Recently I came across the potato famine and how it contributed or even caused the revolutions of 1848. I wondered if this is an good example to show how cascading failures lead from an natural event to an agricultural crisis, to an economic crisis, to an financial crisis and finally resulting in a political crisis.
So what happened?
In the 19th century potatoes became a staple crop in Europe, because they were easy to plant and harvest, cheap and filled you up quite nicely. However, there were very few varieties at that time and this made them vulnerable to disease. In 1845 a new potato disease spread all over Europe and destroyed much of the yearly harvest. This was especially a problem in Ireland (because they almost exclusively used potatoes), but most parts of Central Europe were at least a bit affected. This basically left Europe without potatoes until new varieties could be developed.
In 1846 bad weather also affected the wheat and rye harvest. This lead to rising prices all over Central Europe, as now all major food crops had considerably lower yields. These food shortages forced people to kill most of their livestock, as they did not have any feed for it. But as many people slaughtered their animals at the same time, prices for meat plummeted (though they were still way to high for poor people).
This agricultural crisis lead to an economic crisis, as everybody had to use most of their money for food. Therefore, there wasn’t anything left to buy other consumer goods. This in turn increased unemployment considerably, as many people in the consumer goods industry lost their jobs. Especially in cities this was a problem, as many people had moved their in the last decades and could not find any jobs to sustain themselves.
So, after the agricultural crisis in 1845 and 1846 were followed with an economic crisis in 1846 and 1847, next came an financial crisis in 1847. The financial crisis was mainly driven by the bursting of a bubble around building railroads. In the 1830s and 1840s many railroad projects were started, but most were crap. The bubble burst in 1847 after states started to rise interest rates to consolidate their finances in the economic crisis. In addition, the food crisis diverted funds away from the railroads and this showed that most of the projects could only continue if they got more money continuously. When this did not happen they crashed and with them everyone who had invested their money. This again led to more unemployment as all the railroad companies closed and due to a lack of available loans many smaller businesses went bankrupt, making even more people lose their job.
So in 1848 you had a crashed economy, a debt crisis, still some famine and massive unemployment. Many people all over Europe faces several years of fear, hardship and poverty. They looked for someone to blame. This brought many people to politics. And finally in 1848 we can see revolutions in most states of Central Europe. Some being successful (France), while others failed (Germany). Still, it seems like an new potato disease basically started a chain of events that led to a drastic change of the political landscape in Central Europe.