It looks like an Alaskan volcano, erupting in 1783 had a permanent impact on — of all things — rainfall over the Nile River.
The volcano produced aerosols which lowered the temperature of the entire Northern Hemisphere by three degrees (C), weakening the African & Indian monsoon by reducing the temperature gradient between land & oceans. As well as reduced tree growth in Alaska, it also substantially reduced tree growth in Sibera.
The cooling led, oddly enough, to unsual warming; so the reduced monsoonal rainfall evapourated faster, forming less runoff. Or in other words, less Nile.
Since the Nile runs for well over 6,000km it had ample opportunity to be effected. This led to record low river levels across not just the Nile, but the entire Sahel region of Africa, including the Niger River.
I was impressed to note activity in one of the coldest, iciest places in the world having a massive effect in one of the hottest, driest places. I’m wondering what might have an impact on Australia’s weather. Cruzeiro do Sul erupts, Australia gets rain?