The Great Irish Potato Blight Of 1845

Ireland has a damp, maritime climate due to its proximity near the eastern edge of the Atlantic Ocean. This cool, damp climate helps to favor the growth of the potato, but is also ideal for the spread of blight. The blight caused by the water mold, Phytophthora infestans (P. infestans), tends to thrive in these conditions, where it develops spores on the leave and washes into the rain-soaked soil to affect the growing roots.  The summer of 1845 was especially wet. By this time, a zonal flow pattern had emerged, which can deepen the Rossby Waves (large-scale waves associated with the polar jet stream separating the cold polar air from warm tropical air) and can act as a blocking system for up to 10 weeks at a time. This can affect entire growing seasons and prolong excessive wet, dry, or cold conditions.  Sea surface temperatures were above normal for most of the period, but it is unclear how an ENSO event affects Ireland and northern Europe. It is thought that a moderate El Niño may lead to a slightly colder, wetter winter, but that is also dependent on NAO (North Atlantic Oscillation).

Not only did climate play a huge impact in the role of the blight, but certain impacts such as poverty, economics, and politics also played a factor. The weather was also rough in England and poor Irish farmers shipped what they had to England, leaving their own families with barely enough to eat. Trade from the North America introduced new diseases and mutations (including this specific strain of potato blight). This certain potato was only one of two of its kind- an increase in genetic variety may yield a better crop. In the early stages of the famine, the British government also wasn’t prepared to deal with the magnitude of the crisis, and thus, were slow to react.

Weather affects the severity of many plant diseases, but climate change is likely to alter the patterns of disease severity in crops. With a changing climate, areas that are warm may get even warmer causing crops to wilt ; dry areas may be more susceptible to prolonged drought, meaning a less predictable harvest from year to year. In the future, drought, extreme heat, and widespread flooding events will complicate farming in Asia, sub-Saharan Africa, and Latin America. Already, we are seeing the effects of climate on Mexican farmers and wilting crops. Evaluating future patterns can help to focus crop breeding to produce more resilient plants and focus on disease management research. While the strain that caused the potato blight is still a common potato disease and gives us an idea of what famine may look like in the future, the focus must shift toward constantly improving technology to prepare for warming and other various impacts.

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© 2018 Meteorologist Sharon Sullivan