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The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. 
FIGURE 2.4 Global extent of terrestrial (pollen) and ice core (isotopic) evidence where the Younger Dryas cooling (11,500 – 13,000 BP) has been found. While northern hemispheric evidence is consistently strong for cooling, southern hemispheric sites contain controversial evidence and in some cases lack of evidence for a cooling during the YD interval. Possible upwelling in the Cariaco Basin during this time is also indicated, attributed to trade wind increase. Strong cooling ranges from 13-4° C; controversial means some sites show cooling and some do not (after Peteet, 1995). decrease was not observed on the western Panamanian slope (Piperno et al., l990; Bush et al., l992). South AmericaIn Colombia, the El Abra stadial (a Younger Dryas equivalent) was a cold interval about 13,000-11,700 years ago characterized by low temperature and low precipitation (van der Hammen and Hooghiemstra, 1995). The upper forest line during the stadial was 600-800 m lower than today, and average temperatures were about 4-6°C lower than today. This evi-
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