It happened in the 90s when Pinatubo blew. Scientists are coming to a consensus that an active Icelandic volcanic chain is entering its high-activity phase and eruptions and ash clouds could last for decades. If these ash clouds rise high enough and have enough reflective sulfurous material, than can slow the runaway warming. Lucky break for us humans in terms of the timing. We already got a solar minimum the last couple of years. Hubs for air travel may shift west - Nantes, Madrid, and Bordeaux anyone?