[eccentric]

The most likely cause was volcanic influences. Proponents note that a number of major volcanic eruptions preceded 1816: Soufriére and St. Vincent in 1812: Mayon and Luzon in the Phillippines during 1814; Tambora in Indonesia during 1815. The volcanic theory of climatic influence relates increased volcanic activity with decreased temperatures due to the increased reflection of solar radiation from volcanic dust blown and trapped high in the atmosphere. The Tambora eruption has been estimated to be the most violent in historical times. The explosion is believed to have lifted 150 to 180 cubic kilometres of material into the atmosphere. For a comparison, the infamous 1883 eruption of Krakatau ejected only 20 cubic kilometres of material into the air, and yet it affected sunsets for several years after.

The first thing I thought of was volcanoes, too. But, as I kept reading, there were no mentions of 'blood red' or colorful sunstes as I had read about with Krakatau.

sunspots, maybe?

Thanks for the link to Tambora. I'll have to check that out.

[blam]

"The first thing I thought of was volcanoes, too. But, as I kept reading, there were no mentions of 'blood red' or colorful sunstes as I had read about with Krakatau. "

The special I just watched covered this aspect by showing the red sunsets painted by various artists of that time.

[AntiGuv]

There's really no doubt that Tambora caused the Year Without Summer. If anything, it's a bit odd that this commentary seems so uncertain in attributing it.