claim: However, volcanoes have had very little impact on the last 40 years of global warming.
evidence: The Younger Dryas (around 12,800 to 11,550 years BP) was a return to glacial conditions after the Late Glacial Interstadial, which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM) started receding around 20,000 BP.