W14: Challenges in Earth System Modelling: Approaches and Applications

organised by Will Steffen, Bob Oglesby, Dave Erickson


Title: Human-induced Land Use Changes: What can Earth System Models Tell Us About Climatic Implications?

Authors: Robert Oglesby, David Erickson, Daniel Irwin, Tom Sever

Abstract: Changes to the landscape have long been thought to have substantial effects on climate, with climatic changes also having impacts on landscapes, For example, changes in climate can lead to changes in vegetation, which in turn induce further changes in climate, and so forth. In addition to these natural processes, however, human-induced changes in land use can also have substantial impacts on climate. A key point here is that the original anthropogenic change may have had nothing whatsoever to do with climate, yet still induce a change in climate that may be detrimental in many ways, and lead to additional changes, both human and natural, in the nature of the landscape. Earth system models, both global and regional, have become valuable tools in understanding and predicting the consequences of specific land use changes on climate. In this paper, Mesoamerica (Central America plus southern Mexico) will be used as a case study. Explored will be the role of the almost complete deforestation in the demise of the Maya civilization about 850 AD, as well as the possible effects on droughts and floods of the present-day extensive deforestation occurring in this region.

Title: Peta-scale climate modeling: Biogeochemical and financial feedbacks

Authors: David Erickson, Robert Oglesby, Scott Elliott, Forrest Hoffman, Forrest Hoffman

Abstract: Several new climate, carbon and biogeochemical modeling results that require multi-Tera flop computational resources will be discussed within the context of climate science and high performance computing. A new fully coupled Earth system model, in both the biogeochemical and physical sense, that specifically tracks CO2 and dimethyl sulfide exchange between the ocean, land and atmosphere systems will be described. As an example of the utility of next generation Earth system models, a series of specific biogeochemical processes and feedbacks in the climate system are examined. A multi-variate clustering algorithm to assess terrestrial ecosystem niche evolution in a warming greenhouse world will be presented. Essentially, the spatial distribution of concurrent changes in temperature, precipitation, radiation and soil moisture drive ecosystem niche evolution in complex and interactive ways. Using climate prediction simulations for 1870-2100, ecosystem niche evolution at mid-high latitudes will be presented. Oceanic applications of this new clustering technique will be explored. Consistent with the theme of fully coupled, comprehensive Earth system model creation, a highly detailed numerical model of energy usage is grafted to a GCM. This energy use and resource allocation model is driven with GCM simulated climate variables from 2000-2025 so as to predict the financial impacts and feedbacks of global warming.

Title: Recent Results From Coupled Climate/Carbon-Cycle Models in CCSM3

Authors: Forrest Hoffman, Inez Fung, W. Mac Post, David Erickson

Abstract: Two terrestrial biogeochemistry modules (CN by Thornton and CASA' by Fung, et al.) have been coupled to the Community Land Model Version 3 (CLM3), the land component model contained in the Community Climate System Model Version 3 (CCSM3). A third terrestrial biogeochemistry module called IBIS (the Integrated Biosphere Simulator) by Foley, et al., has also been coupled to CCSM3 by Mirin, et al., and will be used to further explore land-atmosphere interactions specific to the global carbon cycle within the CCSM framework. A detailed model intercomparison project has been undertaken by the CCSM Biogeochemistry Working Group to elucidate the differences among these biogeochemistry modules in an effort to understand the terrestrial processes important to modeling the carbon cycle in a fully coupled Earth system model. It is expected that this project will result in a terrestrial model for use in future IPCC simulations. Presented will be early results from offline and partially coupled simulations of these terrestrial biogeochemistry modules with and without land cover change, fossil fuel emissions, and ocean carbon flux forcings over the 19th and 20th centuries.