John Dearing Prof. John Dearing Department of Geography University of Liverpool UK If you would like to interview this scientist, please contact Leah Christen. > biographical information > abstract > paper

Biographical Information:

John Dearing is currently Professor of Physical Geography at the University of Liverpool, U.K., and the Chair of PAGES Focus 5 “Past Ecosystem Processes and Human-Environment Interactions”. He gained his PhD from the University of Liverpool in 1979 for research into the use of mineral magnetism in lake sediment-based studies of environmental change, and spent two years developing this research at Lund University, Sweden, where he was the recipient of a Royal Society Fellowship. He returned to the UK to a lecturing post at Coventry University and moved on to the University of Liverpool in 1996. For more than 25 years, he has continued to develop mineral magnetic methods and to reconstruct past human-environment interactions, working at lake-catchment sites in Europe, N. Africa and China. He has published over 100 articles and book chapters. His current research aims to combine past records with mathematical models that together can provide the basis for simulating change in complex terrestrial systems.

Abstract:

Human-environment interactions: past, present and future

Over the past decade, the contribution of paleoclimate reconstructions to our scientific understanding of the present global climate has been acknowledged at the highest international scientific and political levels. This presentation considers the value and scope of extending climate reconstructions to embrace the complexity of interactions between past human activities, climate and ecosystems. It describes the PAGES program Focus 5 “Past Ecosystem Processes and Human-Environment Interactions”: a program promoting and coordinating the analysis of past environmental archives, historical documents and instrumental records in order to provide a sound basis for determining both the nature of human-environment interactions and the appropriate approaches for sustainable management of ecosystems. The program is sub-divided into three sub-programs dealing with fluvial systems (LUCIFS), terrestrial ecosystems (HITE) and lake systems (LIMPACS). Each sub-program has specific objectives and work plans, but all utilize similar or complementary methodologies and techniques to reconstruct past environments. Published examples are used to demonstrate some of the ways in which we can ‘learn from the past’: modern-baseline comparisons; trajectories of change; variability and scale; process-response relationships; complex system behavior; and simulation modeling. It reviews the priorities for the Focus 5 community, including the need to integrate case-studies within biomes, physiographic areas and highly sensitive systems, and the development and testing of mathematical models that can simulate complex human-environment interactions. A new organizational matrix for the regionalization of Focus 5 information is presented that will help promote multi- and inter-disciplinary analyses of existing case-studies within zonal and azonal regions according to the intensity and duration of past human impact. The new scheme will also help identify other regions for which new research is needed, for example highly valued ecosystems, fragile and degraded landscapes, and human societies threatened by projected climate impacts.

Paper:

Human-environment interactions: past, present and future

The long record of global temperatures provided by so-called environmental proxies, such as tree-rings, has provided the vital perspective to justify arguments for a rising trend over the past century, and uniquely high temperatures over the past decade. This presentation extends the idea of climate reconstruction to include long records of ecosystem change and human activities. It describes the PAGES program Focus 5 “Past Ecosystem Processes and Human-Environment Interactions” that has been designed to use past records to help tackle questions about how future climate will interact with ecosystems and human activities. What are the main types of human activity that have impacted upon ecosystems and continue to do so? How will present interactions between humans and their environment be affected by projected climate change, pollution or population pressure? Which ecosystems within a region are the most sensitive to change? For a given region, can we define more sustainable land use?

Focus 5 promotes and coordinates the analysis of past environmental archives, historical documents and instrumental records through three sub-programs dealing with rivers (LUCIFS), land ecosystems (HITE) and lakes (LIMPACS). Each sub-program has specific objectives and work plans, but all utilize similar or complementary methodologies and techniques to reconstruct past environments. The presentation will show examples of how we can learn from the past. For example, reconstruction of the ‘natural’ states of an environment can be used as ‘targets’ for ecological conservation practices. Reconstructing the variability of ecological processes, such as fire, in ‘pre-impact’ ecosystems allows development of better management strategies, such as for fire suppression.

Past environments often show evidence for the rapid or irreversible changes in processes, such as soil erosion, linked to inappropriate land use. In some previous societies, the level of human impact was sufficient to cause collapse of the fundamental ecological processes that the society depended upon. Focus 5 draws these records together from around the world to in order that we can capitalize on the lessons available from analyzing the past.

The presentation also reviews the priorities for Focus 5 science. One priority is the need to integrate case-studies within different landscapes, ecological regions and mountain zones. Thus, a new organizational matrix for the regionalization of Focus 5 information is presented which will help promote multi- and inter-disciplinary analyses of existing case-studies within regions according to the intensity and duration of past human impact. The new scheme will also help identify other regions for which new research is needed, for example highly valued ecosystems, fragile and degraded landscapes, and human societies threatened by projected climate impacts.

Another priority is the development of mathematical models that can simulate the complex interactions between natural environments, climate and human activities. Reconstruction of past environments provides an unequalled means to test such models so as to provide the confidence that predictive models can be used as tools to help explore the future of people on earth.

Figure1. Human-impacted landscapes in the lake Erhai catchment, Yunnan, SW China. Interconnecting rivers, lakes and agricultural ecosystems within this mountainous landscape are linked to present day environmental issues that include flooding, sedimentation, gully erosion and lake eutrophication. But for how long have these problems existed? Can we detect the legacy of past land use or climate changes? Are the changes in processes accelerating or relatively stable? Which are the most sensitive sub-systems to future climate projections? PAGES Focus 5 is using a combination of sedimentary archives, archaeology, written documents and instrument records to learn from past about the likely effects of climate on these systems in the future and to develop optimum means for their sustainable management (photos: John Dearing).

Figure 2. An example of an organizational scheme for regionalizing PAGES Focus 5 case-studies based on the type of ecosystem or region and the intensity and duration of human land use impact, with examples shown for regions where past records are already available (source: Neil Roberts).