TY  - JOUR
A1  - Lechleitner, Franziska A.
A1  - Breitenbach, Sebastian Franz Martin
A1  - Rehfeld, Kira
A1  - Ridley, Harriet E.
A1  - Asmerom, Yemane
A1  - Prufer, Keith M.
A1  - Marwan, Norbert
A1  - Goswami, Bedartha
A1  - Kennett, Douglas J.
A1  - Aquino, Valorie V.
A1  - Polyak, Victor
A1  - Haug, Gerald H.
A1  - Eglinton, Timothy I.
A1  - Baldini, James U. L.
T1  - Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw
JF  - Scientific reports
N2  - The presence of a low-to mid-latitude interhemispheric hydrologic seesaw is apparent over orbital and glacial-interglacial timescales, but its existence over the most recent past remains unclear. Here we investigate, based on climate proxy reconstructions from both hemispheres, the inter-hemispherical phasing of the Intertropical Convergence Zone (ITCZ) and the low-to mid-latitude teleconnections in the Northern Hemisphere over the past 2000 years. A clear feature is a persistent southward shift of the ITCZ during the Little Ice Age until the beginning of the 19th Century. Strong covariation between our new composite ITCZ-stack and North Atlantic Oscillation (NAO) records reveals a tight coupling between these two synoptic weather and climate phenomena over decadal-to-centennial timescales. This relationship becomes most apparent when comparing two precisely dated, high-resolution paleorainfall records from Belize and Scotland, indicating that the low-to mid-latitude teleconnection was also active over annual-decadal timescales. It is likely a combination of external forcing, i.e., solar and volcanic, and internal feedbacks, that drives the synchronous ITCZ and NAO shifts via energy flux perturbations in the tropics.
Y1  - 2017
U6  - https://doi.org/10.1038/srep45809
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Hemingway, Jordon Dennis
A1  - Hilton, Robert G.
A1  - Hovius, Niels
A1  - Eglinton, Timothy I.
A1  - Haghipour, Negar
A1  - Wacker, Lukas
A1  - Chen, Meng-Chiang
A1  - Galy, Valier V.
T1  - Microbial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils
JF  - Science
N2  - Lithospheric organic carbon ("petrogenic"; OCpetro) is oxidized during exhumation and subsequent erosion of mountain ranges. This process is a considerable source of carbon dioxide (CO2) to the atmosphere over geologic time scales, but the mechanisms that govern oxidation rates in mountain landscapes are poorly constrained. We demonstrate that, on average, 67 +/- 11% of the OCpetro initially present in bedrock exhumed from the tropical, rapidly eroding Central Range of Taiwan is oxidized in soils, leading to CO2 emissions of 6.1 to 18.6 metric tons of carbon per square kilometer per year. The molecular and isotopic evolution of bulk OC and lipid biomarkers during soil formation reveals that OCpetro remineralization is microbially mediated. Rapid oxidation in mountain soils drives CO2 emission fluxes that increase with erosion rate, thereby counteracting CO2 drawdown by silicate weathering and biospheric OC burial.
Y1  - 2018
U6  - https://doi.org/10.1126/science.aao6463
SN  - 0036-8075
SN  - 1095-9203
VL  - 360
IS  - 6385
SP  - 209
EP  - +
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Lechleitner, Franziska A.
A1  - Baldini, James U. L.
A1  - Breitenbach, Sebastian Franz Martin
A1  - Fohlmeister, Jens Bernd
A1  - McIntyre, Cameron
A1  - Goswami, Bedartha
A1  - Jamieson, Robert A.
A1  - van der Voort, Tessa S.
A1  - Prufer, Keith
A1  - Marwan, Norbert
A1  - Culleton, Brendan J.
A1  - Kennett, Douglas J.
A1  - Asmerom, Yemane
A1  - Polyak, Victor
A1  - Eglinton, Timothy I.
T1  - Hydrological and climatological controls on radiocarbon concentrations in a tropical stalagmite
JF  - Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society
N2  - Precisely-dated stalagmites are increasingly important archives for the reconstruction of terrestrial paleoclimate at very high temporal resolution. In-depth understanding of local conditions at the cave site and of the processes driving stalagmite deposition is of paramount importance for interpreting proxy signals incorporated in stalagmite carbonate. Here we present a sub-decadally resolved dead carbon fraction (DCF) record for a stalagmite from Yok Balum Cave (southern Belize). The record is coupled to parallel stable carbon isotope (delta C-13) and U/Ca measurements, as well as radiocarbon (C-14) measurements from soils overlying the cave system. Using a karst carbon cycle model we disentangle the importance of soil and karst processes on stalagmite DCF incorporation, revealing a dominant host rock dissolution control on total DCF. Covariation between DCF, delta C-13, and U/Ca indicates that karst processes are a common driver of all three parameters, suggesting possible use of delta C-13 and trace element ratios to independently quantify DCF variability. A statistically significant multi-decadal lag of variable length exists between DCF and reconstructed solar activity, suggesting that solar activity influenced regional precipitation in Mesoamerica over the past 1500 years, but that the relationship was non-static. Although the precise nature of the observed lag is unclear, solar-induced changes in North Atlantic oceanic and atmospheric dynamics may play a role. (C) 2016 Elsevier Ltd. All rights reserved.
KW  - Stalagmite
KW  - Tropics
KW  - Radiocarbon
KW  - Trace elements
KW  - Hydroclimate
Y1  - 2016
U6  - https://doi.org/10.1016/j.gca.2016.08.039
SN  - 0016-7037
SN  - 1872-9533
VL  - 194
SP  - 233
EP  - 252
PB  - Elsevier
CY  - Oxford
ER  -