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delta C-13 decreases in the upper western South Atlantic during Heinrich Stadials 3 and 2

Texto completo
Autor(es):
Campos, Marilia C. ; Chiessi, Cristiano M. ; Voigt, Ines ; Piola, Alberto R. ; Kuhnert, Henning ; Mulitza, Stefan
Número total de Autores: 6
Tipo de documento: Artigo Científico
Fonte: Climate of the Past; v. 13, n. 4 APR 18 2017.
Citações Web of Science: 0
Resumo

Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (delta C-13), i.e. delta(CO2atm)-C-13, presumably due to out-gassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present delta C-13 records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1%) during Heinrich Stadials 3 and 2. These delta C-13 decreases are most likely related to millennial-scale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (delta(CO2atm)-C-13). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air-sea gas exchange could have contributed to the observed delta C-13 decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of delta C-13 during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This ``w structure{''} is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3. (AU)

Processo FAPESP: 13/25518-2 - Variabilidade da Corrente do Brasil e seus impactos no clima da América do Sul durante os últimos 30.000 anos
Beneficiário:Marília de Carvalho Campos
Linha de fomento: Bolsas no Brasil - Mestrado
Processo FAPESP: 15/11016-0 - Variabilidade da Corrente do Brasil e seus impactos no clima da América do Sul durante os últimos 30.000 anos: avaliação das temperaturas da superfície do mar através de análises de Mg/Ca
Beneficiário:Marília de Carvalho Campos
Linha de fomento: Bolsas no Exterior - Estágio de Pesquisa - Mestrado
Processo FAPESP: 12/17517-3 - Resposta da porção oeste do Oceano Atlântico às mudanças na circulação meridional do Atlântico: variabilidade milenar a sazonal
Beneficiário:Cristiano Mazur Chiessi
Linha de fomento: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Jovens Pesquisadores