Preface

Once again, for the third time, in 2009, the Serbian Academy of Sciences and Arts organized an international symposium on the occasion of the birth anniversary of Milutin Milankovitch. As in 2004, the 2009 symposium was held under the patronage of the United Nations Educational, Scientific and Cultural Organization (UNESCO). What were the motives, supported by UNESCO, that led the Academy to organize another Milankovitch symposium 5 years after the second one? Several considerations were behind this move. Paleoclimate, with its records of numerous drastic climatic changes, is a rich reservoir of real-world information on the patterns of change in the earth’s climate system. While in 2004 there were some people skeptical about global warming and also of it being a phenomenon caused by man’s activities, in 2009 there were not many left of either kind. Thus, understanding paleoclimate, following in the footsteps of Milankovitch, not only adds to our basic knowledge of the history of the world we live in, but it also adds to our abilities to anticipate future climate changes as the emission of greenhouse gasses by the increasing world population continues with little abatement in sight. This last point was brought into focus recently by the work of James Hansen and collaborators who pointed out that the information on which way the earth’s climate is going should best rely on three sources: observations, results of numerical models, and paleoclimate data. This is because the former two sources have limitations: observations are obtained from the earth’s climate system which is now not in equilibrium, and numerical models include processes that are insufficiently understood and thus contain errors, and in their most advanced forms cannot be run for as long as one would wish. Paleoclimate data, on the other hand, are obtained from the time when the earth’s climate system was close to equilibrium, such as the time of the maximum extent of the last ice age, and the time when there was no ice cover on the earth, some 40 million years ago. With this new awareness of the significance of paleoclimate in the context of the climate change in progress, it seemed appropriate to open the 2009 symposium with a brief review of the present climate change situation, especially in view of the post 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). Given that the proceedings are being printed about 2 years after the symposium was held, the review paper by Richard Somerville included here has been updated so as to contain information on global climate during the 2 years following the symposium: 2009 and 2010. The review of the present climatic condition is followed by invited presentations reporting the progress made in the field of paleoclimate science. The session on paleoclimate started on Tuesday, 22 September and ended on Thursday, 24