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399 results on '"Abbott, Mark B."'

23. Synchronous interhemispheric Holocene climate trends in the tropical Andes

Author

Polissar, Pratigya J, Abbott, Mark B, Wolfe, Alexander P, Vuille, Mathias, and Bezada, Maximiliano

Subjects
Climate Action, Altitude, Carbon, Climate, Geography, Geologic Sediments, Nitrogen, Pacific Ocean, Principal Component Analysis, Rain, Seasons, Seawater, South America, Temperature, Time Factors, Venezuela, Bolivia, Caribbean, El Nino-Southern Oscillation, Milankovitch, El Niño-Southern Oscillation
Abstract

Holocene variations of tropical moisture balance have been ascribed to orbitally forced changes in solar insolation. If this model is correct, millennial-scale climate evolution should be antiphased between the northern and southern hemispheres, producing humid intervals in one hemisphere matched to aridity in the other. Here we show that Holocene climate trends were largely synchronous and in the same direction in the northern and southern hemisphere outer-tropical Andes, providing little support for the dominant role of insolation forcing in these regions. Today, sea-surface temperatures in the equatorial Pacific Ocean modulate rainfall variability in the outer tropical Andes of both hemispheres, and we suggest that this mechanism was pervasive throughout the Holocene. Our findings imply that oceanic forcing plays a larger role in regional South American climate than previously suspected, and that Pacific sea-surface temperatures have the capacity to induce abrupt and sustained shifts in Andean climate.

Published
2013

27. Lead isotope fingerprinting techniques help identify and quantify 3000 years of atmospheric lead pollution from Laguna Roya, northwestern Iberia

Author

Hewlett Foundation, University of Pittsburgh, Consejo Superior de Investigaciones Científicas (España), Ministerio de Economía y Competitividad (España), Griffore, Melissa P., Shiel, Alyssa E., Rutila, Elizabeth C., Hillman, Aubrey L., Barreiro-Lostres, Fernando, Valero-Garcés, Blas L., Morellón, Mario, Abbott, Mark B., Hewlett Foundation, University of Pittsburgh, Consejo Superior de Investigaciones Científicas (España), Ministerio de Economía y Competitividad (España), Griffore, Melissa P., Shiel, Alyssa E., Rutila, Elizabeth C., Hillman, Aubrey L., Barreiro-Lostres, Fernando, Valero-Garcés, Blas L., Morellón, Mario, and Abbott, Mark B.

Abstract

Legacy pollution research has established that over the past 3000 years, mining and metallurgical activities have resulted in widespread deposition of lead (Pb) pollution. However, there is still a limited understanding of how humans have impacted the long-term cycling of Pb in the environment. We present a 4,000-year lake sediment Pb isotope record from Laguna Roya, northwestern Iberia, that identifies and quantifies the predominant sources of atmospheric Pb pollution. For the first time, Pb isotopic compositions of ancient slag samples dated (∼600 BCE–200 CE) from a mining district in the southwest of the Iberian Peninsula are compared to Pb isotope ratios of Pb pollution deposited contemporaneously in lake sediments. In addition, literature Pb isotope ratios of ores from mining regions throughout Iberia are compared with those of leaded gasoline and coal to identify additional sources of anthropogenic Pb. Deposition of atmospheric Pb pollution begins after 950 BCE, and until 1750 CE, the Pb isotopic composition most resembles the southwestern slag deposits, containing a mixture of Pb ores from southeast Iberia (up to 36%) and southwest Iberia (∼74%). Between 1750 and 1960 CE, Pb pollution is attributed to Pb mining in southcentral Iberia. After 1960 CE, the dominant Pb pollution source (∼85%) is again metal refining in southwestern Iberia, and only ∼15% is from leaded gasoline. Provenance and reconstruction of the temporal and spatial distribution of legacy Pb pollution further our understanding of how humans have affected the biogeochemical cycle of this toxic element in the environment over time.

Published
2023

44. 700,000 years of tropical Andean glaciation

Author

National Science Foundation (US), Valero-Garcés, Blas L. [0000-0003-2214-7057], Rodbell, D. T., Hatfield, R. G., Abbott, Mark B., Chen, C. Y., Woods, A., Stoner, J. S., McGee, D., Tapia, P. M., Bush, M., Valero-Garcés, Blas L., Lehmann, S. B., Mark, S. Z., Weidhaas, N. C., Hillman, Aubrey L., Larsen, D. J., Delgado, G., Katz, S. A., Solada, K. E., Morey, A. E., Finkenbinder, M., Valencia, B., Rozas-Davila, A., Wattrus, N., Colman, S. M., Bustamante, M. G., Kück, J., Pierdominici, S., National Science Foundation (US), Valero-Garcés, Blas L. [0000-0003-2214-7057], Rodbell, D. T., Hatfield, R. G., Abbott, Mark B., Chen, C. Y., Woods, A., Stoner, J. S., McGee, D., Tapia, P. M., Bush, M., Valero-Garcés, Blas L., Lehmann, S. B., Mark, S. Z., Weidhaas, N. C., Hillman, Aubrey L., Larsen, D. J., Delgado, G., Katz, S. A., Solada, K. E., Morey, A. E., Finkenbinder, M., Valencia, B., Rozas-Davila, A., Wattrus, N., Colman, S. M., Bustamante, M. G., Kück, J., and Pierdominici, S.

Abstract

Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores1; these interhemispheric connections may have existed during previous glacial cycles.

Published
2022

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