Meeting report: TERN ACEAS ‘Unifying principles for terrestrial ecosystem carbon, water and land-surface modelling’
TERN ACEAS organised an invited workshop around ‘Unifying principles for terrestrial ecosystem carbon, water and land-surface modelling’ – in the Rydges Tradewinds Hotelin Cairns from 9-13 April 2013.
The premise of the workshop was that the time has come to reformulate the principles adopted in the development, evaluation and application of models of the terrestrial biosphere. There is a range of such models – some focus mainly on the carbon dynamics of ecosystems, some on water resources, some on the ‘fast’ exchanges of energy, water and carbon between the land and atmosphere (these are the land-surface models that can be coupled to climate models), and some on the slower dynamics of vegetation change in response to a changing environment. However, all deal basically with the same set of processes, and share many common features – as well as common problems. Perhaps the most conspicuous problem is the way models can somehow all represent the present situation quite well, while diverging alarmingly when called upon to predict the future.
The core of the meeting consisted of 1.5 days of presentations (interrupted by many spirited discussions!) and 1.5 days of planning. The topics presented ranged from remote sensing of biomass trends to state-of the-art modelling of Australia’s terrestrial carbon balance. Two common themes emerged. The first was about the design of terrestrial models to include a known set of processes, and the need to make better use of the available data sets for their development, testing and improvement. The second was about the software environment for model development and, especially, the need to improve transparency and modularity. These two themes were addressed in various ways and combinations during subsquent discussions.
The key outcomes were as follows. They embody a determination to build on the remarkable degree of consensus that the meeting revealed.
- A journal article will be written, enumerating a series of new principles for modelling. This will be a radical document. It will propose a decisive break with past practice. It will be developed over the course of a year to allow time to generate a substantive, closely argued, authoritative statement. The writing will be led by Colin Prentice who plans several visits to work with other group members. In addition to statement of principles (the centrepiece), the article will include a system diagram, a Table of ‘knowns’ that should be represented in models, and a list of benchmark data sets that should constitute a minimum set of model evaluation standards.
- A strategy to communicate the Working Group’s major findings will be carried out, exploiting new initiatives under development at several climate modelling centres (including the UK Met Office and the ACCESS group comprising scientists from CSIRO and the Bureau of Meteorology). Colin Prentice and other group members will be arranging strategic meetings in the UK, USA and Australia with the aim to promote a new community approach to land-surface modelling.
The workshop was led by Colin Prentice (Macquarie) and attended by Brad Evans (Macquarie), Vanessa Haverd (CSIRO Marine and Atmospheric Research, Canberra), Trevor Keenan (Harvard, USA), Xu Liang (Pittsburgh, USA), Belinda Medlyn (Macquarie), Natalia Restrepo-Coupe (University of Technology Sydney), Ben Smith (Lund, Sweden), Matt Smith (Microsoft Research, Cambridge, UK), Albert van Dijk (Australian National University, Canberra), Wang Han (Macquarie) and Yingping Wang (CSIRO Marine and Atmospheric Research, Aspendale). A few invitees were not able to join the meeting but have expressed interest in participating in follow-up activities of the Working Group, namely Gab Abramowitz (New South Wales), Damian Barrett (CSIROLand and Water, Canberra), Martyn Clark (NationalCenter for Atmospheric Research, USA) and Sara Mikaloff Fletcher (NIWA, New Zealand).