Can Past Holocene climates and environments be used as analogs for predicting future environmental responses to global warming?

Given the unexpected extreme climate events that have occurred this summer, what ecosystem responsesmay be expected during the next few decades, or the rapidity of their onset? Our future climate modelsmay be inadequate. Comparing ecosystem response to past climate change is clearly one way to validateour climate models. To do this we need much more accurate (well-dated) and more precise (detailed andwell-correlated) data on ecosystem response. We will focus upon just one area, the eastern Mediterraneanand into the near and Middle East, to determine if there are climate analogues that can be used. We haveselected the Holocene thermal maximum for our first potential analogue. To assess the possible extremesof future temperature and precipitation based upon analogues of past ecosystem response during theHolocene thermal maximum, we are examining the pollen, and other environmental proxy data of some ofthe well-studied lakes of western and southern Iran, and comparing those data to the record of monsoonincursions taken from the playa lakes of northeastern Africa. We are examining the pollen records for clearsignals of precipitation seasonality based upon the plants that that provide the clearest responds to seasonalprecipitation. This is then compared with the ۴۰,۰۰۰-year climate reconstructions made using the BrysonMesoscale Climate Model and using the ۳۰-year monthly means of the best nearby weather station to eachof the lakes. This reveals the relationship between seasonal temperatures and seasonal precipitation for theperiod of interest. The MCM precipitation is used to convert modelled precipitation into effectiveprecipitation which was then entered that into the Langbein and Schumm erosion model, to derive thesediment yield per square kilometer, i.e., past rates of erosion. Finally we inserted the episodes of dry lakeepisodes indicated by core sediments into the sequence to determine under what climate conditions theseevents occurred. Periods of aeolian erosion will be recorded as breaks in the deposition of pollen, and,where available, as dated cycles of the regional dune record. As these lakes filled during the Holocene,episodes of drying became more common, because the lakes became shallower and dried more quickly. Asglobal warming increases and cycles of drought increase, the landscape surrounding the lakes will becomeeven more susceptible to erosion due to reduced vegetation cover. The unprotected ground surface willbe subjected to increased erosion. Dust and sand storms will be increasingly common in the future whenwe can expect not only much warmer temperatures and less rainfall, but also much more quickly exposedand dried lake bottom due to their increased shallowness.