Why do CO2 and SO2 from large eruptions affect climate differently?

Answer: SO2 turns into tiny reflective particles that cool briefly, while CO2 traps heat for much longer.

CO2 is the only gas that matters because sulfur washes out before it can change climate. — Carbon dioxide does stay in the air for a very long time, so it matters for long-term warmth. But sulfur does not disappear before it acts: it quickly forms reflective particles and can cool the surface for a while. The mistake is treating 'sulfur leaves fast' as 'sulfur does not matter.'

Every volcanic gas cools the air because eruption plumes reflect sunlight back into space. — Some volcanic gases do cool the planet, because sulfate particles reflect sunlight. But CO2 does the opposite: it traps heat instead of reflecting it. The error is assuming every gas has the same cooling effect.

SO2 turns into tiny reflective particles that cool briefly, while CO2 traps heat for much longer. ✓ — Right. SO2 reacts in the atmosphere to form sulfate particles that scatter sunlight, so the lower atmosphere cools for a while. CO2 stays in the air much longer and traps outgoing infrared radiation, which warms the climate. So one eruption can cool first and warm later.