ENSO, sun and megadroughts in SW USA during the last 11,000 years

• Holocene P. edulis pollen stack from Southern Rockies shows similarities with ENSO records. SW USA could be used as a proxy for effective precipitation and variability. increased in the last 6,000 years due to enhanced El Niño conditions. Solar-induced centennial-scale variability controlled past abundance oscillations. Oscillation (ENSO) is one of most important modes climate system. However, instrumental records are too short characterize its natural at long-term timescales. Paleoclimate showing during on centennial millennial timescales rare but critical our understanding multidecadal- millennial-scale Here we several sensitive piñon pine ( Pinus ) Rockies, USA, produce detailed continuous record ENSO-like 11,000 yrs. La Niña conditions dominated Early while an increasing trend over This was modulated by hydrological activity prominent 900-1,000-yr cycles amplitude these until present. Enhanced related multidecadal megadroughts occurred centered ca. 10, 8, 6.8, 5.8, 4.8, 4, 3, 2.2, 1 ka. Insolation solar output changes suggested here main triggers vegetation changes. Our analysis recent strong events, representing modern analogs conditions, indicates anomalously dry persisting annually, leading prolonged drought that impact growth. Following thermostat hypothesis Sun-ENSO link, such expected prevail future, which combined temperatures, will likely generate USA.