. Next week, we'll look at whether the drought is related to climate change, and if it is ever going to end.

Californication

There are approximately 196 countries in the world (political differences mean that not everyone recognises the same amount). California, just one state of 50 in the United States of America, has a population greater than all but the 34 most populated countries in the world - a population greater that 132 countries in the world.  Such a population requires a lot of water, particularly a resource hungry 'western' population, with huge urban areas like Los Angeles and San Francisco that have big water requirements. Unfortunately, that water simply hasn't been there - for the last four years, California has been gripped by drought. In April 2014, 100% of California was classed as being in drought, for the first time in at least 15 years:

It is notable that central southern USA were also in drought at the time. However, as the most recent picture shows, this area of the USA has recovered well.  However, for the Pacific Coast, there has been no recovery. In California, things have gone from bad to worse, with the majority of the state classed as being in exceptional or extreme drought:

Clearly, this is a difficult situation. The severity of the drought has necessitated implementation of the first mandatory water restrictions in the history of the state in April 2015, cities and towns being told to reduce consumption by 25%. Encouragingly, it was reported that Californian cities cut their water usage by 31.3% in July 2015, exceeding the mandatory water restrictions, rising steadily per month since the implementation in April 2015.

This is all very well and good - but why has California been in drought? Unsurprisingly, it is the simple matter that there has been a lack of rainfall. This has been caused by a persistent high pressure area over the Northeast Pacific Ocean, which has deflected winter storms and prevented them from depositing precipitation on California.

As a result of this lack of rainfall, California's reservoirs are nearly empty - in March 2015 it was estimated that there was one year of surface reservoir water left. This has lead to the use of an alternative source of water, particularly by agriculture: groundwater. Groundwater is a useful resource to have in dry times, but it takes a long time to be replenished once used. Nearly 75% of freshwater is now coming from groundwater in California, as there simply isn't enough surface water. This is a problem - if too much groundwater is used, and it runs out, it will take a very long time to replenish again. California needs to avoid using too much groundwater, but that is not easy when there is little rainfall - both surface water and groundwater stores are not being replenished.

Back in the Cycle

I haven't posted anything on this blog since January this year (I was busy finishing a degree), but I am going to be restarting the blog. Previously, the content had been very focused on climate change and river discharge, but it is my aim to expand the blog to cover the whole topic of climate change and water management.

With climate change ready to be debated by the world at the 2015 UN Climate Change Conference in Paris (also known as COP21), we are moving into an crucial period of potential political action on climate change. The conference aims to achieve a binding and universal agreement on climate change from all nations of the world, something which has proved impossible in the previous 20 years of UN negotiations - such an achievement would represent a defining moment in the 'fight' against climate change. I personally find it unlikely such an agreement will be reached, as there are some nations that still do not wish to engage with climate change (due to self interests, not doubt in the science), but I would be very happy to be proven wrong. The global political climate (pun not intended) appears to be far more suitable for such negotiations than the tense failure that was Copenhagen 2009, but nobody has entered the debating chamber yet. However, there are already concerns that anything agreed is likely to keep us below the 2C 'danger' threshold.

 

Water is a part of the hydrological cycle (see Fig 1), which hopefully is hopefully familiar. In simple terms, it is a big circle of water - water evaporates from the sea into the atmosphere, condenses and falls as precipitation, and makes its way back to the sea both on and within the ground. This is of course a gross simplification, but it is enough to make the point that all of these different parts of the cycle will be affected by climate change. This could lead to a variety of impacts, including droughts, floods, pollution, erosion, changes in water availability, just to name a few. Clearly, these are important impacts that could have a significant impacts on both humans and the environment. I hope to explore the different impacts in detail over time in this blog.

Hoping to aim for weekly posts, but obviously this will vary - sometimes more posts than once a week, sometimes less! 

Fig 1 - The Hydrological Cycle. | Credit - USGS.