By contrast, in 1991 Mount Pinatubo emitted 17 million tons of SO2, and that cooled the globe about 0.4°C from 1991 to 1993.
The NASA article says
The SO2 total is much lower than the recent Holuhraun eruption [August 29, 2014], which released about 11–12 [million tons], or 30 to 40 times more than Calbuco. “But the SO2 from Holuhraun was emitted over several months and was mostly confined to the lower troposphere, limiting its climate impacts,” [Simon] Carn noted. “In terms of climate impacts, Calbuco is probably more significant due to the stratospheric SO2 injection.”So unless there are more massive eruptions in its near future, Calbuco doens't look likely to impact global temperatures. But
“Although a single eruption of this size is unlikely to have a measurable effect on climate,” Carn added, “recent work suggests that the cumulative effects of multiple volcanic eruptions of this size in the past decade may have slowed the rate of global warming due to the stratospheric sulfate aerosols produced.”