Croll James 182190

JAMES CROLL WAS a 19th-century Scottish scientist who developed a theory of climate change based on variations in the Earth's orbit. Croll was the leading proponent of an astronomical theory of climate change during the 19th century. Taking into account the precession of the equinoxes, variations in the eccentricity of the orbit, and tilt of the axis, Croll proposed that climate change must be the result of the relation of the Earth to the Sun.

He further speculated, "geological and cosmi-cal phenomena are physically related by a bond of causation." Although his theory has often been criticized, it influenced the work of Serbian geo-physicist Milutin Milankovic and provided important insights into the interplay of astronomical and geological elements.

James Croll was the second son of David Croll, a stonemason, and Janet Ellis. He was born in the village of Little Whitefield, Perthshire, Scotland, on January 2, 1821. He grew up on a farm and received almost no formal education. However, Croll was attracted to philosophy and science from an early age and began to read widely in those subjects. He initially preferred those two disciplines to geology. Croll held a variety of odd jobs, including tea merchant, innkeeper, insurance salesman, and caretaker at the Andersonian College and Museum in Glasgow. All these jobs allowed Croll to read and write about his favorite subjects. His first book, Philosophy of Theism, was published in 1857, at the age of 36. This was followed by a number of scientific publications on electricity, heat, and most importantly, on astronomical controls on geological climate.

His paper, "On the Physical Cause of the Change of Climate During Geological Epochs," published in Philosophical Magazine in 1864, provoked the interest of leading scientists in Scotland and England. In this paper, Croll introduced changes in the Earth's orbital elements as periodic and extraterrestrial mechanisms responsible for the beginning of multiple glacial epochs. Croll argued that the eccentricity of the Earth's orbit was sufficiently great to explain every extreme of climatic change evidenced by geology. His theory of ice ages was built on the precession of the equinoxes and variations in the shape of the Earth's orbit. It forecast that one of the two hemispheres would experience an ice age whenever two conditions occur simultaneously: a markedly elongate orbit, and a winter solstice that occurs far from the Sun.

fellow of the royal society

In 1867, Croll accepted a job in Edinburgh with the Scottish Geological Survey as secretary and accountant. This employment came "more by accident than by choice," as Croll himself admitted. Croll's tasks included ordering, printing, coloring, and selling maps and keeping the accounts and stores in order. The director, Archibald Geikie, encouraged Croll to carry out his own research. In addition to his work on orbital theory, Croll made field excursions on glacial deposits and discovered a pre-glacial riverbed running from Edinburgh to Glasgow. Although in later life he suffered from severe headaches that limited his intellectual work, he still produced numerous papers on climate change, glacier motion, geological time, ocean currents, and astrophysics.

In 1875, Croll published his major book, Climate and Time, a work that his ill-health delayed by several years, but that, once published, was widely admired. The publication of this book led to his election as a Fellow of the Royal Society. The University of St. Andrews also awarded him an honorary degree. He was invited to lecture at the Royal Institution, but turned down the invitation due to ill-health and his reserved character.

He rarely attended the meetings of the British Society for the Advancement of Science. By 1871, Croll was growing increasingly dissatisfied with geological subjects and wanted to devote most of his time to the study of philosophy. In 1880, Croll retired from the Survey, expecting a full pension because of his advanced age. He was only given credit for 13 years of employment and saw his income drop dramatically. Because of this precari ous financial situation, Croll was forced to give up housekeeping and go into rented lodgings.

During his retirement, Croll wrote two more scientific books: Discussions on Climate and Cosmology (1886), and Stellar Evolution and its Relations to Geologic Time (1889). The former was largely a reply to his critics and further developed his theory of the secular change of the Earth's climate.

His health increasingly deteriorating, Croll returned to his first love, philosophy, and saw the publication of his fifth book, The Philosophical Basis of Evolution (1890), a response to Darwinism and Spencerianism, in the year of his death. He died on December 15, 1890.

The astronomical theory of climate change emerged 1864-90 thanks to the work of James Croll. However, because of uncertainties in the timing of ice ages and in the stratigraphic record, and because Croll's theory envisaged glaciation in only one hemisphere, the theory was criticized and largely dismissed for at least three decades.

The astronomical theory reemerged from obscurity, thanks to the work of Milutin Milankovic, who reformulated it into a mathematical theory 192041. Even in the case of Milankovic's theory, consensus was far from unanimous because of thermal lags in the climate system and, in part, because of the unexplained lack of continental glaciation prior to the Pleistocene.

However, in 1976, the paleostratigraphic work of James Hayes, John Imbrie, Nicholas Shackelton, and others who documented the astronomical signals in a number of independent proxy climate records confirmed the theory.

SEE ALSO: Earth's Climate History; Ice Ages; Orbital Parameters, Eccentricity; Orbital Parameters, Obliquity; Orbital Parameters, Precession.

BIBLIOGRApHY. J.R. Fleming, "James Croll in Context: The Encounter Between Climate Dynamics and Geology in the Second Half of the Nineteenth Century," History of Meteorology (v.3, 2006); J.C. Irons, Autobiographical Sketch of James Croll: With Memoir of His Life and Work (Kessinger Publishing, 2007).

LUCA PRONO University of Nottingham

Cuba located in the Caribbean, the Republic of Cuba has a land area of 42,803 sq. mi. (110,861 sq. km.), with a population of 11,382,820 (2006 est.), and a population density of 102 people per sq. mi. (264 people per sq. km.). Traditionally, the Cuban economy has been closely tied to the tobacco and sugar industries (the latter still accounts for nearly half of the country's exports).

A total of 24 percent of Cuba is arable land, with a further 27 percent of the country devoted to meadows and pasture. Approximately 94.6 percent of electricity production comes from fossil fuels, mostly petrol sourced from Venezuela. Hydropower is responsible for only 0.4 percent of all electricity. Although there is low automobile use in Cuba, many of the automobiles in the country are older models with heavy fuel consumption, and many still use lead-based gasoline.

For this reason, the vast majority of the carbon dioxide emissions from Cuba (96 percent) are from the use of liquid fuels, while most of the remainder come from the manufacture of cement. By sector, electricity and heat production account for 39 percent of carbon dioxide emissions, with manufacturing and construction making up nearly 40 percent of the emissions, and transport only 7 percent, with residential use some 3 percent. About 24 percent of the country is forested, with much mahogany used for export, and cedar turned into cigar boxes.

Global warming and climate change have had the effect of raising the temperature of the waters in the Caribbean, and it seems likely that this trend will continue, along with higher average temperatures. These higher water temperatures are already having a detrimental effect on the fish in the Caribbean Sea, affecting the local fishing industry, which is the third most important industry in the country, after sugar and nickel.

The Cuban government ratified the Vienna Convention in 1992, and took part in the United Nations Framework Convention on Climate Change signed in Rio de Janeiro in May 1992. It signed the Kyoto Protocol to the UN Framework Convention on Climate Change on March 15, 1999, and ratified it on April 30, 2002, with it taking effect on February 16, 2005.

See ALSO: Alternative Energy, Ethanol; Automobiles; Oceanic Changes; Venezuela.

Rising water temperatures in the Caribbean Sea are affecting Cuba's fishing industry—its third most important industry.

BIBLIOGRApHY. "Cuban Global Warming Alert," Dominican Republic One (July 12, 2007); Neftali Garcia-Martinez, Tania Garcia-Ramos, and Ana Rivera-Rivera, "Seeking Agricultural Sustainability: Cuban and Dominican Strategies," in S.L. Baver and B.D. Lynch, eds., Beyond Sun and Sand: Caribbean Environmentalisms (Rutgers Uni-veristy Press, 2006); Gillian Gunn, Balancing Economic Efficiency, Social Concerns and Political Control (Georgetown Univeristy Press, 1994); J.L. Rodriguez, "The Cuban Economy in a Changing International Environment," Cuban Studies (v.23, 1993); World Resources Institute, "Cuba—Climate and Atmosphere," www.earthtrends.wri. org (cited October 2007).


Geelong Grammar School, Australia

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