Major volcanic eruptions episodically disrupted the continuity of polar warming through aerosol forcing

The polar regions are warming rapidly, exceeding the global average due to greenhouse gas emissions from human activities. Using CMIP6 simulations, HadCRUT5 data, and MERRA-2 aerosol records, this study shows that major 20th-century volcanic eruptions, Agung (1963), El Chichón (1982), and Pinatubo (1991) temporarily offset polar warming through sulfate-induced cooling. The Agung eruption suppressed Arctic surface air temperature anomalies for approximately 4-5 years (1964-1968), El Chichón for a similar duration (1983-1987), and Pinatubo for about 4-5 years (1992-1996), demonstrating a consistent multi-year cooling response following each event. Without these eruptions, Arctic surface air temperature anomalies would have increased by up to 0.5 °C, whereas volcanic activity caused short-term cooling ranging from -0.07 °C to -0.4 °C. Arctic minimum temperatures ( $T_{\min }$ ) are rising faster than maximum temperatures ( $T_{\max }$ ), indicating asymmetric warming. In contrast, Antarctic responses were weaker, moderated by oceanic and atmospheric dynamics. Collectively, these eruptions produced episodic multi-year cooling that temporarily interrupted the ongoing Arctic warming trajectory, with warming resuming as volcanic aerosol forcing diminished. Spatial patterns reveal pronounced warming in the central Arctic, Greenland, and Siberia in the absence of volcanic forcing, highlighting the role of eruptions in modulating polar warming and providing insights relevant to future geoengineering considerations.