1. Meteorological background

2. Impacts
    United States  California  Canada 

3. See also

4. References

5. External links

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The 2012–13 North American drought, an expansion of the 2010–13 Southern United States drought, originated in the midst of a record-breaking heat wave. Low snowfall amounts in winter, coupled with the intense summer heat from La Niña, caused drought-like conditions to migrate northward from the southern United States, wreaking havoc on crops and water supply.^[1] The drought has inflicted, and is expected to continue to inflict, catastrophic economic ramifications for the affected states. It has exceeded, in most measures, the 1988–89 North American drought, the most recent comparable drought, and is on track to exceed that drought as the costliest natural disaster in U.S. history.^[2]

The drought includes most of the U.S., parts of Mexico, and central and Eastern Canada. At its peak on July 17, 2012,{{citation needed|date=June 2014}} it covered approximately 81 percent of the contiguous United States with at least abnormally dry (D0) conditions. Out of that 81%, 64% was designated as at least moderate drought (D1) conditions.^[3] Its area was comparable to the droughts in the 1930s and 1950s but it has not yet been in place for as long.^[4] In March 2013, heavy winter rains broke a three-year pattern of drought in much of the Southeastern United States, while drought conditions still plague the Great Plains and other parts of the U.S., according to the U.S. Drought Monitor.^[5]

Drought continued in parts of North America through 2013.^[6] Beginning in March 2013, improved rainfall across the Midwest, southern Mississippi Valley, and Great Plains began gradually alleviating drought in these areas, while drought continued to intensify in the Western United States. Heavy rains across previously drought-stricken areas resulted in widespread flooding in portions of the Midwest, a phenomenon which was named "weather whiplash".^[7] By June 2013, approximately the eastern half of the United States was drought-free, while conditions continued to gradually improve across the Plains. Moderate to severe drought continues to impact and worsen throughout the western United States, with some portions of the United States being afflicted by the drought for over three years. Through the winter of 2013–2014, California continued to receive record low rainfall.^[8] For many locations, the calendar year of 2013 was the driest year in over 130 years. Some locations received less than half of their previous record low rainfall amounts.^[9]

Meteorological background

The drought was set in motion when strongly positive Arctic oscillation and North Atlantic oscillation conditions removed winter storms from the U.S. the winter of 2011–2012.^[10] When spring arrived, very little snow existed to melt and moisten the ground, and thus very little water to evaporate and create rainfall. The effects of the lack of snow were immediate. Dry conditions could be noticed immediately, and contributed to a weak tornado season in the U.S.^[11] The strongest tornado outbreak of 2012 occurred on March 2, after most snow had melted.^[12] The drought continued to steadily intensify along with a decline in rainfall which is still ongoing. The Summer 2012 North American heat wave caused further evaporation of groundwater, lakes, reservoirs, and rivers and streams.^[13]

As moisture has continued to decline, the conditions are becoming self-sustaining (i.e. a lack of rainfall means that less moisture is available to promote additional rainfall, in a vicious cycle).^[14] In many areas, the only way for drought conditions to be significantly alleviated in the short-term would be for a discrete, long-lived, and large system (such as a tropical cyclone) to impact the area.^[15] Soil hardening due to the drought means that even if a large amount of rain falls in a short time, most of it will run off quickly causing flash floods rather than drought relief. The June 2012 North American derecho and other strong storms in late June and early July did not appear to ease drought conditions, as the rainwater ran off rapidly from the affected areas.

The drought continued and intensified into the end of November 2014 for a large part of the country. Although drought/dry conditions are likely to drop at least one category level in the Southwest, Southeast, Northeast, and Northern Plains as well as portions of the Ohio River Valley, it is expected to have both short-term and long-term impacts across nearly the entire affected area.^[16][17]

A study by Utah State University analyzed the 2011 Missouri River Flooding ^[18] and predicted that "a prominent teleconnection forcing in driving the wet/dry spells in the (Missouri River Basin)... implies persistence of dry conditions for the next 2 to 3 years", which coincides with the 2012–15 drought. That analysis ^[18] was based upon a marked variability at the 10–15- year time scale that is coincident with the water storage increase in the Missouri River Basin. The study ^[19] found that precipitation over the MRB undergoes a profound modulation during the transition points of the Pacific quasi-decadal oscillation and associated teleconnections.

Impacts

United States

The drought has cost more than $35 billion in the Midwest, and is predicted to reduce the gross domestic product by 0.5–1% of the U.S. as a whole, equating to a loss of $75 to $150 billion.^[20]

Crops, particularly strains grown in the most heavily affected regions (such as corn and soybeans), have been noted to be failing or yielding very low this year due to the drought's presence in farming areas.^[21] This increase in cost will most likely move up the feeding chain and result in raised prices for meat, dairy, and processed food products.{{citation needed|date=May 2013}}Food prices are expected to rise dramatically because the resulting supply shortfall.^[22][23] The price of farm equipment, on the other hand, is expected to decrease as farmers are forced to sell off their equipment and machinery to cope with decreased incomes.^[24]

Parts of the Mississippi water levels have plummeted, affecting trade and commerce.^[25]

1,692 counties across 36 states in the U.S. have been legally declared primary natural disaster areas as of August 17 as the drought continues to cover 62% of the contiguous U.S.^[26] Hundreds of additional counties bordering the primary disaster areas are designated as "contiguous" disaster areas, and are also eligible for federal aid.

The number of cattle in the U.S. has been decreased to the lowest in 60 years due to drought impacts, with 69% of cattle located in areas currently facing drought conditions.^[27][28]

California

California had been experiencing a drought since 2011. In 2013 the total rainfall was less than 34% of what was expected. Many regions of the state accumulated less rainfall in 2013 than any other year on record. As a result of this, many fish species are threatened. Streams and rivers are so low that fish can't get to their spawning grounds, and survival rates of any eggs that are laid were expected to be low. Lack of rainfall has caused the mouths of rivers to be blocked off by sand bars which further prevents fish from reaching their spawning grounds. Stafford Lehr, Chief of Fisheries within the California Department of Fish and Wildlife says that 95% of winter run salmon didn't survive in 2013.^[29] Not only has the drought severely effected fishing, but also agriculture. Decreasing rainfall amounts and increasing temperatures cause agriculture to be much more challenging due to increasing rates of evapotranspiration^[30]

In response to heightening drought conditions, California has tightened fishing restrictions in many areas of the state. Streams and rivers on the northern coast have unprecedented amounts of fishing bans.^[32] In February 2015 the California Fish and Game Commission voted unanimously to further tighten regulations on both recreational and commercial fishing. The U.S. Endangered Species Act has listed steelhead as threatened and coho salmon as endangered.^[33] The California Department of Fish and Wildlife closed dozens of streams and rivers to fishing in 2014. Lehr has said that he fears coho salmon may go completely extinct south of the Golden Gate Bridge in the near future. In early 2014 the main stems of the Eel, Mad, Smith, Van Duzen, and Mattole rivers were closed pending additional rainfall. Large areas of the Russian and American rivers were closed indefinitely.^[32] Most rivers in San Mateo, Santa Cruz and Monterey counties were also closed pending further rainfall.^[32] Other actions have also been taken, such as releasing more water from the Kent Dam in hopes of raising the levels in the Lagunitas Creek watershed – one of the last spawning grounds that wild coho can still reach.^[31]

Protesters say that banning fishing will disrupt the economy and threaten the livelihoods of individuals who rely on salmon fishing during the winters. Officials feel that it will help prevent species that are already in trouble from slipping to extinction.^[32]

Canada

The drought affected Canada mainly in the east in Ontario, Quebec, and the Atlantic provinces where there was record setting heat and very little rainfall.^[33] Summer crops in these areas were affected and the price of produce, particularly corn and soybeans, was expected to increase.^[34][35]

See also

• Summer 2012 North American heat wave
• June 2012 North American derecho
• 2012 Oklahoma wildfires
• 2012 Colorado wildfires
• Climate change in California
• 2013 California wildfires
• 2014 California wildfires
• 2015 Puerto Rican drought

• Dust Bowl
• 1950s North American drought
• 1988 North American drought

References

External links

• Annual Drought Report for 2012, National Climatic Data Center, National Oceanic and Atmospheric Administration (NOAA)
• National Drought Mitigation Center
• Lifestyles of the Rich and Parched – How the Golden State’s 1 percenters are avoiding the drought, Politico magazine

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