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What is climate change?

Since the Industrial Revolution, Earth has warmed measurably. The increasing presence of carbon dioxide in the atmosphere causes it to heat up. Beyond changes in day-to-day weather, climate change refers to a long-term trend in the carbon cycle, energy exchange, oceanic currents, and other terrestrial processes. Accordingly, the Department of Energy (DOE) seeks to understand and mitigate climate change.

What is LLNL doing to address climate change?

At Lawrence Livermore, numerical models running on high-performance computers are a vital part of research in many programs. Even in the Laboratory’s early days, researchers understood that the same computational approaches for simulating nuclear weapons could be applied to better simulate evolution of the weather and for applications such as tracking releases of radioactive and other hazardous materials.

Since the early studies, modeling capabilities have advanced along with the power of the computers themselves, and Livermore scientists subsequently addressed issues such as the effects of atmospheric nuclear tests, atmospheric ozone, nuclear winter, and the fallout from nuclear and other toxic-material accidents.

Today, LLNL researchers continue to lead local and international efforts to model, evaluate, and predict climate change. The computational intensity of these models helps drive the development of more and more powerful computers, software, and data management, which in turn benefits Livermore’s stockpile stewardship and other security missions.

The DOE and worldwide climate science community rely on Livermore scientists’ expertise, supercomputing facilities, and advanced simulation and analysis capabilities to carry out this important research.

How does predicting the weather differ from predicting the climate?

Across the planet, temperatures, wind cycles, pressure systems, and atmospheric conditions such as varying amounts of sunlight, cloud cover, and precipitation create Earth’s weather. An area’s climate is defined by its prevailing weather conditions over long periods of time.

When predicting the weather, meteorologists typically use results of several weather models combined with their expertise to provide a forecast, usually for the week. This process is called deterministic forecasting, and after a few days or weeks, one would know if the forecast was correct.

Unlike weather forecasts, which describe a detailed picture of the expected daily sequence of conditions starting from the present, climate models are probabilistic, indicating areas with higher chances to be warmer or cooler and wetter or drier than usual. Climate models are based on global patterns in the ocean and atmosphere, and records of the types of weather that occurred under similar patterns in the past.

Learn more: What’s the difference between climate and weather?

What types of climate models does LLNL help develop?

Global climate models (also known as general circulation models) calculate the interactions between the ocean, atmosphere, sea ice, and land surface using factors such as water vapor, carbon dioxide, heat, and the Earth’s rotation as input. The result is a three-dimensional view of the time evolution of the state of the whole climate system.

Global cloud-resolving models (GCRMs) are a newer type of general circulation model. GCRMs can resolve multi-scale atmospheric processes from cloud-scale to planetary-scale while conventional global models can only cover from synoptic-scale to planetary-scale. (Synoptic scale refers to weather features that range in size from 1,000 to 10,000 kilometers.)

Earth system models (ESMs) simulate how chemistry, biology, and physical forces work together. These models are similar to but much more comprehensive than global climate models. ESMs can run as small-scale models that operate in a limited area and focus on regional phenomena. They can also be large-scale models representing predicted conditions over the whole Earth.

Learn more:

• DOE Explains...Earth System and Climate Models
• Basics of Global Climate Models
• Climate models

How long has LLNL worked on climate research?

LLNL has a proud history of leadership in advanced atmospheric and Earth system modeling.

• 1958
  

  Building on simulations of nuclear fallout effects on the atmosphere, LLNL kicks off climate studies with the first global general circulation model. It calculated temperature, winds, humidity, clouds, precipitation, the day-and-night cycle, and weather systems around the globe.
• 1972
  

  After more than a decade of technological improvement in three-dimensional atmospheric simulation codes combined with rising environmental concerns, the Atmospheric Sciences Division forms at LLNL.
• 1983
  

  Tracking global precipitation patterns and land‒atmosphere feedback leads to collaborations that explore, for instance, the potential effect of nuclear war on the regional and global climate.
• 1989
  

  To encourage systematic and comprehensive evaluation of global climate models, the Program for Climate Model Diagnosis and Intercomparison is created to develop tools for diagnosing, validating, and comparing models that predict climate change.
• 1995
  

  The second Assessment Report from the Intergovernmental Panel on Climate Change (IPCC) concludes that “the balance of evidence suggests a discernible human influence on global climate.” IPCC regularly relies on LLNL scientists as lead authors.
• 1999
  

  LLNL establishes the Earth System Grid Federation (ESGF) to enable international climate simulations and data exchange, including Community Data Analysis Tools and data management for the Coupled Model Intercomparison Project. ESGF has since been recognized with a prestigious R&D 100 Award.
• 2000
  

  LLNL embarks on twenty-first century climate studies by leveraging supercomputers and breaking ground in areas such as the global carbon cycle, cloud processes, stratospheric ozone, and sea-level rise. Other ongoing research includes greenhouse-gas capture and sequestration science.
• 2007
  

  Bolstered by LLNL scientists contributions, the IPCC shares the Nobel Peace Prize with former Vice President Al Gore for work associated with anthropogenic (human-influenced) climate change.
• 2013
  

  Leading the DOE’s Energy Exascale Earth System Model project, LLNL investigates complex processes such as evolution of the water cycle and precipitation, greenhouse gas fluctuations, and long-term effects of the Antarctic ice sheet.
• Today
  

  LLNL is developing simulations at the spatial and temporal scales needed by decision-makers to anticipate and mitigate the impacts of climate change on critical infrastructure and national security.