Bering Land Bridge se formou surpreendentemente tarde durante a última era glacial, segundo estudo
Um novo estudo que reconstrói a história do nível do mar no Estreito de Bering mostra que a Bering Land Bridge que liga a Ásia à América do Norte não surgiu até cerca de 35.700 anos atrás, menos de 10.000 anos antes do auge da última era glacial...
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)
Estreito de Bering congelado perto de Nome/Alasca. Crédito: Crissi /Wikimedia Commons, CC BY-SA
Um novo estudo que reconstrói a história do nível do mar no Estreito de Bering mostra que a Bering Land Bridge que liga a Ásia à América do Norte não surgiu até cerca de 35.700 anos atrás, menos de 10.000 anos antes do auge da última era glacial (conhecida como Último Máximo Glacial).
As novas descobertas, publicadas na semana de 26 de dezembro na Proceedings of the National Academy of Sciences , indicam que o crescimento das camadas de gelo – e a resultante queda no nível do mar – ocorreu surpreendentemente rápido e muito mais tarde no ciclo glacial do que estudos anteriores haviam feito. sugerido.
“Isso significa que mais de 50% do volume global de gelo no Último Máximo Glacial cresceu depois de 46.000 anos atrás”, disse Tamara Pico, professora assistente de ciências da Terra e planetárias na UC Santa Cruz e autora correspondente do artigo. “Isto é importante para entender as reações entre o clima e os mantos de gelo, porque implica que houve um atraso substancial no desenvolvimento dos mantos de gelo depois que as temperaturas globais caíram”.
Os níveis globais do mar caem durante as eras glaciais, à medida que mais e mais água da Terra fica presa em enormes mantos de gelo, mas o momento desses processos tem sido difícil de definir. Durante o Último Máximo Glacial, que durou de cerca de 26.500 a 19.000 anos atrás, mantos de gelo cobriram grandes áreas da América do Norte. Os níveis do mar dramaticamente mais baixos revelaram uma vasta área de terra conhecida como Beringia, que se estendia da Sibéria ao Alasca e sustentava manadas de cavalos, mamutes e outros animais do Pleistoceno. À medida que as camadas de gelo derreteram, o Estreito de Bering foi inundado novamente cerca de 13.000 a 11.000 anos atrás.
As novas descobertas são interessantes em relação à migração humana porque encurtam o tempo entre a abertura da ponte terrestre e a chegada dos humanos às Américas. O momento da migração humana para a América do Norte permanece sem solução, mas alguns estudos sugerem que as pessoas podem ter vivido na Beríngia durante o auge da era glacial.
“As pessoas podem ter começado a atravessar assim que a ponte de terra se formou”, disse Pico.
O novo estudo usou uma análise de isótopos de nitrogênio em sedimentos do fundo do mar para determinar quando o Estreito de Bering foi inundado durante os últimos 46.000 anos, permitindo que a água do Oceano Pacífico fluísse para o Oceano Ártico. O primeiro autor, Jesse Farmer, da Universidade de Princeton, liderou a análise de isótopos, medindo as proporções de isótopos de nitrogênio nos restos de plâncton marinho preservados em núcleos de sedimentos coletados do fundo do mar em três locais no Oceano Ártico ocidental. Devido às diferenças na composição do nitrogênio das águas do Pacífico e do Ártico, Farmer foi capaz de identificar uma assinatura de isótopos de nitrogênio indicando quando a água do Pacífico fluiu para o Ártico.
Pico, especialista em modelagem do nível do mar, comparou os resultados de Farmer com modelos do nível do mar baseados em diferentes cenários para o crescimento das camadas de gelo.
“O mais empolgante para mim é que isso fornece uma restrição completamente independente no nível global do mar durante esse período”, disse Pico. "Algumas das histórias de camadas de gelo propostas diferem bastante, e pudemos observar qual seria o nível do mar previsto no Estreito de Bering e ver quais são consistentes com os dados de nitrogênio."
Os resultados apoiam estudos recentes que indicam que os níveis globais do mar eram muito mais altos antes do Último Máximo Glacial do que as estimativas anteriores sugeriam, disse ela. O nível médio global do mar durante o Último Máximo Glacial foi cerca de 130 metros (425 pés) mais baixo do que hoje. O nível real do mar em um local específico, como o Estreito de Bering, no entanto, depende de fatores como a deformação da crosta terrestre pelo peso das camadas de gelo.
"É como socar a massa de pão - a crosta afunda sob o gelo e sobe nas bordas", disse Pico. "Além disso, as camadas de gelo são tão grandes que têm efeitos gravitacionais na água. Eu modelo esses processos para ver como o nível do mar varia ao redor do mundo e, neste caso, para observar o Estreito de Bering."
As descobertas implicam uma relação complicada entre o clima e o volume global de gelo e sugerem novos caminhos para investigar os mecanismos subjacentes aos ciclos glaciais.
Mais informações: Farmer, Jesse R. et al, O Estreito de Bering foi inundado 10.000 anos antes do Último Máximo Glacial, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2206742119 .
Informações do periódico: Proceedings of the National Academy of Sciences