The Great Irish Potato Famine occurred during a period of mass starvation, disease and emigration between 1845 and 1850. According to the journal "The Context of Migration: The Example of Ireland in the Nineteenth Century" by James H. Johnson, this resulted in a decrease in the Irish population of 20 to 25% and it did not stabilize again until the 1930s. Although there was a poor potato harvest in Europe in the 1840s, a third of the Irish population depended on the crop. This was inevitable due to the Irish people's sole reliance on home-grown potatoes and the fact that the population nearly doubled between 1800 and 1840. The journal Spaces for Famine: A Comparative Analysis in Ireland and the Highlands in the 1840's" by Liz Young states that "if the crops were bad or poor, families would not be able to get by and, to compare, 50,000 people died when the crops failed in 1817-1819" . The Irish people could not provide for their potato needs because they could not afford to buy more seed or, indeed, buy land on which to grow enough potatoes to feed their families which multiplied rapidly for a year. As family sizes increased, their excess production, which previously would have enabled them to purchase livestock, etc., was consumed. Many factors were involved in this disaster. The main causes were environmental conditions, agricultural practices and climatic conditions, economic faults and social and political trends. Social unrest and the history of Irish poverty were the direct cause of the Irish Potato Famine and the sole reliance on potato farming which inevitably led them to famine . He is mentioned in the journal “The Demographic Factor in the Irish Movement towards Partition (1607). -1921)” ...... middle of paper ......b. 2012. http://www.jstor.org.>• Young, Liz. “Spaces for Famine: A Comparative Geographic Analysis of Famine in Ireland and the Highlands in the 1840s.” Transactions of the Institute of British Geographers 4th ser. 21 (1996): 666-80. JSTOR. Internet. February 25, 2012. • Johnson, James H. “The Context of Migration: The Example of Nineteenth-Century Ireland.” Transactions of the Institute of British Geographers 3rd ser. 15 (1990): 259-76. JSTOR. Internet. February 26, 2012. http://www.jstor.org.>• “Irish Potato Famine.” Encyclopedia Britannica. Online academic edition of the Encyclopædia Britannica. Encyclopædia Britannica Inc., 2012. Web. February 25, 2012. • Fernández-Armesto, Felipe. “Replacing muscle: energy revolutions”. History of the world. Boston: Pearson Prentice Hall, 2010. 5. Principle