@article {314,
	title = {Postglacial changes in El Nino and La Nina behavior},
	journal = {Geology},
	volume = {38},
	year = {2010},
	note = {id: 1985; PT: J; UT: WOS:000273346200011},
	pages = {43-46},
	abstract = {Paleoclimate reconstructions suggest distinctive changes in the Ell Nino-Southern Oscillation (ENSO), the dominant mode of tropical climate variability, over the last glacial cycle and throughout the Holocene. However, to the best of our knowledge, no studies provide parallel reconstructions of warm (El Nino) and cold (La Nina) phase variability, thus precluding distinction between variations in ENSO activity and the mean state of the tropical Pacific. Here we provide the first such records, generated using molecular organic geochemical proxies in a sediment core from the Peru margin region. The opposing influences of El Nino and La Nina on coastal upwelling and phytoplankton community structure produce distinct sedimentary sterol records describing the evolution of each ENSO phase. We document changes in surface ocean productivity on the Peru margin over the past 16 ka that indicate enhanced La Nina-like conditions alone during deglaciation, but concomitant increases in both El Nino and La Nina activity during the past 2 ka. We propose that the preponderance of La Nina-like conditions prior to 11.5 ka reflects the influence of waning glacial boundary conditions. By contrast, warm and cold phase covariability during the late Holocene suggests centennial-scale changes in ENSO activity, rather than the Pacific mean state, driven by tropical insolation.},
	issn = {0091-7613},
	doi = {10.1130/G30366.1},
	author = {Makou, Matthew C. and Eglinton, Timothy I. and Oppo, Delia W. and Hughen, Konrad A.}
}
@article { ISI:000267640400001,
	title = {High-sensitivity measurement of diverse vascular plant-derived biomarkers in high-altitude ice cores},
	journal = {GEOPHYSICAL RESEARCH LETTERS},
	volume = {36},
	year = {2009},
	month = {JUL 3},
	type = {Article},
	abstract = {Semi-volatile organic compounds derived from burned and fresh vascular plant sources and preserved in high-altitude ice fields were detected and identified through use of recently developed analytical tools. Specifically, stir bar sorptive extraction and thermal desorption coupled with gas chromatography/time-of-flight mass spectrometry allowed measurement of multiple biomarkers in small sample volumes (<= 30 ml). Among other compounds of interest, several diterpenoids, which suggest inputs from conifers and conifer burning, were identified in post-industrial era and older Holocene ice from the Sajama site in the Bolivian Andes, but not in a glacial period sample, consistent with aridity changes. Differences in biomarker assemblages between sites support the use of these compounds as regionally constrained recorders of vegetation and climate change. This study represents the first application of these analytical techniques to ice core research and the first indication that records of vegetation fires may be reconstructed from diterpenoids in ice. Citation: Makou, M. C., L. G. Thompson, D. B. Montlucon, and T. I. Eglinton (2009), High-sensitivity measurement of diverse vascular plant-derived biomarkers in high-altitude ice cores, Geophys. Res. Lett., 36, L13501, doi: 10.1029/2009GL037643.},
	issn = {0094-8276},
	doi = {10.1029/2009GL037643},
	author = {Makou, Matthew C. and Thompson, Lonnie G. and Montlu{\c c}on, Daniel B. and Eglinton, Timothy I.}
}
