Two centuries ago, the world was in the middle of a climate emergency. It was a mega-disaster that produced three successive years of destructive global cooling and human tragedy.

Tens of millions died, famine and disease swept the world, and governments across Europe feared riots and revolution.

Remarkably, at the time no-one knew what had produced the extreme weather crisis.

It was sparked in 1815 when the 4300 metre-high volcano, Tambora, literally blew its top off. The eruption - on the Indonesia island of Sumbawa - was the largest ever recorded in human history.