Develop improved and more comprehensive Earth System Models
Background
GFDL has been developing climate models for more than 50 years. See http://www.gfdl.noaa.gov/climate-modeling for more details on the development of the physical climate models. Here the focus is on the development of Earth System Models.
Earth System Models
For the past several years, GFDL has been working to close the carbon cycle in one of its state-of-the-art physical climate models (CM2.1, see Delworth et al., 2006). This type of model is called an Earth System Model or ESM. It includes all the components of the physical climate model and adds components to simulate bio-geo-chemistry on the land and in the ocean (see figure).
At GFDL, a new team was formed to perform this new model development task. This new team includes both federal and Princeton University personnel. It took several years of additional work to incorporate the new state-of-the-art ESM components in our existing, successful physical climate model. Two new ESMs are being used in the CMIP5 project (http://pcmdi-cmip.llnl.gov/index.html). Our new ESMs are being used by the AR5 authors and by us at GFDL for the assessment of climate and ecosystem changes. Important questions such as the magnitude of human impact on the atmospheric CO2 concentration, carbon fluxes due to land use changes and ocean acidification are being investigated using ESM simulations.
Figure: Major natural and anthropogenic processes and influences on the climate
system addressed in scenarios
The climate system consists of five interacting components: the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere. Scenarios of emissions and other drivers are used to assess the impact of a range of human activities on these components. Changes in climate described in climate scenarios are major drivers of changes in both natural and human systems. Impacts on ecosystems, natural resources, economic activities and infrastructure, and human well-being, depend not only on climate change, but also on other changes in the environment (depicted in environmental scenarios) and the capacity of societies and economies to buffer and adapt to impacts (addressed in scenarios of vulnerability and adaptive capacity). Closer integration of scenarios is required to address feedback loops and other issues, such as the ecological and economic implications of different sets of adaptation and mitigation policies. Figure from U.S. Climate Change Science Program. Strategic Plan for the Climate Change Science Program, Final Report (eds Subcommittee on Global Change Research) Figure 2.5 19 (US Climate Change Science Program, Washington DC, 2003).