Southward Migration of the Intertropical Convergence Zone Through the Holocene

Abstract

Titanium and iron concentration data from the anoxic Cariaco Basin, off the Venezuelan coast, can be used to infer variations in the hydrological cycle over northern South America during the past 14,000 years with subdecadal resolution. Following a dry Younger Dryas, a period of increased precipitation and riverine discharge occurred during the Holocene "thermal maximum." Since approximately 5400 years ago, a trend toward drier conditions is evident from the data, with high-amplitude fluctuations and precipitation minima during the time interval 3800 to 2800 years ago and during the "Little Ice Age." These regional changes in precipitation are best explained by shifts in the mean latitude of the Atlantic Intertropical Convergence Zone (ITCZ), potentially driven by Pacific-based climate variability. The Cariaco Basin record exhibits strong correlations with climate records from distant regions, including the high-latitude Northern Hemisphere, providing evidence for global teleconnections among regional climates.

The Medieval Climate Anomaly and Little Ice Age in Chesapeake Bay and the North Atlantic Ocean

“…8). The general shape of the Cariaco %Ti record (Haug et al, 2001) (Fig. 8b) resembles that for MD03-2661 δ 18 O foram variability (Fig.…”

Paleohydrological changes during the last deglaciation in Northern Brazil

“…Drier conditions are also reported in the Bolivian cordillera (van't Veer et al, 2000) A reduction of 60 % of the Amazon discharge, as compared to the modern flow, is noticed from the Amazon fan sediments (Figure 5h, Maslin and Burns, 2000) and reduced precipitations in northern Amazonia (Peterson et al, 2000) accompanied by the development of a dry savanna are inferred from the Cariaco Trench (Haug et al, 2001;Hughen et al, 2004). Oppositely, the YD has been interpreted as more 2000).…”

Dune ages in the sand deserts of the southern Sahara and Sahel

“…Grove 1958, Grove andWarren 1968). We also expected to see progressively younger ages spreading from north to south due to dune reactivation during the late Holocene as the ITCZ moved south (Haug et al 2001), wetlands dried out progressively from north to south (Lézine et al 2011) and the desert expanded southwards again. However, this model does not appear to be supported by the data.…”

“…Tracing the low salinity zone associated with the marine ITCZ, Arbuszewski et al (2013) estimate that the ITCZ moved latitudinally over the ocean and shifted at least 7° south during the LGM to a latitude of 2° South. During the early Holocene there was a northward shift in the ITCZ and the monsoon rain-belt towards 10° or 12° North, from which it has subsequently shifted south to around 5° North at the present day (Haug et al, 2001). …”