Abstract
Understanding how El Niño-Southern Oscillation (ENSO) responds to
natural variability is of key importance for future climate projections
under a warming climate. However, there is no clear consensus on what
drives ENSO’s variability on centennial timescales. Here, we find that
the epikarst in southeastern Alaska is effective at filtering ENSO and
solar irradiance signals from the Aleutian Low regional climate, which
are subsequently recorded in the speleothem proxy data. By applying a
correlation test, we find that ENSO was significantly influenced by
solar irradiance over the past ~3,500 years. This
relationship dissolved after ~1970 CE, with ENSO now
being dominated by anthropogenic forcing. This implies a new ENSO mean
state that will need to be incorporated into future climate projections.