TP: site elevation estimated from Google Earth

(1) The most recent stalagmite ?18O values are anticorrelated with Basin of Mexico precipitation, showing our record to be a robust proxy for rainfall amount. (2) Smothed ?18O data and Tacubaya wet season (May through November, MJJASON, comprising 95% of the annual total) rainfall (1880?2010 CE) is strongly anticorrelated. (3) Observational studies of tropical rainfall

9 yr smoothed rainfall and ?18O data (1878?1988 CE) are correlated at r=-0.89, suggesting a a ca. 9yr transit time (the chronology was adjusted accordingly)

Lachniet, M. S., Bernal, J. P., Asmerom, Y., Polyak, V. and Piperno, D.: A 2400 yr Mesoamerican rainfall reconstruction links climate and cultural change, Geology, 40(3), 259–262, doi:10.1130/g32471.1, 2012.

d18O (SP12LAMX01A): interpretation3_scope: '' has been replaced by 'isotope'
d18O (SP12LAMX01A): interpretation4_scope: '' has been replaced by 'isotope'

Given that the precipitation regime in the study area is quite similar to the one at Brasilia station it is rea- sonable to assume that most of the isotopic fractionation is primarily related to total rainfall amount, which is charac- terized by more negative values during the wet season and more positive ones during the dry season.

Novello, V. F., Cruz, F. W., Karmann, I., Burns, S. J., Strikis, N. M., Vuille, M., Cheng, H., Lawrence Edwards, R., Santos, R. V., Frigo, E. and Barreto, E. A. S.: Multidecadal climate variability in Brazil’s Nordeste during the last 3000 years based on speleothem isotope records, Geophysical Research Letters, 39(23), n/a–n/a, doi:10.1029/2012gl053936, 2012.

d18O (SP12NOBR00A): interpretation4_scope: '' has been replaced by 'isotope'

Finnigan Delta Plus ratio mass spectrometer

Internal precision is ?0.1% for ?18O and ?13C

The major features (growht banding thickness) are replicated in other speleothems from the same cave and other caves in the region

Because Bat Cave relative humidity today varies between 70% and 95%, dry conditions are interpreted, in part, to reflect greater kinetic fractionation, resulting in higher ?13C and ?18O values in the stalagmite calcite. The stalagmite was sampled close to the entrance