Climate models

What are Earth System and Climate Models?


Earth system models and climate models are a complex integration of environmental variables used to understand our planet. Earth system models simulate how chemistry, biology, and physical forces work together. These models are similar to but much more comprehensive than global climate models.

To understand Earth system patterns, it is helpful to first understand global climate patterns. Climate is the long-term model of meteorological variables. It includes temperature, rain and snowfall, humidity, sunlight and wind and how they occur over many years. Climate models explain how these variables can change using a physics-based mathematical analysis of how energy, gases and fluids move, combined with measurements taken from experiments, laboratories and other real-world observations.

Earth system models

Earth system models include many interrelated components and processes to help us understand our planet. Credit: Image courtesy of Paul Ullrich, University of California, Davis

Climate models include:

  • The atmosphere, including clouds, aerosols and gases.
  • The earth’s surface and how it is covered by vegetation, snow and ice, lakes and rivers, and soil.
  • The pack ice and the oceans.
  • How all of these components store and move heat and carbon that warm the Earth’s atmosphere.

Global climate models treat the Earth like a giant grid. The size of each grid cell is determined by the power of the computer running the model. Just like a video game, higher resolution requires a much more powerful computer.

Earth system models include all factors of climate models. But as complex as the climate is, it is only part of an even more complex Earth system. The goal of Earth system models is to understand how the Earth works as a system of interdependent parts. These parts include the physical, chemical and biological processes that all interact to shape our planet and the organisms on it. Earth system science is multidisciplinary, drawing on atmospheric science, oceanography, ecosystem ecology, soil microbiology, multi-sectoral analysisand the fundamental scientific disciplines of mathematics, chemistry and physics.

Earth system models can help understand and provide critical information about water availability, drought, climate and temperature extremes, ice caps and sea level, and land use change. lands. They help scientists understand how plants, people, animals, and microbes all contribute to and are affected by Earth’s climate. For example, different plants absorb carbon dioxide at different rates. Different landscapes – ice, oceans, natural vegetation, farmland or cities – can change how the earth absorbs or reflects sunlight. As temperatures and precipitation change, plants respond, altering the balance of atmospheric carbon and radiation. In the ocean, circulation patterns change the amount of plankton and algae.

These factors act on many time scales. The Sahara appears to have gone from wet to dry for thousands to tens of thousands of years. Plants in a humid Sahara absorb sunlight and store carbon, while a dry Sahara reflects sunlight and stores little carbon. These factors also operate on very short timescales, such as the rapid expansion of cities in the 20and century in lands once covered with plants, changing the way the earth reflects and stores heat and carbon. The chemical processes of slowly eroding rock can release dust into the atmosphere, trapping more heat in the air. Short chemical processes such as industrial pollution and soot from forest fires can have similar effects.

Since Earth system models can include the effect of human decisions, they are useful tools for planning things like infrastructure, energy production and use, and landscape use. For example, an earth system model could help a coastal city plan where to build a new highway to ensure that the new highway won’t be flooded if hurricanes become more severe in response to changes in the global climate.

Modeling the whole Earth or the Earth’s climate with enough precision is a challenge for scientists. One solution is to create more powerful computers capable of producing high-resolution models with sophisticated means of representing real-world variables. Another is reduced complexity models. These lower complexity models provide lower resolution climate information, but are easier and faster to run. This makes them ideal for research questions that do not require the detailed data provided by Earth system models. Researchers also use simplified models to quickly test narrow hypotheses about the planet. Researchers can also use multi-sectoral dynamic models explore the interactions and interdependencies between specific human and natural systems.

Fast facts

DOE Office of Science: Contributions to Earth Systems and Climate Models

The Department of Energy’s (DOE) Biological and Environmental Science (BER) Research Program supports Earth systems and climate modeling through several related efforts. The Earth and Environmental Systems Modeling (EESM) program develops and applies models to increase scientific understanding of integrated Earth system factors. He works on research as diverse as infrastructure planning and the development of advanced representations of the Earth. To create the computer codes needed to run complex Earth system and climate models on DOE’s fastest computers, DOE supports the Energy Exascale Earth System Model (E3SM) project through the BER Earth System Model program. Development (ESMD). The E3SM is a massive computer model of the planet designed to run on supercomputers at the DOE’s Leadership Computing Facility. E3SM will provide scientists and decision makers with predictions of Earth system evolution at the spatial resolutions needed to make informed decisions. Finally, DOE’s Regional and Global Modeling Analysis (RGMA) program enhances capabilities for the design and analysis of global and regional Earth system model simulations.