I assume you refer to the Irish potato famine in the 1840s? If not, please correct me. I’m no historian, so I might miss out some details.
The Irish potato famine (also called the Great Irish famine) was thought to have occurred because of various socio-economic reasons. All of Ireland was part of the British Empire at that time and the Irish-Catholic population (~80% of people living in Ireland) had very few rights. For example, they were not allowed to obtain education (i.e. go to school) nor were they allowed to own land. Instead, most of them rented land to farm and grow crops (barley, wheat, potato). Most of these crops were sold for money to pay the rent for the land, while the potatoes were actually eaten by the farmers.
Now, potato blight is a disease caused by a fungus-like organism (an oomycete called Phytophthora infestans). This pest had been around for as long as potatoes were farmed. But in the 1840s, new and more aggressive strains of this oomycete arrived in Europe (probably originating in the US) and rapidly spread. It caused the loss of entire potato harvests.
The Irish farmers were now faced with a difficult question: they can eat the other crops they’ve produced (wheat and barley), but then they cannot pay the rent for the land and be evicted. Or do they sell their wheat and barley and hope for a better potato harvest the next year? Most tried the second solution, but the new strains of Phytophthora infestans kept destroying their potato crops year after year. Eventually many could not keep up the payments for the land they were renting and were evicted: without a job, they couldn’t buy any other food. A great many people starved to death in those years. The lucky ones could get a passage on ships out of Ireland (mostly to the US).
It’s a dark chapter in our history caused by a combination of events.
I hope that answers your question.
cheers
nikolai
Just to add to Nikolai’s comments; the blight is also advantaged by wet conditions. The Potato Famine coincides with increased wet conditions in Ireland that are associated with what is known as the tail end of the Little Ice Age. It as a period of cooler wetter conditions that exhibited itself slightly differently in different areas across the North Atlantic region. In Greenland, for instance, it almost certainly caused the Norse in Greenland to either leave Greenland altogether because of agricultural or trading failures or to die out. There is still much mystery around this event. In Ireland, before this wetter, cooler period, many small holders expanded onto areas of poor marginal land, partially because of the socio-economic reasons Nikolai describes. Marginal land, however, is more liable to water logging and less fertile for growing crops, so may have also have made crops more susceptible to blight. Across the Irish landscape you can see these former field systems all across the landscape (as rig and furrow marks, which are like linear bumps across the landscape) as people expanded cultivation areas to feed growing populations. Famine was not an un-known event within Ireland previously to the Famine period, but it was the way that the landlords and governments at the time reacted that made what was already a bad situation far worse. The Famine period also coincides with narrow tree ring events within the Irish dendrochronological record, these are usually interpreted as being ‘bad years’ for trees, therefore most likely bad years for crops.
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Nicki commented on :
Just to add to Nikolai’s comments; the blight is also advantaged by wet conditions. The Potato Famine coincides with increased wet conditions in Ireland that are associated with what is known as the tail end of the Little Ice Age. It as a period of cooler wetter conditions that exhibited itself slightly differently in different areas across the North Atlantic region. In Greenland, for instance, it almost certainly caused the Norse in Greenland to either leave Greenland altogether because of agricultural or trading failures or to die out. There is still much mystery around this event. In Ireland, before this wetter, cooler period, many small holders expanded onto areas of poor marginal land, partially because of the socio-economic reasons Nikolai describes. Marginal land, however, is more liable to water logging and less fertile for growing crops, so may have also have made crops more susceptible to blight. Across the Irish landscape you can see these former field systems all across the landscape (as rig and furrow marks, which are like linear bumps across the landscape) as people expanded cultivation areas to feed growing populations. Famine was not an un-known event within Ireland previously to the Famine period, but it was the way that the landlords and governments at the time reacted that made what was already a bad situation far worse. The Famine period also coincides with narrow tree ring events within the Irish dendrochronological record, these are usually interpreted as being ‘bad years’ for trees, therefore most likely bad years for crops.