The rumbling Alaskan volcano Redoubt has exploded producing a stratosphere-reaching plume in excess of 60,000 ft (17 km). An eruption is termed ‘ultraplinian’ if its ejecta reaches the stratosphere, about 10km in height. Dust and gases in the stratosphere are known to depress the global temperature for up to a few years after the eruption. The extent of cooling depends on the amount and type of material, the size and duration of ultraplinian eruption, and the latitude (high latitude eruptions like Redoubt are less effective than lower ones).
The plume could be seen easily on infrared here (top center of first radar).