I agree modeller....a classic example of volcano effect was Krakatoa - warming mid 19tC was suddenly curtailed by the effects of the volcano - as illustrated by the first Christmas card scenes showing the Thames freezing over and people skating in London on it- never mind the climate data collected by the avid Victorian.
Krakatoa was only a medium-large sized volcano - it is thought that the major volcanoes could trigger ice-ages as their "blanket effect" is so severe that they can trigger a major set-back - the next one due up is the Yellowstone Caldera that, when it last went up, covered an area from current Chicago to Houston with ash, west of the Rockies. The goods news, not for another 250 to 300k years, even though the caulderon is 2/3rds full.
There are, as modeller says, many short, medium and long term factors in play. The consensus of glaciologists is that we are on the slow slide back into another cold recession.