Danièle Lavallée

Holocene history of ENSO variance and asymmetry in the eastern tropical Pacific

El Niño shifted between the center and the East El Niño has changed quite a bit over the past 10,000 years. During some periods it was less variable than now, and during others it shifted from its current locale toward the central Pacific. Carré et al. analyzed the shells of mollusks from Peru to construct a record of the El Niño–Southern Oscillation (ENSO) in the eastern Pacific over the Holocene period. They compared this record with other records from the rest of the Pacific to reveal how much the strength and frequency of El Niños changed and how their positions varied. Science, this issue p. 1045 El Niño–Southern Oscillation warming of the sea surface was strongly skewed toward the central Pacific in the Mid-Holocene. Understanding the response of the El Niño–Southern Oscillation (ENSO) to global warming requires quantitative data on ENSO under different climate regimes. Here, we present a reconstruction of ENSO in the eastern tropical Pacific spanning the past 10,000 years derived from oxygen isotopes in fossil mollusk shells from Peru. We found that ENSO variance was close to the modern level in the early Holocene and severely damped ~4000 to 5000 years ago. In addition, ENSO variability was skewed toward cold events along coastal Peru 6700 to 7500 years ago owing to a shift of warm anomalies toward the Central Pacific. The modern ENSO regime was established ~3000 to 4500 years ago. We conclude that ENSO was sensitive to changes in climate boundary conditions during the Holocene, including but not limited to insolation.

Quebrada de los burros: Los primeros pescadores del litoral pacífico en el extremo sur peruano

Resumen es: Las excavaciones en la Quebrada de los Burros, en el litoral de Tacna (Peru), han descubierto un campamento de pescadores y recolectores de moluscos (QlB...