ES2 Node - Environment, Palaeoenvironment and Environmental Change Network

28th IAS Meeting of Sedimentology | Second Circular

If we can interpret the present and read the past, we can accept the challenge of the future

Present environment can be considered as a dynamic system of emergent complexity, product of the many interactions -feedbacks, couplings, perturbations, inductions, metachronicities,… - stablished amongst its constituent parts -basically the lithosphere, the atmosphere, the hydrosphere and the biosphere; playing humans an increasing role among biota. So have to be considered past environments or palaeoenvironments. This complexity demands an integrated, interdisciplinary view of reasearch in both cases.

Present environment, although diverse, is a readily accessible continuum. Many of its properties can be assesed by scientific research obtaining a good idea of processes and products. The interpretation of past environments depends on a detailed knowledge of present environment (principle of uniformitarianism). The present shows us how to read the record of past environmental change.

Past environments are not directly accessible and their remains are discontinuous. To reconstruct them the object of analysis is the archive, a superficial formation (lake or ocean sediment, accumulation of peat, glacier ice, and others) that contains a record of environmental changes. The change itself leaves signals in the archive -structural, textural, mineralogical, biological, and chemical signals for example- which we attempt to interpret. In this sense, palaeoenvironmental reconstruction tries to make the intinerary from present observed properties of the archives to stablish the processes related to their genesis and from those to uncover the past environments that governed them.

Natural archives are thus the memory of the geosystem. Nevertheless, we have to be aware of the fact that progressive and regressive pathways are both likely to have ocurred, so information was sometimes stored and sometimes deleted from the archives. In fact, the further we go back in time the less information can be recovered. It is also important to remind that reconstruction is always partial, as it is impossible to obtain clues of all the complexities, and even some past environments may have had conditions which are not comparable to any present environment.

Even with these constrains, reconstructions provide a huge database of the evolution of the ecosystems. Under ideal circumstances the database of past environments would help us to know the range of different status showed by a given ecosystem through time and the factors, natural and/or anthropogenic, implicated in its changes. It is this background evolution the framework within which to evaluate present environment. The equation quotes to: the present shows us the processes and the products, the past shows us the evolution. Both knowledges have to be integrated for a proper understanding and to put present changes into perspective.