Campi Flegrei the volcano under Naples italy has been rumbling for a year and in recent months has increased dramatically. The bradyseism (uplift) is increasing and there have been multiple 3.0-4.0+ earthquakes this week along with hundreds of smaller earthquakes. If you remember the Tonga eruption and how that affected the weather, just imagine what will happen when a volcano 50-100 times stronger goes off.
Recently scientist found a weak spot 2 km down inside the Caldera, which is possibly the eruption site. This volcano shows no signs of slowing down if this erupt it will kill half the population due to famine and cold weather.