2025-06-19 ブラウン大学
＜関連情報＞
アフリカ北西部の降雨体制は鮮新世から更新世への移行期において根本的に変化していない Fundamentally unchanged northwestern African rainfall regimes across the Plio-Pleistocene transition
Bryce A. Mitsunaga, Amy M. Jewell, Solana Buchanan, Anya J. Crocker, […] , and James M. Russell
Science Advances Published:20 Jun 2025
DOI:https://doi.org/10.1126/sciadv.ads3149
Abstract
Northern African climate is characterized by strongly contrasting wet summers and dry winters. Dust exported by the northeasterly trade (Harmattan) winds creates marine sedimentary records that have been long interpreted to show that northern African climate became drier and more variable across the Pliocene-Pleistocene boundary [2.58 million years ago (Ma)], when global climate cooled and high-latitude glacial-interglacial cycles intensified. However, questions about the impact of summer rainfall on winter dust fluxes and thus the history of the African summer monsoons remain. We present a leaf wax hydrogen isotope record from offshore northwestern Africa that demonstrates that rainfall regimes remained stable and varied solely in response to 21,000-year cycles in summer insolation from 3.5 to 2.5 Ma. We infer that the summer rains and winter winds respond to different climate forcings, with summer rainfall driven by solar radiation over the northern African landmass and the winter trades affected by high-latitude climate and meridional temperature gradients.
