“The magma chamber under volcano Hekla is now almost full, according to Páll Einarsson, professor in geophysics at University of Iceland.
Hekla, which is the most active volcano in Iceland, could erupt with very short notice, Páll told Morgunblaðið, adding that people should not climb the mountain.
During the last eruption, in 2000, it took just 79 minutes from the first quake until eruption, and Páll says that was longer than in previous eruptions.
Hekla has erupted more than 20 times in the last 1,000 years. The last big eruption in Hekla was in 1947.”
http://icelandreview.com/news/2014/03/17/hekla-volcano-could-erupt-soon
The problem with Hekla is that it is a northern hemisphere volcano, and any significant eruption of material into the atmosphere would add more cooling.
In 1104 AD and 1100 BC and 2300 BC and 4110 BC and 6150 BC Hekla erupted with a VEI of 5. There have been numerous 3s and 4s as well.
A VEI5 is considered “very large” Mount Vesuvius and Mount St. Helens (1980) were VEI5.
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sunshine hours 
I was just thinking, what with all the rain the south of the UK has had in the preceding winter months, if that had fallen as snow – like it did in winter 47 – we’d still be digging out people and animals now and until May/June.
From 1945 to to 1980 there was a pause in the warming that had occurred from 1910 to 1944. I suspect our pause is 15 years into another 35 year period similar to 1945 to 1980. Cold winters are still really possible. 1978/79 was the coldest US winter ever.