HOLIVAR2006 Abstracts
Climate Modelling of the Holocene: Recent progress and future prospects.
Paul Valdes
University of Bristol, University Road, Bristol, BS8 1SS, UK
Contact: Paul Valdes (p.j.valdes@bristol.ac.uk)
There is now a long history of process-based climate modelling of long term change through the Holocene, during which the complexity of models and complexity of the problems being addressed has gradually advanced. The talk will review the evolution of climate models and their application to long term Holocene climate change.
Initial studies used models which only represented the atmosphere, and had a poor representation of the land surface. These were able to capture some aspects of long term Holocene climate change, but in many cases the simulated changes were considerably smaller than those observed from palaeo-environmental data. This result had a strong influence on the development of climate models, particularly in terms of improving the representation of the land surface and vegetation. The models also now have a detailed treatment of the full 3-D dynamic structure of the ocean. The very latest generation models also include a representation of the ocean and terrestrial carbon cycle, atmospheric chemistry, and dust and other aerosols. These state-of-the-art models are already being used for future climate predictions yet it is essential that they are thoroughly evaluated against the long term Holocene climate change. This is a fundamentally important activity. It ensures that we make maximum use of the available Holocene data and that we fully contribute to the ongoing debate about future change.
The testing of these full complexity models is non-trivial and requires considerable thought and effort. The models are generally global and hence it is essential that we have well understood and well calibrated global synthesis of Holocene climate data. In addition, we must fully understand the uncertainties in the models caused by uncertainties in the forcings and also from within the model physics. This work has been the focus of the Palaeoclimate Model Intercomparison Project (PMIP) and the talk will show many examples of this work.
Finally the talk will conclude with a discussion on the future development in modelling and the exciting new challenges that it will present to Holocene climate scientists.
Paul Valdes' work is focussed on developing a quantitative understanding of the processes that cause natural Earth system change. This enables us to better identify future, human-made change and helps us assess our confidence in predictions of its impacts and significance. This work is done through the use of computer models of the Earth system. Originally his work was focussed on theoretical issues related to the present day atmospheric circulation and future climate change, especially storm tracks and planetary waves. However, this has now developed to include the interactions and feedbacks between the atmosphere, ocean, biosphere, cryosphere, and chemosphere. The work is highly interdisciplinary and the vast majority of publications have been jointly authored.
Current work is focussed on the development and use of the Hadley Centre Climate/Earth System model, and the development of a new generation of fast, intermediate complexity models which will allow us to better investigate the transient response of the Earth System. These tools will open up a whole new range of issues that can now be quantitatively tested. However, it is essential that all such models are thoroughly tested against the present and past Earth system.
After doing an undergraduate degree in Maths and Physics at University College London (1981), and a D.Phil at Oxford University about the atmosphere of Venus (1984), Paul Valdes moved to a postdoctoral position at Reading, with a research theme of idealised studies of storm tracks and large scale waves in the Earth's present and future atmosphere. In 1990, he was appointed a lecturer and in 2000 a Professor in Earth System Science. In July 2003 he took up a position at Bristol University as the Director of the Bristol Research Initiative for the Dynamic Global Environment (BRIDGE).