Charlie Marshall , Carrie Morrill , Sylvia Dee , Yueyang Jiang , Sue Kim , James Russell
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引用次数: 0
Abstract
Paleoclimate data-model comparison is a vital tool for evaluating climate model performance and constraining predictions of climate change. Paleoclimate records provide an important out-of-sample target to test models in climates with different boundary conditions and improve model physics. General Circulation Models (GCMs) from the Paleoclimate Model Intercomparison Project (PMIP) underestimate temperature changes in tropical Africa during key periods in the past, calling into question model predictions of future climate change in this region. We compare a new suite of 8 temperature records from tropical African lakes derived from glycerol dialkyl glycerol tetraethers (GDGTs) to simulations of the Last Glacial Maximum (LGM, 21 kya) and mid-Holocene (MH, 6 kya) from PMIP3 and PMIP4, and find that there is significant proxy/model temperature disagreement during both periods; GCMs are over 2 °C cooler than proxies during the MH, and 2 °C warmer than proxies during the LGM. This could arise from issues with GCMs or the GDGT records. We use a proxy system model (PSM) to investigate multiple potential sources of proxy uncertainty, including non-stationarity in the relationship between air and lake temperature, seasonality, and calibration error. We find that proxy system error can account for significant portions of this discrepancy during the MH (up to 80%) assuming the maximum possible error for each potential source, but not during the LGM. Our findings highlight potential areas for improvement in interpretation of proxy records by explicitly modeling and quantifying uncertainty in reconstructed temperatures.
期刊介绍:
Quaternary Science Reviews caters for all aspects of Quaternary science, and includes, for example, geology, geomorphology, geography, archaeology, soil science, palaeobotany, palaeontology, palaeoclimatology and the full range of applicable dating methods. The dividing line between what constitutes the review paper and one which contains new original data is not easy to establish, so QSR also publishes papers with new data especially if these perform a review function. All the Quaternary sciences are changing rapidly and subject to re-evaluation as the pace of discovery quickens; thus the diverse but comprehensive role of Quaternary Science Reviews keeps readers abreast of the wider issues relating to new developments in the field.