I don't know how many volcanoes are erupting around the globe on any given day. It may be 50 or more. I do know that many active volcanoes in my region (Washington and Oregon) seem to be waking up and coming to life in earthquake swarms and ground lift. In the not so distant past (19th Century) volcanoes have caused instant global cooling and crop failures. In the more distant past, eruptions may be connected to mini Ice Ages. Caldera volcanoes like at Yellowstone which erupt every few hundred thousand years have the capacity to basically destroy civilization over an entire continent. It has been thought that tectonic activity and forces related to the core of the Earth were connected to volcanic activity on the surface. More recently there have been suggestions the Sun and the Moon may play a role in tectonics on our planet.