All in all, I'm glad that my ancestor emigrated. Tremendous opportunities for his descendants.
One of the big problems was that ireland went to one potato variant, the lumper, which was the easiest to grow. When the blight hit, they no longer had a genetically diverse potato crop. If they did, they probably could have made it through much easier.
We need a better word than famine. It is not a famine when you are exporting food (crops, livestock) from the country affected by the failure of a single crop. The Brits debated about what to do about the "Irish problem" (as if it were a separate country) while the Irish population went from 8M to 4M (1M dead, 3M emigrated).
In the end, the Irish emigration to North America had profound effects on history. Those who went to America found work and helped the country grow, They fought in the Civil War (mostly for the north) and confederate generals after the war said they may have held off the North if they had more Irish troops. So the US may have split in two. After the war, many Irish went west and helped build the trans-continental railroad, which kept the West coast part of the country (Nothing Like it in the World by Ambrose is a great book, BTW). If the US had been 2 or 3 countries at the time of WWI or WWII, would those wars have come to the same conclusion?
Happy St. Pats day