4 February, 10:13

California drought continues: state dries up, no relief in sight

California drought continues: state dries up, no relief in sight

The California drought is reaching its 13th month and there is no sign of any relief in sight. The state is more than halfway through its wet season and the Sierra Nevada snowcap is practically non-existent this year, so California’s prospects for making up its precipitation deficit are slim.

The state authorities announced on Friday that for the first time in the 54-year history of the State Water Project they may not be able to allocate water to almost 25mln Californians who depend on the system of dams and reservoirs for additional water supplies. The Department of Water Resources is also planning to reduce allocations to farmland by 50 percent, which is the maximum extent allowed by the law.

The Department of Water Resources said that if Californians mean to cope with continued dry weather they must act now to preserve the water that still remains in their reservoirs.

California is the US most populous state with 38mln residents. It has a $44,7 billion agricultural industry that produces more than $100 billion in economic activity. California grows nearly half of all fruits, nuts and vegetables in the US and it is a leading dairy state. California farms heavily depend on irrigation to sustain production during the dry season, so drought is a serious threat to the state’s economy.

February and March are usually the last two months when California sees heavy rainfall before the dry season sets in. But in the past two years February was very dry and there is little hope of relief this year either, according to the National Weather Service. Water restrictions in many communities are already going into effect.

A dry spring also means a wildfire-filled summer.

The current drought started in January 2013 but at that time California had accumulated enough of a snowpack from a wet fall and an early winter to make it through the dry season. But this year has been the driest since 1895 and the snowpack water content is just 12 percent of the average for January, which is the record low, so the state has little reserve to fall back on.

Water managers are facing the most serious crisis since 1976-77 when the drought forced the state to institute a new system of water management policies. The current drought will provide a test of whether the mechanisms established then will work now in spite of considerable population growth and expansion of the agricultural sector.

The cause of the drought is an unusually intense and persistent area of high atmospheric pressure off the coast of British Columbia, which leaves California unusually warm and dry. The warmth is worsening the drought conditions with several monthly high temperature records broken.

The high pressure area known to meteorologists as a "resilient ridge" of high pressure is likely to remain in place through March. Scientists do not know why this resilient ridge of high pressure occurred in the first place. One of the explanations is the Pacific Decadal Oscillation which is a natural climate cycle involving the ocean and atmosphere in the Central and Northern Pacific Ocean. Global warming may also be making such blocking areas of high pressure.

According to scientists, high pressure areas must have favoured drought conditions in California in the distant past as well, such as medieval times. There are data that the first such drought period lasted between 850 AD and 1090 AD and the second one between 1140 AD and 1320 AD.

Although the forecasts do not offer much hope for drought relief, a sudden end to the drought is possible because it may be normal for California droughts to end suddenly. Climate scientists report that 33 to 40 percent of California droughts were ended by intense storms known as "atmospheric rivers" which can produce large amounts of precipitation across relatively narrow areas of the West. A majority of the West’s heavy rainfall and floods have been associated with atmospheric rivers.

Scientific research proves that atmospheric rivers can effectively end even severe droughts in California within just one month. This would seem to offer some hope to Californians but on the other hand, atmospheric river events are most common between November and March, so there is still reason for concern.

Manmade climate change is likely to add to the problem of drought conditions by increasing temperatures, which increases the evaporation of water from plants, soils and reservoirs. Studies show that although global warming may not trigger drought conditions, it is likely to worsen them.

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