Vision and Mission

In 2013, the US Department of Energy developed a report summarizing observed long-term trends that, if continued for several decades, would have major impacts on the energy sector (DOE, 2013). Among these were regional trends in air and water temperatures, water availability, storms and heavy precipitation, coastal flooding and sea-level rise⎯trends that are now all too evident. Concurrently, DOE developed the Exascale Initiative, “a major computer and computational science initiative anchored in (DOE’s) mission challenges…. to capture the successful transition to the next era of computing in the 2020 timeframe”, while noting that “due to projected technology constraints, current approaches to HPC software and hardware design will not be sufficient to produce the required exascale capabilities.”1 Our overarching strategy has changed little since our last proposal in 2018, although our approaches have necessarily evolved with the scientific and computational landscapes of DOE and the broader community. The E3SM project, represented schematically in Figure 1, was conceived from the confluence of mission need and the imperative to adapt to new paradigms in scientific computing technology, as motivated by the aforementioned reports. Developed as an ongoing, state-of-the-science Earth system modeling, simulation, and prediction project, it aims to optimize the use of DOE laboratory resources to meet the science needs of the nation and the mission needs of DOE for Earth system prediction. Laboratory resources include the people, programs, and facilities, current and future. They collectively represent a unique combination of scientific and engineering expertise as well as leadership computing and information technologies required to construct, maintain, and advance an Earth system modeling capability that is needed by DOE.

Figure 1. The E3SM Mission: Use exascale computing to carry out high-resolution Earth system modeling of natural, managed and man-made systems, to answer pressing problems for the DOE*.

The Energy Exascale Earth System Model (E3SM) Project has reached an exciting juncture. The project is on the verge of  achieving its original ten-year goal articulated in 2014: build a world-class Earth system model for the US Department of Energy (DOE) applications on Exascale computation platforms. It is evolving now to deliver Human-Earth system projections with actionable science results that are urgently needed in a rapidly changing climate.

Building on progress made during Phases 1 and 2 between 2014 and 2022, the project identified the following priorities for Phase 3 (2023-2025) to achieve its original long-term goal and to lay the foundation for further development of transformative modeling capabilities for the next 10 years:

• Improve the scientific accuracy of the E3SM coupled system model through substantial reduction of large and persistent biases.
• Undertake new developments necessary to add the capabilities required to address the science questions for E3SM v3 and to lay the foundation for developing our next generation modeling capabilities.
• Execute major simulation campaigns to address the science questions driving the development of E3SM v3.
• Accelerate the production use of pre-Exascale and Exascale hybrid central processing unit (CPU) – graphics processing unit (GPU) systems (also called GPU-enabled, or simply GPU hereinafter) at Office of Science (DOE/SC) Leadership Computing Facilities (LCFs).
• Enable the broader use and extensible development of the E3SM model by DOE-funded scientists and incorporate major model developments and improvements from DOE/SC-supported projects that have demonstrated potential to improve the modeling system scientifically or computationally.

Addressing our grand challenge requires a three-pronged strategy of sustained advancement to overcome three major limitations: 

• Pushing the high-resolution frontier of Earth system modeling. E3SM will remove the computational barriers to production-scale, high-resolution Earth system simulations and projections through a combination of strategic model development and computational advances targeting exascale computers and beyond. Although other modeling centers have similar science objectives, E3SM uniquely integrates model development with leading-edge computational advances for a sustainable path toward ultra-high-resolution modeling with throughput for coupled Earth system simulations. 
• Bridging the gap in scales and processes. The E3SM modeling system includes natural, managed, and man-made systems for a new class of models that bridge the gaps in scales and processes common in traditional Earth system models to address energy sector vulnerability to climate variability and change. 
• Quantify uncertainty with ensemble modeling. Increasing model resolution and complexity is important for improving model fidelity, but Earth system projections are challenged by large uncertainty associated with the system’s internal variability and the model’s parametric uncertainty. To provide actionable projections, E3SM will develop computational strategies for ensemble high-resolution simulations. 

As the project enters its third phase (E3SM Phase 3), it is well positioned to achieve many of its original long-term objectives and define new goals for the next decade. For example, pushing past exascale will require ever-more disruptive approaches such as edge computing, machine learning (ML), and next-generation artificial intelligence (AI) to accelerate the fusion of observations and measurements with computing. By continuously integrating advanced technologies and climate science to deliver capabilities for multi-resolution modeling of the human–Earth system, the 2023 E3SM model will be at the center of a connected scientific ecosystem for understanding and modeling the Earth system. DOE will lead in actionable projections of human–Earth system evolution across a broad range of time and spatial scales to support multi-sectoral decision making and DOE’s energy mission.