Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis
Subfossil pollen and plant macrofossil data derived from C-14-dated sediment profiles can provide quantitative information on glacial and interglacial climates. The data allow climate variables related to growing-season warmth, winter cold, and plant-available moisture to be reconstructed. Continental-scale reconstructions have been made for the mid-Holocene (MH, around 6 ka) and Last Glacial Maximum (LGM, around 21 ka), allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change. The synthesis of the available MH and LGM climate reconstructions and their uncertainties, obtained using modern-analogue, regression and model-inversion techniques, is presented for four temperature variables and two moisture variables. Reconstructions of the same variables based on surface-pollen assemblages are shown to be accurate and unbiased. Reconstructed LGM and MH climate anomaly patterns are coherent, consistent between variables, and robust with respect to the choice of technique. They support a conceptual model of the controls of Late Quaternary climate change whereby the first-order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance.
Keywords: Pollen ; Plant macrofossils ; Palaeovegetation palaeoclimate reconstructions ; Reconstruction uncertainties ; Mid-Holocene ; Last glacial maximum ; Climate model evaluation ; Last Glacial Maximum ; Eastern North-America ; General-Circulation Model ; Pmip2 Coupled Simulations ; Modern Analog Technique ; Plant Functional Types ; Past 21,000 Years ; Lake Status Data ; Leaf-Area Index ; C-14 Yr Bp
Record created on 2011-12-16, modified on 2016-08-09