The Year ' Without a Summer"
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Ships' Logbooks and "The Year ' Without a Summer" , Michael Chenoweth Elkridge, Maryland ABSTRACT Weather data extracted from the logbooks of 227 ships of opportunity are used to document the state of the global climate system in the summer of 1816 ("The Year Without a Summer"). Additional land-based data, some never be- fore used, supplement the marine network. The sources of the data are given and briefly discussed. The main highlights of the global climate system in the 3-year period centered on the summer of 1816 include: • a cold-phase Southern Oscillation (SO) (La Nina) event in the Northern Hemisphere (NH) winter of 1815-16, which was preceded and followed by warm-phase SO (El Nino) events in the winters of 1814/15 and 1816/17; • strong Asian winter and summer monsoons, which featured anomalous cold in much of south and east Asia in the winter of 1815/16 and near- or above-normal rains in much of India in the summer of 1816; • below-normal air temperatures (1°-2°C below 1951-80 normals) in parts of the tropical Atlantic and eastern Pacific (in the Galapagos Islands), which imply below-normal sea surface temperatures in the same areas; • a severe drought in northeast Brazil in 1816-17; • an active and northward-displaced intertropical zone in most areas from Mexico eastward to Africa; • generally colder-than-normal extratropical temperature anomalies in both hemispheres; • an area of anomalous warmth (1°-2°C above 1951-80 normals) in the Atlantic between Greenland and the Azores during at least the spring and summer of 1816; and • an active Atlantic hurricane season in both 1815 and 1816. A general circulation model simulation of the spatial patterns of high latitude NH temperature anomalies in the first winter following a major volcanic eruption (Graf et al. 1993) is not fully supported by the results in the North American sector where warming in Greenland was observed in 1816, as the GCM indicates cooling. The area of maximum cool- ing over North America near 50°N, 90°W in 1816 is north of the GCM results. This second difference may be partly attributed to the effects of the cold-phase SO (La Nina) event superimposed on the volcanic signal. Elsewhere in North America, Asia, and Europe, there is generally good agreement between the observed patterns and the GCM results. 1. Introduction produced a sharp rise in the prices of most agricul- tural commodities, ruined many small farmers, and In the December 1924 issue of the Monthly strained an economy still recovering from the War of Weather Review, W. Milham described the unusual 1812. In the following 70 years since Milham's ar- weather of the year 1816 as probably the most writ- ticle, the events of that summer have been described ten about weather event in American history (Milham in ever-increasing detail in further articles and mono- 1924). Repeated outbreaks of cold weather and a se- graphs (Hoyt 1958; Ludlam 1966; Chenoweth 1985; vere summer drought contributed to crop failures that Wilson 1985a,b; Hamilton 1986, to mention only sources concerned with North America), two books (Post 1977; Stommel and Stommel 1983), and an in- ternational conference in 1988 (Harington 1992). The Corresponding author address: Dr. Michael Chenoweth, 6816 Ducketts Lane, Elkridge, MD 21227. 1988 conference brought together a number of re- In final form 28 February 1996. searchers from different fields of study. From both ©1996 American Meteorological Society direct and proxy records of weather, the first attempt Bulletin of the American Meteorological Society 2025 Unauthenticated | Downloaded 10/05/21 01:32 PM UTC to document the worldwide pattern of weather and journals kept on ships from as far back as the 1830s. climate in 1816 was made. Table 1 lists the archives holding ships' logbooks and Meteorological and oceanographic data from the journals queried or visited by the author. A visit to oceans for the eighteenth and early nineteenth centu- maritime museums in the United States in May 1995 ries are only now beginning to be digitized. The best- revealed the extent of the collections (thousands of known example is the data in the Maury Collection logbooks, many on microfilm), and it was not unusual at the National Archives in Washington, D.C. (J. Elms to be told that I was the first person ever to visit and 1995, personal communication). There are only about use the logbooks for climatological purposes. half a dozen abstracts from ships' logbooks for the Land-based records also form an integral part of the year 1816 in the Maury Collection. Fortunately, the 1816 dataset. Many archives contain land records in the sparsity of the data can be overcome by using the form of weather diaries and journals, correspondence, massive collection of logbooks of the British Royal lighthouse records, traveller accounts, surveying expe- Navy, housed at the Public Record Office in London. ditions, learned journals, almanacs, and local histories. In addition, a search made at other institutions and Newspapers are a very important source. Figure 1 pre- maritime museums has uncovered previously unstud- sents summer temperature data taken from a 23-year ied 1816 weather data. series published monthly in a Nassau, Bahamas, news- This article will briefly discuss the archival sources paper from 1815 to 1837 in the collection of the British and data types used to reconstruct the state of the glo- Library Newspaper Library.1 Most coastal newspapers bal climate system in 1816 and also describe that sys- published shipping news containing accounts of tem. It should be kept in mind that other years are storms and other weather data that have not survived represented in these archival sources and that there are in any other form. Table 2 includes a list of institu- other collections holding marine data that do not cover tions holding land-based records for the 1816 period. the years 1815-17. A more complete treatment of the entire dataset will be the subject of a more compre- hensive work at a future date. 3. Global climate in 1816 The weather data extracted from the ships' log- 2. Data types and data sources books and land records have been gathered, and digi- tization of the data is planned. However, preliminary Historical daily marine data are found largely in analysis offers sufficient information to provide a two primary sources. The most important is the log- coherent picture of the state of the global climate sys- books of ships of opportunity. These form the main tem in the wake of the April 1815 eruption of source of meteorological and oceanographic data. A Tambora. References to marine temperature anoma- second source is passenger or crew journals. These lies are with respect to the Global Ocean Surface Tem- journals often include data normally found in a log- perature Atlas dataset (Bottomley et al. 1990) for the book (position, course, weather) and are a valuable reference period 1951-80. Only limited marine data addition because often the logbook of the ship on outside of the period November 1815-September which the journal was kept is not now extant. 1816 are available, so comparisons with contempo- Logbooks and journals are widely dispersed and rary normals are not possible but are given when avail- can turn up in surprising places. The largest collec- able for land data. tions are normally found in national archives such as the Public Record Office. Regional archives and a. Tropical Pacific and Southern Oscillation (SO) historical societies are important sources of merchant conditions shipping logbooks as well as naval logbooks not Most compilations of historical El Nino events in- present in government collections. These regional clude 1814 (or 1814-15) as an El Nino year (Eguiguren depositories, including maritime museums, also hold logbooks kept by whalers and sealers. Finally, smaller collections of logbooks are held in places such as 1 The mailing address for the British Library Newspaper Library the archives of the Presbyterian Church (USA), is 120 Colindale Avenue, London NW9 5HE, England. The Philadelphia, Pennsylvania, which holds logbooks Nassau Royal Gazette and Bahamas Advertiser are found on dating from the 1880s and 1890s, and missionary microfilm reel M.C. 428. 2030 Vol. 77, No. 9, September 1 996 Unauthenticated | Downloaded 10/05/21 01:32 PM UTC 1894; Quinn et al. 1978; Hamilton and Garcia 1986), and Quinn et al. also give 1817 as a year with a moderate El Nino. Data sources used in this study indicate that late 1815 and the first half of 1816 were characterized by cold- phase Southern Oscillation (La Nina) conditions. The available air temperature data in the Pacific indicate air temperatures av- eraging 1.5°C below 1951-80 averages in the Galapagos Islands in late February and early March 1816 (Hill 1816), and near or below normal in other areas of the Pacific except around Hawaii in April 1816 (Hill 1816; von Kotzebue FIG. 1. Average summer temperature anomaly (°C) at Nassau from 1815 to 1821). Barometric pressure data for 1837. Reference normal: period of record is 1815-37. The cold summers of 1815 Bombay (Bombay Courier 1816a,b), and 1816 are especially impressive, as both years are the two driest (fewest number Calcutta (Jameson 1820), and Madras of days with precipitation) in this early series. If the low rainfall frequencies are 2 correlated with local cloud cover, then this may be taken to be evidence of the (The Royal Society ) indicate below- effect of the volcanic dust veil in lowering the surface air temperature. The entire normal pressure anomalies in the first record may also be considered as a proxy record of local sea surface temperature half of 1816, with a rise to above-normal anomalies near and upwind of the prevailing easterly surface wind flow.