The famine came at the end of a series of disasters that struck Ireland in the lead-up to the famine.
There had been a series of partial failures of the potato crops and a massive hurricane in the years leading up to the famine.
the very wet weather at the time made it almost impossible to harvest turf for fuel leading to fuel shortage too.
en.wikipedia.org
During the first year of the famine, the British government had provided some very useful famine relief.
The following year was dry and they were no blight leading to a report in Britain that the famine was over. The dry weather result in a much smaller potato crop.
They decided that famine relief would be provided by the poor law to be paid for by Irish ratepayers, not the British government.
en.wikipedia.org
Part of the problem was communication. Reports of how bad the famine in Ireland were not believed in Britain.
They could have provided more relief, but that would have resulted in having to feed millions of Irish at public expense for the indefinite future.
That could be very expensive. The British looked for someone to blame for the problem and decided that Irish landlords created the problem so they should pay for the relief. Many of them were already close to being bankrupt already.
A chemical to stop blight was not discovered until 1882.
en.wikipedia.org
Long-term Irish tenant farms had been made very small due to inheritance rules for Catholics under the penal laws that they had become unviable.
A longer-term solution would have been needed to pay for large-scale emigration to reduce the number of people in Ireland dependent on farming.
Hmm, if we want to go prior to when the Famine occurred, and considering as well (as least as for those of us on the other side of the Atlantic are concerned) that events that happened in Ireland were rarely confined to just Ireland and/or the British Empire (cf. transportation to Australia), I'm just wondering a few things. If Britain was not so condescending about Newfoundland as more than just a seasonal fishing settlement that was begrudingly allowed to turn into a year-round settlement, it and Lower Canada (> Canada East > Quebec) could have become early on as "safety valves" for Ireland, at least population-wise, in order to mitigate the impact of those disasters pre-Famine (hence allowing for more survival of Irish if there's a solid linguistic base outside of Ireland). Climate-wise, both Newfoundland and Lower Canada/Quebec are not Ireland by any means (with Newfoundland basically an island extension of the Appalachian Mountains and much of North America this far north on the wrong side of the Gulf Stream), but something like Newfoundland in particular could be somewhat survivable if the techniques learned by the inhabitants of the Aran Islands are used for more than just root vegetables.
Newfoundland, after all, used to have its own dialect of Irish (spoken primarily on the Avalon Peninsula, in the SE of the island) and during the Famine and after a ticket to what was then called British North America was cheaper than a ticket to the United States. Furthermore, once permanent settlement was allowed legally, a majority of the new settlers were from southwestern England and - more importantly for our purposes - from southeastern Ireland. In part that explains how Irish came to Newfoundland and how the language somehow persisted until it couldn't - as well as British legislation at the time basically encouraging emigration to Newfoundland as prior to the 1820s Newfoundland was not treated as a colony but as a fishery, as well as Irish people being recruited early on in the early stages of English colonization (amidst disputes with the French) for the Grand Banks fisheries. (Indeed, Newfoundland is one of the few places that has its own dedicated name in both Irish and Scottish Gaelic [cf. Nova Scotia], as the Land of Fish/
Talamh an Éisc, reflecting the importance of the fisheries to the island's economy.) So there's one route to get out from under things happening in Ireland at that time, if migration to Newfoundland became more well-established that it would be seen as another extension of Ireland, but with more French speakers (primarily Acadian refugees from ethnic cleansing and French fishermen) and additional people whose ancestry was from southwestern England and whom (even with sectarianism) people would have to learn to get along with.
As for Lower Canada - well, if it was just events happening there alone, there's plenty the British could have done to avoid having the Patriote rebellion in the 1830s from exploding, even with the existing mindset of the times, and thus make the colony more accountable to its people. But, more importantly, prior to the late 1830s French-Canadian nationalism was in its "liberal, inclusive" phase, where while Catholicism was still a presence east of the Ottawa River, it was not really considered an important part to the population - but the Church could be used to bridge the gaps between the two population groups and introduce the Irish to life in Canada, as Canadian nationalism at this point was tolerant of anyone willing to come and partake of its ways. As a result, similar to OTL (but not like it, which was mainly Famine-induced and
with all sorts of horrors) the cold reaches of the Canadian Shield along the Saint Lawrence could have been yet another safety valve (with or without Newfoundland as a stopping point) for the Irish, both seasonal and permanent (in which case, the latter would become included as Canadiens). Even with the presence of indigenous peoples, there's still plenty of space for the Irish to spread out or cluster around in certain areas.
If the networks that were established by immigration abroad happened earlier (and if migration was normalized early on before the Famine, much like the seasonal migrations to Newfoundland to help with the fisheries) as a way of mitigating the impacts of disaster at home, that would have made a difference in handling the Famine better - with, of course, all sorts of consequences for British North America, and not just in the popular mind as de facto additional provinces of Ireland.