Late Quaternary behavior of the East African monsoon and the importance of the Congo Air Boundary

Jessica E. Tierney, James M. Russell, Jaap S. Sinninghe Damsté, Yongsong Huang, Dirk Verschuren

Research output: Contribution to journalArticlepeer-review

168 Scopus citations

Abstract

Both Atlantic and Indian Ocean climate dynamics exert influence over tropical African hydroclimate, producing complex patterns of convergence and precipitation. To isolate the Indian Ocean influence on African paleohydrology, we analyzed the deuterium/hydrogen ratio of higher plant leaf waxes (δDwax) in a 25 000-year sediment record from Lake Challa (3° S, 38° E) in the easternmost area of the African tropics. Whereas both the seismic record of inferred lake level fluctuations and the Branched and Isoprenoidal Tetraether (BIT) index proxy record changes in hydrology within the Challa basin, δDwax, as a proxy for the isotopic composition of precipitation (δDP) is interpreted as a tracer of large-scale atmospheric circulation that integrates the history of the moisture transported to the Lake Challa area. Specifically, based on modern-day isotope-rainfall relationships, we argue that Lake Challa δDwax reflects the intensity of East African monsoon circulation. The three hydrological proxy records show generally similar trends for the last 25 000 years, but there are important differences between them, primarily during the middle Holocene. We interpret this deviation of δDwax from local hydrological history as a decoupling of East African monsoon intensity - which heavily influences the isotopes of precipitation in East Africa today - from rainfall amount in the Challa basin. In combination, the hydrological proxy data from Lake Challa singularly highlight zonal gradients in tropical African climate that occur over a variety of timescales, suggesting that the Congo Air Boundary plays a fundamental role in controlling hydroclimate in the African tropics.

Original languageEnglish (US)
Pages (from-to)798-807
Number of pages10
JournalQuaternary Science Reviews
Volume30
Issue number7-8
DOIs
StatePublished - Apr 2011
Externally publishedYes

Keywords

  • African climate
  • Congo Air Boundary
  • Holocene climate
  • Hydrogen isotopes
  • Paleohydrology

ASJC Scopus subject areas

  • Global and Planetary Change
  • Ecology, Evolution, Behavior and Systematics
  • Archaeology
  • Archaeology
  • Geology

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