but we all understand that human pollution is as bad or worse than the explosion of a supervolcano for super-charging the atmosphere.

The jury is still out on that statement. You also overlook the importance of timescale.
"If yellowstone erupted (or more accurately when)for volcanologists, the biggest worry is prevaiing wind and ash distribution. A circle about 500 miles (800 kilometers) across surrounding Yellowstone might see more than 4 inches (10 centimeters) of ash on the ground, scientists reported( Aug. 27, 2014, in the journal Geochemistry, Geophysics, Geosystems.)

The ash would be pretty devastating for the United States, scientists predict. The fallout would include short-term destruction of Midwest agriculture, and rivers and streams would be clogged .
People living in the Pacific Northwest might also be choking on Yellowstone's fallout.

"People who live upwind from eruptions need to be concerned about the big ones," said Larry Mastin, a USGS volcanologist and lead author of the 2014 ash study. Big eruptions often spawn giant umbrella clouds that push ash upwind across half the continent, Mastin said. These clouds get their name because the broad, flat cloud hovering over the volcano resembles an umbrella. "An umbrella cloud fundamentally changes how ash is distributed," Mastin said."
Yellowstone Volcano's next supereruption is likely to emit vast quantities of gases such as sulfur dioxide, which forms a sulfur aerosol that absorbs sunlight and reflects some of it back to space. The resulting climate cooling could last up to a decade. The temporary climate shift could alter rainfall patterns, and, along with severe frosts, cause widespread crop losses and famine.
These events outlined, although largely conjectural, would have an immediate undeniable impact. The only real question is the extent of the ash, the duration and extent of the impact on climate, That these events would occur is inevitable, the uncertainty is the severity.
Just as well the Snowdonia supervolcano in Wales is extinct.
Krakatoa was a smaller event yet killed up to 130000 people and Average global temperatures fell by as much as 1.2 °C (2.2 °F) in the year following the eruption. Weather patterns continued to be chaotic for years and temperatures did not return to normal until 1888.