• journal_title：Geology
• Contributor：Matthew S. Lachniet ; Yemane Asmerom ; Stephen J. Burns ; William P. Patterson ; Victor J. Polyak ; Geoffrey O. Seltzer
• Publisher：Geological Society of America
• Date：2004-
• Format：text/html
• Language：en
• Identifier：10.1130/G20797.1
• journal_abbrev：Geology
• issn：0091-7613
• volume：32
• issue：11
• firstpage：957

A δ¹⁸O monsoon rainfall proxy record from a U-Th–dated Costa Rican stalagmite (8840–4920 yr B.P.) documents an early Holocene dry period correlative with the high-latitude 8200 yr B.P. cold event. High δ¹⁸O values between ca. 8300 and 8000 yr B.P. demonstrate reduced rainfall and a weaker monsoon in Central America. A relatively wetter and more stable monsoon was established ca. 7600 yr B.P. The early Holocene dry event suggests a tropical-extratropical teleconnection to the 8200 yr B.P. cold event and a possible association of isthmian rainfall anomalies with high-latitude climate changes. The likely source of such a tropical anomaly is a decrease in Atlantic thermohaline circulation and atmospheric perturbations associated with drainage of proglacial lakes and freshwater discharge into the North Atlantic. A weaker monsoon at 8200 yr B.P. may be linked to wetland contraction and a decrease in methane observed in Greenland ice cores.