Lake-Level Influences on Chironomid-Based Reconstructions of Paleotemperature

This award is for support of a study to determine the influence of lake-level changes on chironomid-based temperature estimates. A transect of cores from within each of two lakes in northern Maine will be examined for evidence of past water levels. Chironomid analysis will be performed on cores from both lakes. Geologic/chronologic evidence of Younger Dryas-age ice readvance in northern Maine will provide the data necessary to apply a well-developed glaciological model to determine the range of temperature and precipitation that could possibly have prevailed during this period. Chironomid estimates of temperature will be reconciled with the temperature range derived from the glaciological model, and the transfer function will also be refined with respect to lake-level. The new chironomid/lake-level transfer function will then be applied to Holocene sediments from the two lakes

Determining Patterns of Abrupt Climate Change during the Last Glacial-Interglacial Transition (LGIT) in the Southern Hemisphere

This proposal will fund the development of a continuous, isotopically-dated paleochironomid and pollen record of deglacial climate fluctuations from lake sediments located in climatically sensitive sites along the Southern Alps, New Zealand. Detailed investigations will be carried out for the Last Glacial-Interglacial Transition (LGIT) at Boundary Stream Tarn, Quagmire Tarn, and Kettlehole Bog to establish the sequence of deglacial climate events and to facilitate comparisons with other well-dated northern and southern records. The primary scientific objectives of the project are to determine: 1) the pattern and magnitude of past climate change; 2) whether changes recorded show an in-phase or out-of-phase relationship with the Northern Hemisphere; and 3) whether the Antarctic signature extends into the southwest Pacific region. These results will facilitate differentiation among viable hypotheses concerning abrupt global climate change. Detailed chironomid analysis, interpreted by a newly developed chironomid-temperature transfer function, will be carried out on Quagmire Tarn and Kettlehole Bog LGIT-age sediment and pollen analysis will be conducted on Quagmire Tarn. This project will provide the opportunity for three undergraduate students to conduct independent research. The project will also enhance greater understanding in global paleoclimatology and provide opportunities for collaboration among researchers through the publication of a photographic key to fossil chironomids

The Anatomy of Last Glacial Maximum (LGM) Climate Change in the Southern Hemisphere Mid-Latitudes: Paleoecological Temperature Reconstructions from Terrestrial Archives

The objective of this research is to test if leading hypotheses about drivers of global ice ages explain climate change in the Southern Hemisphere mid-latitudes. The research establishes the timing, magnitude, and structure of southern mid-latitude Last Glacial Maximum climate from two sites bordering the Southern Alps, New Zealand, by reconstructing temperature changes from continuous, isotopically dated, paleo-chironomid and pollen re-cords. Hypotheses about what drives ice age climate change remain clouded with ambiguities because the timing and magnitude of maximum ice age cooling (Last Glacial Maximum, LGM) does not appear to match between the Northern and Southern Hemispheres. Northern solar insolation is held responsible for driving Southern Hemisphere climate changes even though the intensity and duration of southern insolation is out of phase with that of the north. Apparent mismatches in the timing of LGM climate changes between the hemispheres cannot be adequately explained by northern insolation forcing alone. High resolution records of the precise timing and magnitude of climate change in the mid-latitudes of the Southern Hemisphere are strategic for understanding the forces driving global glacial cycles and identifying interhemispheric leads and lags in the climate system. Terrestrial archives (lake sediment) from southern New Zealand are ideal for such research because the region is sensitive to subtle changes in the circumpolar westerlies and supports distinct vegetation and chironomid (non-biting midge fly) ecological zones. Pollen and chironomids from this region have known relationships to temperature and can provide continuous, datable, quantitative estimates of terrestrial temperature change. This research has two primary goals: 1) to develop paleotemperature reconstructions for the western and eastern margins of the Southern Alps from two lakes located outside LGM moraine belts using pollen and chironomid temperature inference models, and 2) to determine the precise timing and duration of LGM climate changes for this location using detailed AMS radiocarbon dating. The project will provide a comprehensive paleoclimate data set that will be directly applicable to testing hypotheses about forcing mechanisms responsible for major climate changes. The proposed research will provide training opportunities for four undergraduate students per semester. It will develop and enhance collaborative ties between the University of Maine and several New Zealand institutions. Benefits to society include documenting the temporal and spatial extent and magnitude of climatological phenomena to better understand the LGM climate of the southern mid-latitudes and testing the viability of several hypotheses about mechanisms that drive ice age change

NA2750 Ann Deiffenbacher-Krall, interviewed by Adam Lee Cilli

2750 Ann Dieffenbacher-Krall, interviewed by Adam Lee Cilli, January 22, 2014, in her office in Murray Hall at the University of Maine, Orono. Dieffenbacher-Krall talks about working with other members of the Climate Change Institute, particularly her adviser George Jacobson; conducting research on lake cores in New Zealand; her research methods; the reality of anthropogenic climate change; and the opportunities for interdisciplinary research offered by the CCI. Text: 7 pp. transcript Recording: mfc_na2750_audio001 36 minutes Photo provided by the Climate Change Institute.https://digitalcommons.library.umaine.edu/mf192/1009/thumbnail.jp

Propsilocerus Kieffer (Diptera: Chironomidae) from the Nearctic

Larvae of the chironomid genus Propsilocerus Kieffer (Diptera: Chironomidae), known from the Palaearctic region and from subfossil larval head capsules in North America, have been found living in remote British Columbia, Canada. We review the morphology and ecology of the taxon in North America, and report and interpret the subfossil occurrences. Although the species appears to be undescribed, we refrain from a formal taxonomic description based on the larva alone pending discovery of the full life history

Quantifying climate change in Huelmo mire (Chile, Northwestern Patagonia) during the Last Glacial Termination using a newly developed chironomid-based temperature model

Artículo de publicación ISIThe development of quantitative temperature reconstructions in regions of paleoclimate interest is an important step for providing reliable temperature estimates in that region. Fossil chironomid assemblages have been studied in Patagonia showing great promise for reconstructing paleotemperatures; however there is still a lack of robust temperature inference models in that area. To contribute to the understanding of climate change, a transfer function using chironomids preserved in 46 lakes in Chile and Argentina was developed. The best performing model to infer the mean air temperature of the warmest month was a 3-component WA-PLS model with a coefficient of correlation (r2jack) of 0.56, a root mean square error of prediction (RMSEP) of 1.69[grados]C and a maximum bias of 2.07[grados]C. This model was applied to the chironomids preserved in the sediment of the Huelmomire (41 [grados]31 'S, 73[grados]00 'W), in the lake district of northwestern Patagonia. The reconstruction showed several cold spells (one at 13,200 to 13,000 cal yr BP and a cooling trend between 12,600 and 11,500 cal yr BP) associated with the Younger Dryas and/or Huelmo.Mascardi Cold Reversal (HMCR). Our findings support climate models proposing fast acting inter-hemispheric coupling mechanisms including the recently proposed bipolar atmospheric and/or bipolar ocean teleconnections rather than a bipolar see-saw modelJM acknowledges G. Denton and COMER Science Foundation for providing financial support and M. Colombres for lab assistance

A revised age for the Kawakawa/Oruanui tephra, a key marker for the Last Glacial Maximum in New Zealand

The Kawakawa/Oruanui tephra (KOT) is a key chronostratigraphic marker in terrestrial and marine deposits of the New Zealand (NZ) sector of the southwest Pacific. Erupted early during the Last Glacial Maximum (LGM), the wide distribution of the KOT enables inter-regional alignment of proxy records and facilitates comparison between NZ climatic variations and those from well-dated records elsewhere. We present 22 new radiocarbon ages for the KOT from sites and materials considered optimal for dating, and apply Bayesian statistical methods via OxCal4.1.7 that incorporate stratigraphic information to develop a new age probability model for KOT. The revised calibrated age, ±2 standard deviations, for the eruption of the KOT is 25,360 ± 160 cal yr BP. The age revision provides a basis for refining marine reservoir ages for the LGM in the southwest Pacific