SCIENCE

All of the simulations were run at four different resolutions: 125, 39, 16, and 10 kilometers. For each grid size, the team ran individual 13-month simulations for 48 years (November 1960–December 2007) and continuous 48-year simulations. Furthermore, in an effort to gauge future climate scenarios impacted by CO2, Project Athena simulated the last 30 years of the 20th and 21st centuries, which confirmed some long-held fears.

For example, assuming CO2 levels continue to increase, the model showed definite snow cover decreases at high altitudes, which could lead to droughts in certain parts of the world. It also confirmed the need for more refined models because the outcomes of the higher-resolution models (16-kilometer grid spacing) seemed to be more accurate than those at lower resolutions (125-kilometer grid spacing). As an example Kinter cited the 2003 European heat wave: was it a freak incident or something likely to happen again in the future? The higher-resolution model showed it won’t necessarily become the norm but indicated that it will be much more likely than did the lower-resolution model, and the higher resolution has proven to be more accurate on things that affect European climate, said Kinter.

Team members from COLA, ECMWF, and JAMSTEC/University of Tokyo met in June 2010 at a workshop at ECMWF, said Kinter, and outlined about a half dozen papers to be extracted from the research that they expect to begin appearing in 2011. Furthermore, he said, there has been a large demand for the resulting data, which the team is now working to make public.

“Project Athena also has demonstrated that dedicated supercomputing resources—including the computational capability, data storage, processing, and archival—with the support of a dedicated staff of computer system experts, such as we received from the team at NICS, can greatly increase scientific productivity on large projects. In our case we achieved at least a factor of 4 increase in productivity,” said Kinter.

Ultimately, Project Athena has provided the climate community with a treasure trove of data and laid the foundation for future climate experiments and simulations. The full benefits of the effort have yet to be measured, but there is little doubt that it will be seen as a huge stepping stone on the path to truly understanding Earth’s climate.

“Project Athena has succeeded in showing that increasing the spatial resolution of models of the global climate system to levels that are currently only available for short-term weather forecasting can significantly increase the fidelity of climate simulations,” said Kinter. “Many features of the climate are better represented in high-resolution simulations, including obvious things like tropical cyclones and the distribution of snowfall and not-so-obvious things like the extent, duration, and frequency of drought. The implications of this experiment for how we simulate and predict the climate in the future are very important.”