@article{fdi:010089551,
  title = {{L}ast deglacial environmental change in the {T}ropical {S}outh {P}acific from {T}ahiti {C}orals},
  author = {{K}nebel, {O}. and {F}elis, {T}. and {A}sami, {R}. and {D}eschamps, {P}ierre and {K}oelling, {M}. and {S}cholz, {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{O}n glacial-interglacial time scales, changes in the {E}arth's orbital configuration control climate seasonality and mean conditions. {T}ropical coral skeletons can be sampled at a sufficient resolution to reconstruct past seasonality. {H}ere, last deglacial {P}orites skeletons from {I}ntegrated {O}cean {D}rilling {P}rogram {E}xpedition 310 to {T}ahiti are investigated and, supported by a modern calibration, monthly resolved time series in geochemical proxies ({S}r/{C}a, delta 18{O}, delta 13{C}) are constructed. {F}or most of the deglaciation, {S}r/{C}a seasonality was similar to modern (0.139 +/- 0.010 mmol mol-1; 2.8 +/- 0.2 degrees {C}) reflecting the small change in insolation seasonality. {H}owever, during the {Y}ounger {D}ryas, high values in {S}r/{C}a seasonality (0.171 +/- 0.017 mmol mol-1; 3.4 +/- 0.3 degrees {C}) suggest a reduced mixed layer depth and enhanced influence of the {S}outh {P}acific {S}ubtropical {G}yre due to {S}outh {P}acific {C}onvergence {Z}one ({SPCZ}) inactivity. {F}urthermore, high amplitudes in {Y}ounger {D}ryas skeletal delta 18{O} (0.40 +/- 0.22 parts per thousand) and delta 13{C} (0.86 +/- 0.22 parts per thousand) seasonality compared to modern (delta 18{O} = 0.29 +/- 0.08 parts per thousand; delta 13{C} = 0.27 +/- 0.08 parts per thousand) point to elevated winter-summer discrepancies in rainfall and runoff. {M}ean coral {S}r/{C}a variability suggests an influence of {N}orthern {H}emisphere climate events, such as the {Y}ounger {D}ryas cooling (+0.134 +/- 0.012 mmol mol-1;-2.6 +/- 0.2 degrees {C}), or the {B}olling-{A}llerod warming (+0.032 +/- 0.040 mmol mol-1; -0.6 +/- 0.4 degrees {C}). {D}eglacial mean coral {D}elta delta 18{O} (delta 18{O}seawater contribution to skeletal delta 18{O}), corrected for the ice volume effect, was elevated pointing to more saline, thus dryer conditions, likely due to a northward migration of the {SPCZ}. {S}easonal cycles in coral delta 13{C} were likely caused by variations in linear extension rates that were reduced during the last deglaciation (1.00 +/- 0.6 cm year-1) compared to today (1.6 +/- 0.3 cm year-1). {C}hanges in the {E}arth's movement around the sun are the primary cause of changes in the annual cycle and annual mean of environmental conditions during the last glacial-interglacial periods. {D}istinct from most climate archives, the annual bands of coral skeletons can be sampled at a monthly resolution that allows for reconstructions of past seasonal cycles. {I}n this study, the chemical composition of coral skeletons from the genus {P}orites that grew during the last deglaciation at {T}ahiti (similar to 15,000-9,000 years ago) was analyzed to infer seasonal variations and mean conditions in past sea surface temperature and salinity. {P}rior to application, the methods were successfully calibrated using modern coral skeletons from {T}ahiti. {R}esults showed that sea surface temperature seasonality was similar to today during most of the deglaciation. {H}owever, for the {Y}ounger {D}ryas, a particular cold interval, a marked increase in sea surface temperature seasonality suggests that {T}ahiti was at that time located outside the {S}outh {P}acific {C}onvergence {Z}one, a rain band extending across the tropical {S}outhwest {P}acific. {F}urthermore, coral reconstructions revealed that, although distant, {N}orth {A}tlantic last deglacial climate events influenced mean climate conditions at {T}ahiti. {I}n addition, we show that last-deglacial coral growth rates were reduced compared to today. {L}ast deglacial changes in {T}ahiti coral {S}r/{C}a suggest an influence of {N}orthern-{H}emisphere climate events on the tropical {S}outh {P}acific {V}ariations in last deglacial {T}ahitian climate were modulated by meridional migrations of the {S}outh {P}acific {C}onvergence {Z}one {L}ast deglacial {P}orites corals revealed reduced linear extension rates (1.0 +/- 0.6 cm year-1) compared to today (1.6 +/- 0.3 cm year-1)},
  keywords = {deglacial ; coral reefs ; paleoclimate ; meltwater pulse 1{A} ; {T}ahiti ; {IODP} ; {PACIFIQUE} ; {TAHITI} ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{P}aleoceanography and {P}aleoclimatology},
  volume = {39},
  numero = {2},
  pages = {e2022{PA}004585 [21 p.]},
  ISSN = {2572-4517},
  year = {2024},
  DOI = {10.1029/2022pa004585},
  URL = {https://www.documentation.ird.fr/hor/fdi:010089551},
}