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Wednesday, August 18, 2021

Dust Bowl

From Wikipedia, the free encyclopedia

Map of states and counties affected by the Dust Bowl between 1935 and 1938 originally prepared by the Soil Conservation Service. The most severely affected counties during this period are colored .
 
A farmer and his two sons during a dust storm in Cimarron County, Oklahoma, April 1936. Iconic photo taken by Arthur Rothstein.

The Dust Bowl was a period of severe dust storms that greatly damaged the ecology and agriculture of the American and Canadian prairies during the 1930s; severe drought and a failure to apply dryland farming methods to prevent the aeolian processes (wind erosion) caused the phenomenon. The drought came in three waves, 1934, 1936, and 1939–1940, but some regions of the High Plains experienced drought conditions for as many as eight years.

The Dust Bowl has been the subject of many cultural works, notably the novel The Grapes of Wrath (1939) by John Steinbeck, the folk music of Woody Guthrie, and photographs depicting the conditions of migrants by Dorothea Lange, particularly the Migrant Mother.

Geographic characteristics and early history

With insufficient understanding of the ecology of the plains, farmers had conducted extensive deep plowing of the virgin topsoil of the Great Plains during the previous decade; this had displaced the native, deep-rooted grasses that normally trapped soil and moisture even during periods of drought and high winds. The rapid mechanization of farm equipment, especially small gasoline tractors, and widespread use of the combine harvester contributed to farmers' decisions to convert arid grassland (much of which received no more than 10 inches (~250 mm) of precipitation per year) to cultivated cropland. During the drought of the 1930s, the unanchored soil turned to dust, which the prevailing winds blew away in huge clouds that sometimes blackened the sky. These choking billows of dust – named "black blizzards" or "black rollers" – traveled cross country, reaching as far as the East Coast and striking such cities as New York City and Washington, D.C. On the plains, they often reduced visibility to 3 feet (1 m) or less. Associated Press reporter Robert E. Geiger happened to be in Boise City, Oklahoma, to witness the "Black Sunday" black blizzards of April 14, 1935; Edward Stanley, the Kansas City news editor of the Associated Press, coined the term "Dust Bowl" while rewriting Geiger's news story.

While the term "the Dust Bowl" was originally a reference to the geographical area affected by the dust, today it usually refers to the event itself (the term "Dirty Thirties" is also sometimes used). The drought and erosion of the Dust Bowl affected 100,000,000 acres (400,000 km2) that centered on the panhandles of Texas and Oklahoma and touched adjacent sections of New Mexico, Colorado, and Kansas. The Dust Bowl forced tens of thousands of poverty-stricken families, who were unable to pay mortgages or grow crops, to abandon their farms, and losses reached $25 million per day by 1936 (equivalent to $470,000,000 in 2020). Many of these families, who were often known as "Okies" because so many of them came from Oklahoma, migrated to California and other states to find that the Great Depression had rendered economic conditions there little better than those they had left.

A dust storm approaches Stratford, Texas, in 1935.

The Dust Bowl area lies principally west of the 100th meridian on the High Plains, characterized by plains which vary from rolling in the north to flat in the Llano Estacado. Elevation ranges from 2,500 feet (760 m) in the east to 6,000 feet (1,800 m) at the base of the Rocky Mountains. The area is semiarid, receiving less than 20 inches (510 mm) of rain annually; this rainfall supports the shortgrass prairie biome originally present in the area. The region is also prone to extended drought, alternating with unusual wetness of equivalent duration. During wet years, the rich soil provides bountiful agricultural output, but crops fail during dry years. The region is also subject to high winds. During early European and American exploration of the Great Plains, this region was thought unsuitable for European-style agriculture; explorers called it the Great American Desert. The lack of surface water and timber made the region less attractive than other areas for pioneer settlement and agriculture.

The federal government encouraged settlement and development of the Plains for agriculture via the Homestead Act of 1862, offering settlers ”quarter section” 160-acre (65 ha) plots. With the end of the Civil War in 1865 and the completion of the First Transcontinental Railroad in 1869, waves of new migrants and immigrants reached the Great Plains, and they greatly increased the acreage under cultivation. An unusually wet period in the Great Plains mistakenly led settlers and the federal government to believe that "rain follows the plow" (a popular phrase among real estate promoters) and that the climate of the region had changed permanently. While initial agricultural endeavors were primarily cattle ranching, the adverse effect of harsh winters on the cattle, beginning in 1886, a short drought in 1890, and general overgrazing, led many landowners to increase the amount of land under cultivation.

Recognizing the challenge of cultivating marginal arid land, the United States government expanded on the 160 acres (65 ha) offered under the Homestead Act – granting 640 acres (260 ha) to homesteaders in western Nebraska under the Kinkaid Act (1904) and 320 acres (130 ha) elsewhere in the Great Plains under the Enlarged Homestead Act of 1909. Waves of European settlers arrived in the plains at the beginning of the 20th century. A return of unusually wet weather seemingly confirmed a previously held opinion that the "formerly" semiarid area could support large-scale agriculture. At the same time, technological improvements such as mechanized plowing and mechanized harvesting made it possible to operate larger properties without increasing labor costs.

The combined effects of the disruption of the Russian Revolution, which decreased the supply of wheat and other commodity crops, and World War I increased agricultural prices; this demand encouraged farmers to dramatically increase cultivation. For example, in the Llano Estacado of eastern New Mexico and northwestern Texas, the area of farmland was doubled between 1900 and 1920, then tripled again between 1925 and 1930. The agricultural methods favored by farmers during this period created the conditions for large-scale erosion under certain environmental conditions. The widespread conversion of the land by deep plowing and other soil preparation methods to enable agriculture eliminated the native grasses which held the soil in place and helped retain moisture during dry periods. Furthermore, cotton farmers left fields bare during winter months, when winds in the High Plains are highest, and burned the stubble as a means to control weeds prior to planting, thereby depriving the soil of organic nutrients and surface vegetation.

Drought and dust storms

A dust storm; Spearman, Texas, April 14, 1935
 
Heavy black clouds of dust rising over the Texas Panhandle, Texas, c. 1936

After fairly favorable climatic conditions in the 1920s with good rainfall and relatively moderate winters, which permitted increased settlement and cultivation in the Great Plains, the region entered an unusually dry era in the summer of 1930. During the next decade, the northern plains suffered four of their seven driest calendar years since 1895, Kansas four of its twelve driest, and the entire region south to West Texas lacked any period of above-normal rainfall until record rains hit in 1941. When severe drought struck the Great Plains region in the 1930s, it resulted in erosion and loss of topsoil because of farming practices at the time. The drought dried the topsoil and over time it became friable, reduced to a powdery consistency in some places. Without the indigenous grasses in place, the high winds that occur on the plains picked up the topsoil and created the massive dust storms that marked the Dust Bowl period. The persistent dry weather caused crops to fail, leaving the plowed fields exposed to wind erosion. The fine soil of the Great Plains was easily eroded and carried east by strong continental winds.

On November 11, 1933, a very strong dust storm stripped topsoil from desiccated South Dakota farmlands in one of a series of severe dust storms that year. Beginning on May 9, 1934, a strong, two-day dust storm removed massive amounts of Great Plains topsoil in one of the worst such storms of the Dust Bowl. The dust clouds blew all the way to Chicago, where they deposited 12 million pounds of dust (~ 5500 tonnes). Two days later, the same storm reached cities to the east, such as Cleveland, Buffalo, Boston, New York City, and Washington, D.C. That winter (1934–1935), red snow fell on New England.

On April 14, 1935, known as "Black Sunday", 20 of the worst "black blizzards" occurred across the entire sweep of the Great Plains, from Canada south to Texas. The dust storms caused extensive damage and appeared to turn the day to night; witnesses reported that they could not see five feet in front of them at certain points. Denver-based Associated Press reporter Robert E. Geiger happened to be in Boise City, Oklahoma, that day. His story about Black Sunday marked the first appearance of the term Dust Bowl; it was coined by Edward Stanley, Kansas City news editor of the Associated Press, while rewriting Geiger's news story.

Spearman and Hansford County have been literaly [sic] in a cloud of dust for the past week. Ever since Friday of last week, there hasn't been a day pass but what the county was beseieged [sic] with a blast of wind and dirt. On rare occasions when the wind did subside for a period of hours, the air has been so filled with dust that the town appeared to be overhung by a fog cloud. Because of this long seige of dust and every building being filled with it, the air has become stifling to breathe and many people have developed sore throats and dust colds as a result.

— Spearman Reporter, March 21, 1935

Much of the farmland was eroded in the aftermath of the Dust Bowl. In 1941, a Kansas agricultural experiment station released a bulletin that suggested reestablishing native grasses by the "hay method". Developed in 1937 to speed up the process and increase returns from pasture, the "hay method" was originally supposed to occur in Kansas naturally over 25–40 years. After much data analysis, the causal mechanism for the droughts can be linked to ocean temperature anomalies. Specifically, Atlantic Ocean sea surface temperatures appear to have had an indirect effect on the general atmospheric circulation, while Pacific sea surface temperatures seem to have had the most direct influence.

Human displacement

Buried machinery in a barn lot; Dallas, South Dakota, May 1936

This catastrophe intensified the economic impact of the Great Depression in the region.

In 1935, many families were forced to leave their farms and travel to other areas seeking work because of the drought (which at that time had already lasted four years). The abandonment of homesteads and financial ruin resulting from catastrophic topsoil loss led to widespread hunger and poverty. Dust Bowl conditions fomented an exodus of the displaced from Texas, Oklahoma, and the surrounding Great Plains to adjacent regions. More than 500,000 Americans were left homeless. More than 350 houses had to be torn down after one storm alone. The severe drought and dust storms had left many homeless; others had their mortgages foreclosed by banks, or felt they had no choice but to abandon their farms in search of work. Many Americans migrated west looking for work. Parents packed up "jalopies" with their families and a few personal belongings, and headed west in search of work. Some residents of the Plains, especially in Kansas and Oklahoma, fell ill and died of dust pneumonia or malnutrition.

"Broke, baby sick, and car trouble!"Dorothea Lange's 1937 photo of a Missouri migrant family's jalopy stuck near Tracy, California.

The Dust Bowl exodus was the largest migration in American history within a short period of time. Between 1930 and 1940, approximately 3.5 million people moved out of the Plains states; of those, it is unknown how many moved to California. In just over a year, over 86,000 people migrated to California. This number is more than the number of migrants to that area during the 1849 Gold Rush. Migrants abandoned farms in Oklahoma, Arkansas, Missouri, Iowa, Nebraska, Kansas, Texas, Colorado, and New Mexico, but were often generally referred to as "Okies", "Arkies", or "Texies". Terms such as "Okies" and "Arkies" came to be known in the 1930s as the standard terms for those who had lost everything and were struggling the most during the Great Depression.

A migratory family from Texas living in a trailer in an Arizona cotton field

Not all migrants traveled long distances; some simply went to the next town or county. So many families left their farms and were on the move that the proportion between migrants and residents was nearly equal in the Great Plains states.

Historian James N. Gregory examined Census Bureau statistics and other records to learn more about the migrants. Based on a 1939 survey of occupation by the Bureau of Agricultural Economics of about 116,000 families who arrived in California in the 1930s, he learned that only 43 percent of southwesterners were doing farm work immediately before they migrated. Nearly one-third of all migrants were professional or white-collar workers. The poor economy displaced more than just farmers as refugees to California; many teachers, lawyers, and small business owners moved west with their families during this time. After the Great Depression ended, some moved back to their original states. Many others remained where they had resettled. About one-eighth of California's population is of Okie heritage.

Government response

The greatly expanded participation of government in land management and soil conservation was an important outcome from the disaster. Different groups took many different approaches to responding to the disaster. To identify areas that needed attention, groups such as the Soil Conservation Service generated detailed soil maps and took photos of the land from the sky. To create shelterbelts to reduce soil erosion, groups such as the United States Forestry Service's Prairie States Forestry Project planted trees on private lands. Finally, groups like the Resettlement Administration, which later became the Farm Security Administration, encouraged small farm owners to resettle on other lands, if they lived in drier parts of the Plains.

During President Franklin D. Roosevelt's first 100 days in office in 1933, his administration quickly initiated programs to conserve soil and restore the ecological balance of the nation. Interior Secretary Harold L. Ickes established the Soil Erosion Service in August 1933 under Hugh Hammond Bennett. In 1935, it was transferred and reorganized under the Department of Agriculture and renamed the Soil Conservation Service. It is now known as the Natural Resources Conservation Service (NRCS).

As part of New Deal programs, Congress passed the Soil Conservation and Domestic Allotment Act in 1936, requiring landowners to share the allocated government subsidies with the laborers who worked on their farms. Under the law, "benefit payments were continued as measures for production control and income support, but they were now financed by direct Congressional appropriations and justified as soil conservation measures. The Act shifted the parity goal from price equality of agricultural commodities and the articles that farmers buy to income equality of farm and non-farm population." Thus, the parity goal was to re-create the ratio between the purchasing power of the net income per person on farms from agriculture and that of the income of persons not on farms that prevailed during 1909–1914.

To stabilize prices, the government paid farmers and ordered more than six million pigs to be slaughtered, as part of the Agricultural Adjustment Act (AAA). It paid to have the meat packed and distributed to the poor and hungry. The Federal Surplus Relief Corporation (FSRC) was established to regulate crop and other surpluses. FDR in an address on May 14, 1935, to the AAA commented,

Let me make one other point clear for the benefit of the millions in cities who have to buy meats. Last year the Nation suffered a drought of unparalleled intensity. If there had been no Government program, if the old order had obtained in 1933 and 1934, that drought on the cattle ranges of America and in the corn belt would have resulted in the marketing of thin cattle, immature hogs and the death of these animals on the range and on the farm, and if the old order had been in effect those years, we would have had a vastly greater shortage than we face today. Our program – we can prove it – saved the lives of millions of head of livestock. They are still on the range, and other millions of heads are today canned and ready for this country to eat.

The FSRC diverted agricultural commodities to relief organizations. Apples, beans, canned beef, flour and pork products were distributed through local relief channels. Cotton goods were later included, to clothe needy.

In 1935, the federal government formed a Drought Relief Service (DRS) to coordinate relief activities. The DRS bought cattle in counties which were designated emergency areas, for $14 to $20 a head. Animals determined unfit for human consumption were killed; at the beginning of the program, more than 50 percent were so designated in emergency areas. The DRS assigned the remaining cattle to the Federal Surplus Relief Corporation (FSRC) to be used in food distribution to families nationwide. Although it was difficult for farmers to give up their herds, the cattle slaughter program helped many of them avoid bankruptcy. "The government cattle buying program was a blessing to many farmers, as they could not afford to keep their cattle, and the government paid a better price than they could obtain in local markets."

President Roosevelt ordered the Civilian Conservation Corps to plant the Great Plains Shelterbelt, a huge belt of more than 200 million trees from Canada to Abilene, Texas to break the wind, hold water in the soil, and hold the soil itself in place. The administration also began to educate farmers on soil conservation and anti-erosion techniques, including crop rotation, strip farming, contour plowing, terracing, and other improved farming practices. In 1937, the federal government began an aggressive campaign to encourage farmers in the Dust Bowl to adopt planting and plowing methods that conserved the soil. The government paid reluctant farmers a dollar an acre to practice the new methods. By 1938, the massive conservation effort had reduced the amount of blowing soil by 65%. The land still failed to yield a decent living. In the fall of 1939, after nearly a decade of dirt and dust, the drought ended when regular rainfall finally returned to the region. The government still encouraged continuing the use of conservation methods to protect the soil and ecology of the Plains.

At the end of the drought, the programs which were implemented during these tough times helped to sustain a positive relationship between America's farmers and the federal government.

The President's Drought Committee issued a report in 1935 covering the government's assistance to agriculture during 1934 through mid-1935: it discussed conditions, measures of relief, organization, finances, operations, and results of the government's assistance. Numerous exhibits are included in this report.

Long-term economic impact

In many regions, more than 75% of the topsoil was blown away by the end of the 1930s. Land degradation varied widely. Aside from the short-term economic consequences caused by erosion, there were severe long-term economic consequences caused by the Dust Bowl.

By 1940, counties that had experienced the most significant levels of erosion had a greater decline in agricultural land values. The per-acre value of farmland declined by 28% in high-erosion counties and 17% in medium-erosion counties, relative to land value changes in low-erosion counties. Even over the long-term, the agricultural value of the land often failed to recover to pre-Dust Bowl levels. In highly eroded areas, less than 25% of the original agricultural losses were recovered. The economy adjusted predominantly through large relative population declines in more-eroded counties, both during the 1930s and through the 1950s.

The economic effects persisted, in part, because of farmers' failure to switch to more appropriate crops for highly eroded areas. Because the amount of topsoil had been reduced, it would have been more productive to shift from crops and wheat to animals and hay. During the Depression and through at least the 1950s, there was limited relative adjustment of farmland away from activities that became less productive in more-eroded counties.

Some of the failure to shift to more productive agricultural products may be related to ignorance about the benefits of changing land use. A second explanation is a lack of availability of credit, caused by the high rate of failure of banks in the Plains states. Because banks failed in the Dust Bowl region at a higher rate than elsewhere, farmers could not get the credit they needed to obtain capital to shift crop production. In addition, profit margins in either animals or hay were still minimal, and farmers had little incentive in the beginning to change their crops.

Patrick Allitt recounts how fellow historian Donald Worster responded to his return visit to the Dust Bowl in the mid-1970s when he revisited some of the worst afflicted counties:

Capital-intensive agribusiness had transformed the scene; deep wells into the aquifer, intensive irrigation, the use of artificial pesticides and fertilizers, and giant harvesters were creating immense crops year after year whether it rained or not. According to the farmers he interviewed, technology had provided the perfect answer to old troubles, such of the bad days would not return. In Worster's view, by contrast, the scene demonstrated that America's capitalist high-tech farmers had learned nothing. They were continuing to work in an unsustainable way, devoting far cheaper subsidized energy to growing food than the energy could give back to its ultimate consumers.

In contrast with Worster's pessimism, historian Mathew Bonnifield argued that the long-term significance of the Dust Bowl was "the triumph of the human spirit in its capacity to endure and overcome hardships and reverses."

Influence on the arts and culture

Florence Owens Thompson seen in the photo Destitute Pea Pickers in California. Mother of Seven Children. by Dorothea Lange
 
"Dust bowl farmers of west Texas in town", photograph by Dorothea Lange, June 1937.

The crisis was documented by photographers, musicians, and authors, many hired during the Great Depression by the federal government. For instance, the Farm Security Administration hired numerous photographers to document the crisis. Artists such as Dorothea Lange were aided by having salaried work during the Depression. She captured what have become classic images of the dust storms and migrant families. Among her most well-known photographs is Destitute Pea Pickers in California. Mother of Seven Children, which depicted a gaunt-looking woman, Florence Owens Thompson, holding three of her children. This picture expressed the struggles of people caught by the Dust Bowl and raised awareness in other parts of the country of its reach and human cost. Decades later, Thompson disliked the boundless circulation of the photo and resented the fact she did not receive any money from its broadcast. Thompson felt it gave her the perception as a Dust Bowl "Okie."

The work of independent artists was also influenced by the crises of the Dust Bowl and the Depression. Author John Steinbeck, borrowing closely from field notes taken by Farm Security Administration worker and author Sanora Babb, wrote The Grapes of Wrath (1939) about migrant workers and farm families displaced by the Dust Bowl. Babb's own novel about the lives of the migrant workers, Whose Names Are Unknown, was written in 1939 but was eclipsed and shelved in response to the success of Steinbeck's work, and was finally published in 2004. Many of the songs of folk singer Woody Guthrie, such as those on his 1940 album Dust Bowl Ballads, are about his experiences in the Dust Bowl era during the Great Depression when he traveled with displaced farmers from Oklahoma to California and learned their traditional folk and blues songs, earning him the nickname the "Dust Bowl Troubadour".

Migrants also influenced musical culture wherever they went. Oklahoma migrants, in particular, were rural Southwesterners who carried their traditional country music to California. Today, the "Bakersfield Sound" describes this blend, which developed after the migrants brought country music to the city. Their new music inspired a proliferation of country dance halls as far south as Los Angeles.

The 2014 science fiction film Interstellar features a ravaged 21st-century America which is again scoured by dust storms (caused by a worldwide pathogen affecting all crops). Along with inspiration from the 1930s crisis, director Christopher Nolan features interviews from the 2012 documentary The Dust Bowl to draw further parallels.

In 2017, Americana recording artist Grant Maloy Smith released the album Dust Bowl – American Stories, which was inspired by the history of the Dust Bowl. In a review, the music magazine No Depression wrote that the album's lyrics and music are "as potent as Woody Guthrie, as intense as John Trudell and dusted with the trials and tribulations of Tom Joad – Steinbeck and The Grapes of Wrath."

Aggregate changes in agriculture and population on the Plains

The change in the total value of agricultural land and revenue was quite similar over the twentieth century. Agricultural land and revenue boomed during World War I, but fell during the Great Depression and the 1930s. The land and revenue began increasing again in 1940, and has been increasing since then. From 1910 to the 1940s, total farmland increased and remained constant until 1970 when it slightly declined. During this time, total population increased steadily, but there was a slight dip in trend from 1930 to 1960.

 

1936 North American heat wave

From Wikipedia, the free encyclopedia
 
Summer (June–August) 1936 average temperature, in degrees Fahrenheit. Record warmest and coldest is based on a 112-year period of records (1895–2006).

The 1936 North American heat wave was one of the most severe heat waves in the modern history of North America. It took place in the middle of the Great Depression and Dust Bowl of the 1930s and caused catastrophic human suffering and an enormous economic toll. The death toll exceeded 5,000, and huge numbers of crops were destroyed by the heat and lack of moisture. Many state and city record high temperatures set during the 1936 heat wave stood until the summer 2012 North American heat wave. The 1936 heat wave followed one of the coldest winters on record.

Events

Summer (June–August) 1936 precipitation, in inches. Record wettest and driest is based on a 112-year period of records (1895–2006).

The heat wave started in late June, when temperatures across the United States exceeded 100 °F (38 °C). The Midwest experienced some of the highest June temperatures on record. Drought conditions worsened. In the Northeast, temperatures climbed to the mid 90s °F (around 35 °C). The South and West started to heat up as well, and also experienced drought. The heat wave began to extend into Canada. Moderate to extreme drought covered the entire continent. The dry and exposed soil contributed directly to the heat (as happens normally in desert areas), as the extreme heat entered the air by radiation and direct contact.

July was the peak month, in which temperatures reached all-time records—many of which still stood as of 2012. In Steele, North Dakota, temperatures reached 121 °F (49 °C), which remains North Dakota's record. In Ohio, temperatures reached 110 °F (43 °C), which nearly tied the previous record set in 1934. The states of Texas, Oklahoma, Kansas, Arkansas, Minnesota, Michigan, North Dakota, South Dakota, Pennsylvania, Louisiana, Nebraska, Wisconsin, West Virginia, and New Jersey also experienced record high temperatures. The provinces of Ontario and Manitoba set still-standing record highs above 110 °F (43 °C). Chicago Midway Airport recorded 100 °F (38 °C) or higher temperatures on eight consecutive days from July 7–14, 1936. Later that summer in downstate Illinois, at Mount Vernon, the temperature surpassed 100 °F (38 °C) for 18 days running from August 12–29, 1936.

Some stations in the American Midwest reported minimum temperatures at or above 90 °F (32 °C), such as 91 °F (33 °C) at Lincoln, Nebraska, on July 25, 1936; the next and most recent time this is known to have happened is during a similar, but far less intense, heat wave in late June 1988 that produced a handful of 90 °F (32 °C) minimums. The highest nightly low temperature outside the Desert Southwest was 94 °F (34 °C) at Atchison, Kansas, during the heat wave of July 1934.

August was the warmest month on record for five states. Many experienced long stretches of daily maximum temperatures 100 °F (38 °C) or warmer. Drought conditions worsened in some locations. Other states were only slightly warmer than average.

The heat wave and drought largely ended in September, though many states were still drier and warmer than average. Many farmers' summer harvests were destroyed. Grounds and lawns remained parched. Seasonable temperatures returned in the autumn.

Summer 1936 still remains the warmest summer on record in the USA (since official records begin in 1895). However February 1936 was the coldest February on record, and 5 of the 12 months were below average, leaving the full year 1936 at just above the average.

Effects

As many as 5,000 heat-related deaths were reported in the United States, and 780 direct and 400 indirect deaths in Canada. Many people suffered from heat stroke and heat exhaustion, particularly the elderly. Unlike today, air conditioning was in the early stages of development and was therefore absent from houses and commercial buildings. Many of the deaths occurred in high-population-density areas of Chicago, Detroit, St. Louis, Milwaukee, Cleveland, Toronto, and other urban areas. Farmers across the continent saw crop failure, causing corn and wheat prices to rise quickly. Droughts and heat waves were common in the 1930s. The 1930s (the Dust Bowl years) are remembered as the driest and warmest decade for the United States, and the summer of 1936 featured the most widespread and destructive heat wave to occur in the Americas in centuries.

 

Heat wave

From Wikipedia, the free encyclopedia

A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual weather in the area and relative to normal temperatures for the season. Temperatures that people from a hotter climate consider normal can be called a heat wave in a cooler area if they are outside the normal climate pattern for that area.

The term is applied both to hot weather variations and to extraordinary spells of hot which may occur only once a century. Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning. A heat wave is considered extreme weather that can be a natural disaster, and a danger because heat and sunlight may overheat the human body. Heat waves can usually be detected using forecasting instruments so that a warning call can be issued.

Definitions

A definition based on Frich et al.'s Heat Wave Duration Index is that a heat wave occurs when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C (9 °F), the normal period being 1961–1990.

A formal, peer-reviewed definition from the Glossary of Meteorology is:

A period of abnormally and uncomfortably hot and usually humid weather.

To be a heat wave such a period should last at least one day, but conventionally it lasts from several days to several weeks. In 1900, A. T. Burrows more rigidly defined a "hot wave" as a spell of three or more days on each of which the maximum shade temperature reaches or exceeds 90 °F (32.2 °C). More realistically, the comfort criteria for any one region are dependent upon the normal conditions of that area.

The World Meteorological Organization, defines a heat wave as five or more consecutive days of prolonged heat in which the daily maximum temperature is higher than the average maximum temperature by 5 °C (9 °F) or more. However, some nations have come up with their own criteria to define a heat wave.

Temperature anomalies, March to May 2007

In the Netherlands, a heat wave is defined as a period of at least five consecutive days in which the maximum temperature in De Bilt exceeds 25 °C (77 °F), provided that on at least three days in this period the maximum temperature in De Bilt exceeds 30 °C (86 °F). This definition of a heat wave is also used in Belgium and Luxembourg.

In Denmark, a national heat wave (hedebølge) is defined as a period of at least 3 consecutive days of which period the average maximum temperature across more than fifty percent of the country exceeds 28 °C (82.4 °F) – the Danish Meteorological Institute further defines a "warmth wave" (varmebølge) when the same criteria are met for a 25 °C (77.0 °F) temperature, while in Sweden, a heat wave is defined as at least five days in a row with a daily high exceeding 25 °C (77.0 °F).

In the United States, definitions also vary by region; however, a heat wave is usually defined as a period of at least two or more days of excessively hot weather. In the Northeast, a heat wave is typically defined as three consecutive days where the temperature reaches or exceeds 90 °F (32.2 °C), but not always as this ties in with humidity levels to determine a heat index threshold. The same does not apply to drier climates. A heat storm is a Californian term for an extended heat wave. Heat storms occur when the temperature reaches 100 °F (37.8 °C) for three or more consecutive days over a wide area (tens of thousands of square miles). The National Weather Service issues heat advisories and excessive heat warnings when unusual periods of hot weather are expected.

In Adelaide, South Australia, a heat wave is defined as five consecutive days at or above 35 °C (95 °F), or three consecutive days at or over 40 °C (104 °F). The Australian Bureau of Meteorology defines a heat wave as "three days or more of maximum and minimum temperatures that are unusual for the location". Until the introduction of this new Pilot Heatwave Forecast there was no national definition that described heatwave or measures of heatwave severity.

In Greece, according to the Hellenic National Metereological Service, a heat wave is defined as three consecutive days at or above 39 °C (102 °F) and a minimum temperature in the same period at or over 26 °C (79 °F), with no winds or with weak winds, and the above conditions being observed in a broad area.

In the United Kingdom, the Met Office operates a Heat Health Watch system which places each Local Authority region into one of four levels. Heatwave conditions are defined by the maximum daytime temperature and minimum nighttime temperature rising above the threshold for a particular region. The length of time spent above that threshold determines the particular level. Level 1 is normal summer conditions. Level 2 is reached when there is a 60% or higher risk that the temperature will be above the threshold levels for two days and the intervening night. Level 3 is triggered when the temperature has been above the threshold for the preceding day and night, and there is a 90% or higher chance that it will stay above the threshold in the following day. Level 4 is triggered if conditions are more severe than those of the preceding three levels. Each of the first three levels is associated with a particular state of readiness and response by the social and health services, and Level 4 is associated with more widespread response.

A more general indicator that allows comparing heat waves in different regions of the World, characterized by different climates, was published in 2015. This was used to estimate heat waves occurrence at the global scale from 1901 to 2010, finding a substantial and sharp increase in the number of affected areas in the last two decades.

Heat Waves from 1901 to 2010.gif

Formation

High pressure in the upper atmosphere traps heat near the ground, forming a heat wave

Heat waves form when high pressure aloft (from 10,000–25,000 feet (3,000–7,600 metres)) strengthens and remains over a region for several days up to several weeks. This is common in summer (in both Northern and Southern Hemispheres) as the jet stream 'follows the sun'. On the equator side of the jet stream, in the upper layers of the atmosphere, is the high pressure area.

Summertime weather patterns are generally slower to change than in winter. As a result, this upper level high pressure also moves slowly. Under high pressure, the air subsides (sinks) toward the surface, warming and drying adiabatically, inhibiting convection and preventing the formation of clouds. Reduction of clouds increases shortwave radiation reaching the surface. A low pressure at the surface leads to surface wind from lower latitudes that brings warm air, enhancing the warming. Alternatively, the surface winds could blow from the hot continental interior towards the coastal zone, leading to heat waves there, or from a high elevation towards low elevation, enhancing the subsidence and therefore the adiabatic warming.

In the Eastern United States a heat wave can occur when a high pressure system originating in the Gulf of Mexico becomes stationary just off the Atlantic Seaboard (typically known as a Bermuda High). Hot humid air masses form over the Gulf of Mexico and the Caribbean Sea while hot dry air masses form over the desert Southwest and northern Mexico. The SW winds on the back side of the High continue to pump hot, humid Gulf air northeastward resulting in a spell of hot and humid weather for much of the Eastern States.

In the Western Cape Province of South Africa, a heat wave can occur when a low pressure offshore and high pressure inland air combine to form a Bergwind. The air warms as it descends from the Karoo interior, and the temperature will rise about 10 °C from the interior to the coast. Humidities are usually very low, and the temperatures can be over 40 °C in summer. The highest official temperatures recorded in South Africa (51.5 °C) was recorded one summer during a bergwind occurring along the Eastern Cape coastline.

Global warming boosts the probability of extreme weather events, like heat waves, far more than it boosts more moderate events.

Health effects

NOAA national weather service: heat index
Tempera-
ture
Relative
humidity
80 °F (27 °C) 82 °F (28 °C) 84 °F (29 °C) 86 °F (30 °C) 88 °F (31 °C) 90 °F (32 °C) 92 °F (33 °C) 94 °F (34 °C) 96 °F (36 °C) 98 °F (37 °C) 100 °F (38 °C) 102 °F (39 °C) 104 °F (40 °C) 106 °F (41 °C) 108 °F (42 °C) 110 °F (43 °C)
40% 80 °F (27 °C) 81 °F (27 °C) 83 °F (28 °C) 85 °F (29 °C) 88 °F (31 °C) 91 °F (33 °C) 94 °F (34 °C) 97 °F (36 °C) 101 °F (38 °C) 105 °F (41 °C) 109 °F (43 °C) 114 °F (46 °C) 119 °F (48 °C) 124 °F (51 °C) 130 °F (54 °C) 136 °F (58 °C)
45% 80 °F (27 °C) 82 °F (28 °C) 84 °F (29 °C) 87 °F (31 °C) 89 °F (32 °C) 93 °F (34 °C) 96 °F (36 °C) 100 °F (38 °C) 104 °F (40 °C) 109 °F (43 °C) 114 °F (46 °C) 119 °F (48 °C) 124 °F (51 °C) 130 °F (54 °C) 137 °F (58 °C)
50% 81 °F (27 °C) 83 °F (28 °C) 85 °F (29 °C) 88 °F (31 °C) 91 °F (33 °C) 95 °F (35 °C) 99 °F (37 °C) 103 °F (39 °C) 108 °F (42 °C) 113 °F (45 °C) 118 °F (48 °C) 124 °F (51 °C) 131 °F (55 °C) 137 °F (58 °C)

55% 81 °F (27 °C) 84 °F (29 °C) 86 °F (30 °C) 89 °F (32 °C) 93 °F (34 °C) 97 °F (36 °C) 101 °F (38 °C) 106 °F (41 °C) 112 °F (44 °C) 117 °F (47 °C) 124 °F (51 °C) 130 °F (54 °C) 137 °F (58 °C)


60% 82 °F (28 °C) 84 °F (29 °C) 88 °F (31 °C) 91 °F (33 °C) 95 °F (35 °C) 100 °F (38 °C) 105 °F (41 °C) 110 °F (43 °C) 116 °F (47 °C) 123 °F (51 °C) 129 °F (54 °C) 137 °F (58 °C)



65% 82 °F (28 °C) 85 °F (29 °C) 89 °F (32 °C) 93 °F (34 °C) 98 °F (37 °C) 103 °F (39 °C) 108 °F (42 °C) 114 °F (46 °C) 121 °F (49 °C) 128 °F (53 °C) 136 °F (58 °C)




70% 83 °F (28 °C) 86 °F (30 °C) 90 °F (32 °C) 95 °F (35 °C) 100 °F (38 °C) 105 °F (41 °C) 112 °F (44 °C) 119 °F (48 °C) 126 °F (52 °C) 134 °F (57 °C)





75% 84 °F (29 °C) 88 °F (31 °C) 92 °F (33 °C) 97 °F (36 °C) 103 °F (39 °C) 109 °F (43 °C) 116 °F (47 °C) 124 °F (51 °C) 132 °F (56 °C)






80% 84 °F (29 °C) 89 °F (32 °C) 94 °F (34 °C) 100 °F (38 °C) 106 °F (41 °C) 113 °F (45 °C) 121 °F (49 °C) 129 °F (54 °C)







85% 85 °F (29 °C) 90 °F (32 °C) 96 °F (36 °C) 102 °F (39 °C) 110 °F (43 °C) 117 °F (47 °C) 126 °F (52 °C) 135 °F (57 °C)







90% 86 °F (30 °C) 91 °F (33 °C) 98 °F (37 °C) 105 °F (41 °C) 113 °F (45 °C) 122 °F (50 °C) 131 °F (55 °C)








95% 86 °F (30 °C) 93 °F (34 °C) 100 °F (38 °C) 108 °F (42 °C) 117 °F (47 °C) 127 °F (53 °C)









100% 87 °F (31 °C) 95 °F (35 °C) 103 °F (39 °C) 112 °F (44 °C) 121 °F (49 °C) 132 °F (56 °C)









Key to colors:   Caution   Extreme caution   Danger   Extreme danger

The heat index (as shown in the table above) is a measure of how hot it feels when relative humidity is factored with the actual air temperature. Hyperthermia, also known as heat stroke, becomes commonplace during periods of sustained high temperature and humidity. Older adults, very young children, and those who are sick or overweight are at a higher risk for heat-related illness. The chronically ill and elderly are often taking prescription medications (e.g., diuretics, anticholinergics, antipsychotics, and antihypertensives) that interfere with the body's ability to dissipate heat.

Heat edema presents as a transient swelling of the hands, feet, and ankles and is generally secondary to increased aldosterone secretion, which enhances water retention. When combined with peripheral vasodilation and venous stasis, the excess fluid accumulates in the dependent areas of the extremities. The heat edema usually resolves within several days after the patient becomes acclimated to the warmer environment. No treatment is required, although wearing support stockings and elevating the affected legs will help minimize the edema.

Heat rash, also known as prickly heat, is a maculopapular rash accompanied by acute inflammation and blocked sweat ducts. The sweat ducts may become dilated and may eventually rupture, producing small pruritic vesicles on an erythematous base. Heat rash affects areas of the body covered by tight clothing. If this continues for a duration of time it can lead to the development of chronic dermatitis or a secondary bacterial infection. Prevention is the best therapy. It is also advised to wear loose-fitting clothing in the heat. However, once heat rash has developed, the initial treatment involves the application of chlorhexidine lotion to remove any desquamated skin. The associated itching may be treated with topical or systemic antihistamines. If infection occurs a regimen of antibiotics is required.

The 1936 North American heat wave. Record temperatures were based on 112-year records

Heat cramps are painful, often severe, involuntary spasms of the large muscle groups used in strenuous exercise. Heat cramps tend to occur after intense exertion. They usually develop in people performing heavy exercise while sweating profusely and replenishing fluid loss with non-electrolyte containing water. This is believed to lead to hyponatremia that induces cramping in stressed muscles. Rehydration with salt-containing fluids provides rapid relief. Patients with mild cramps can be given oral .2% salt solutions, while those with severe cramps require IV isotonic fluids. The many sport drinks on the market are a good source of electrolytes and are readily accessible.

Heat syncope is related to heat exposure that produces orthostatic hypotension. This hypotension can precipitate a near-syncopal episode. Heat syncope is believed to result from intense sweating, which leads to dehydration, followed by peripheral vasodilation and reduced venous blood return in the face of decreased vasomotor control. Management of heat syncope consists of cooling and rehydration of the patient using oral rehydration therapy (sport drinks) or isotonic IV fluids. People who experience heat syncope should avoid standing in the heat for long periods of time. They should move to a cooler environment and lie down if they recognize the initial symptoms. Wearing support stockings and engaging in deep knee-bending movements can help promote venous blood return.

Heat exhaustion is considered by experts to be the forerunner of heat stroke (hyperthermia). It may even resemble heat stroke, with the difference being that the neurologic function remains intact. Heat exhaustion is marked by excessive dehydration and electrolyte depletion. Symptoms may include diarrhea, headache, nausea and vomiting, dizziness, tachycardia, malaise, and myalgia. Definitive therapy includes removing patients from the heat and replenishing their fluids. Most patients will require fluid replacement with IV isotonic fluids at first. The salt content is adjusted as necessary once the electrolyte levels are known. After discharge from the hospital, patients are instructed to rest, drink plenty of fluids for 2–3 hours, and avoid the heat for several days. If this advice is not followed it may then lead to heat stroke.

One public health measure taken during heat waves is the setting-up of air-conditioned public cooling centers.

Mortality

Heat waves are the most lethal type of weather phenomenon in the United States. Between 1992 and 2001, deaths from excessive heat in the United States numbered 2,190, compared with 880 deaths from floods and 150 from hurricanes. The average annual number of fatalities directly attributed to heat in the United States is about 400. The 1995 Chicago heat wave, one of the worst in US history, led to approximately 739 heat-related deaths over a period of 5 days. Eric Klinenberg has noted that in the United States, the loss of human life in hot spells in summer exceeds that caused by all other weather events combined, including lightning, rain, floods, hurricanes, and tornadoes. Despite the dangers, Scott Sheridan, professor of geography at Kent State University, found that less than half of people 65 and older abide by heat-emergency recommendations such as drinking plenty of water. In his study of heat-wave behavior, focusing particularly on seniors in Philadelphia, Phoenix, Toronto, and Dayton, Ohio, he found that people over 65 "don't consider themselves seniors." One of his older respondents said: "Heat doesn't bother me much, but I worry about my neighbors."

According to the Agency for Health care Research and Quality, about 6,200 Americans are hospitalized each summer due to excessive heat, and those at highest risk are poor, uninsured or elderly. More than 70,000 Europeans died as a result of the 2003 European heat wave. Also more than 2,000 people died in Karachi, Pakistan in June 2015 due to a severe heat wave with temperatures as high as 49 °C (120 °F).

Our concern now is focusing on predicting the future likelihood of heat waves and their severity. In addition, because in most of the world most of those suffering the impacts of a heat wave will be inside a building, and this will modify the temperatures they are exposed to, there is the need to link climate models to building models. This means producing example time series of future weather. Other work has shown that future mortality due to heat waves could be reduced if buildings were better designed to modify the internal climate, or if the occupants were better educated about the issues, so they can take action in time.

Underreporting and "Harvesting" effect

The number of heat fatalities is likely highly underreported due to a lack of reports and misreports. Part of the mortality observed during a heat wave, however, can be attributed to a so-called "harvesting effect", a term for a short-term forward mortality displacement. It has been observed that for some heat waves, there is a compensatory decrease in overall mortality during the subsequent weeks after a heat wave. Such compensatory reductions in mortality suggest that heat affects especially those so ill that they "would have died in the short term anyway".

Another explanation for underreporting is the social attenuation in most contexts of heat waves as a health risk. As shown by the deadly French heat wave in 2003, heat wave dangers result from the intricate association of natural and social factors.

Psychological and sociological effects

In addition to physical stress, excessive heat causes psychological stress, to a degree which affects performance, and is also associated with an increase in violent crime. High temperatures are associated with increased conflict both at the interpersonal level and at the societal level. In every society, crime rates go up when temperatures go up, particularly violent crimes such as assault, murder, and rape. Furthermore, in politically unstable countries, high temperatures are an aggravating factor that lead toward civil wars.

Additionally, high temperatures have a significant effect on income. A study of counties in the United States found that economic productivity of individual days declines by about 1.7% for each degree Celsius above 15 °C (59 °F).

Power outages

Abnormally hot temperatures can cause electricity demand to increase during the peak summertime hours of 4 to 7 p.m. when air conditioners are straining to overcome the heat. If a hot spell extends to three days or more, however, nighttime temperatures do not cool down, and the thermal mass in homes and buildings retains the heat from previous days. This heat build-up causes air conditioners to turn on earlier and to stay on later in the day. As a result, available electricity supplies are challenged during a higher, wider, peak electricity consumption period.

Heat waves often lead to electricity spikes due to increased air conditioning use, which can create power outages, exacerbating the problem. During the 2006 North American heat wave, thousands of homes and businesses went without power, especially in California. In Los Angeles, electrical transformers failed, leaving thousands without power for as long as five days. The 2009 South Eastern Australia Heat Wave caused the city of Melbourne, Australia to experience some major power disruptions which left over half a million people without power as the heat wave blew transformers and overloaded a power grid.

Wildfires

If a heat wave occurs during a drought, which dries out vegetation, it can contribute to bushfires and wildfires. During the disastrous heat wave that struck Europe in 2003, fires raged through Portugal, destroying over 3,010 square kilometres (1,160 sq mi) or 301,000 hectares (740,000 acres) of forest and 440 square kilometres (170 sq mi) or 44,000 hectares (110,000 acres) of agricultural land and causing an estimated 1 billion worth of damage. High end farmlands have irrigation systems to back up crops with. Heat waves cause wildfires.

Physical damage

Heat waves can and do cause roads and highways to buckle and melt, water lines to burst, and power transformers to detonate, causing fires. See the 2006 North American heat wave article about heat waves causing physical damage.

Heat waves can also damage rail roads, such as buckling and kinking rails, which can lead to slower traffic, delays, and even cancellations of service when rails are too dangerous to traverse by trains. Sun kinking is caused when certain types of rail design like short section rails welded together or fish plate rails expand and push on other sections of rail causing them to warp and kink. Sun kinking can be a serious problem in hotter climates like Southern USA, parts of Canada, the Middle East, etc.

In the 2013 heatwave in England, gritters (normally only seen in snow) were sent out to grit melting tarmac roads.

Global warming

Climate models reveal that future heat waves will have a more intense geographic pattern. Model results show that areas associated with the severe heat waves in Chicago in 1995 and Paris in 2003 will experience more intense, more frequent, and longer-lasting heat waves in the second half of the 21st century. Heat waves today in Europe and North America happen parallel to the conditions of atmospheric circulation. Increased anthropogenic activities causing increased greenhouse gas emissions show that heat waves will be more severe.

Heat waves and droughts as a result, minimize ecosystem carbon uptake. Carbon uptake is also known as carbon sequestration. Extreme heat wave events are predicted to happen with increased global warming, which puts stress on ecosystems. Stress on ecosystems due to future intensified heat waves will reduce biological productivity. This will cause changes in the ecosystem's carbon cycle feedback because there will be less vegetation to hold the carbon from the atmosphere, which will only contribute more to atmospheric warming.

Policy makers, funders and researchers responding to the increasing heatwaves created the Extreme Heat Resilience Alliance coalition under the Atlantic Council to advocate for naming heatwaves, measuring them, and ranking them to build better awareness of their impacts.

Examples

June 2019 was the hottest month on record worldwide, the effects of this were especially prominent in Europe. The effects of climate change have been projected to make heat waves in places such as Europe up to five times more likely to occur. Among other effects, increased wildfires in places such as Spain can also be attributed to heat waves.

In July 2019, over 50 million people in the United States were present in a jurisdiction with any type of heat advisory. Scientists predicted that in the days following the issuance of these warnings, many records for highest low temperatures will be broken: i.e. the lowest temperature in a 24-hour period will be higher than any low temperature measured before.

In addition to posing a threat to human health, heat waves significantly threaten agricultural production. In 2019, heat waves in the Mulanje region of Malawi experienced temperatures as high as 40 °C (104 °F). Heat waves and a late rain season resulted in significant leaf scorching of tea leaves in Malawi, leading to reduced yields.

The 2021 Western North America heat wave resulted in some of the highest temperatures ever recorded in the region, including 49.6 °C (121.3 °F), the highest temperature ever measured in Canada.

 

Memory and trauma

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Memory_and_trauma ...