The summer of 1816 was so cold that crops failed to ripen. Tens of thousands of people died of starvation in various parts of Europe in the following year or so. The cold weather affected the US as well but I don’t think there was widespread starvation—more sources of food and a sparser population.
was the 1816 freeze caused by the Icelandic volcano?
The Little Ice Age brought colder winters to parts of Europe and North America. Farms and villages in the Swiss Alps were destroyed by encroaching glaciers during the mid-seventeenth century. Canals and rivers in Great Britain and the Netherlands were frequently frozen deeply enough to support ice skating and winter festivals. The first River Thames frost fair was in 1607 and the last in 1814; changes to the bridges and the addition of an embankment affected the river flow and depth, hence diminishing the possibility of freezes. Freezing of the Golden Horn and the southern section of the Bosphorus took place in 1622. In 1658, a Swedish army marched across the Great Belt to Denmark to attack Copenhagen. The winter of 1794-1795 was particularly harsh, when the French invasion army under Pichegru could march on the frozen rivers of the Netherlands, while the Dutch fleet was fixed in the ice in Den Helder harbour. In the winter of 1780, New York Harbor froze, allowing people to walk from Manhattan to Staten Island. Sea ice surrounding Iceland extended for miles in every direction, closing harbors to shipping.
The population of Iceland fell by half, but this was perhaps caused by fluorosis after the eruption of the volcano Laki in 1783. Iceland also suffered failures of cereal crops, and people moved away from a grain-based diet. The Norse colonies in Greenland starved and vanished (by the early fifteenth century), as crops failed and livestock could not be maintained through increasingly harsh winters, though Jared Diamond noted they had exceeded the agricultural carrying capacity before then. In North America, American Aborigines formed leagues in response to food shortages. In Lisbon, Portugal, snowstorms were much more frequent than today. Heavy snowfalls in the winters of 1665, 1744 and 1886 were reported.
Throughout the Little Ice Age, the world experienced heightened volcanic activity. When a volcano erupts, its ash reaches high into the atmosphere and can spread to cover the whole earth. This ash cloud blocks out some of the incoming solar radiation, leading to worldwide cooling that can last up to two years after an eruption. Also emitted by eruptions is sulfur in the form of sulfur dioxide gas. When this gas reaches the stratosphere, it turns into sulfuric acid particles, which reflect the sun's rays, further reducing the amount of radiation reaching Earth's surface. The 1815 eruption of Tambora in Indonesia blanketed the atmosphere with ash; the following year, 1816, came to be known as the Year Without a Summer, when frost and snow were reported in June and July in both New England and Northern Europe. Other volcanoes that erupted during the era and may have contributed to the cooling include Billy Mitchell (ca. 1580), Mount Parker (1641), Long Island (Papua New Guinea) (ca. 1660), Laki (1783) and Huaynaputina (1600)
I dunno about starvation, but I do know that notably Thomas Jefferson had crop failures which plunged him into debt. If you look at newspapers from that period, they were (obviously) really confused. The scientific speculation was quite interesting. Sunspots were one of the supposed causes.