Climate Modeling

Climate models are computer programs utilizing the basic laws of physics and data from atmospheric measurement to predict the development and evolution of regional or global climate. One of the primary aims of modern climate modeling is to investigate the phenomenon of global climate change and to determine to what extent human activity is contributing to global climate change trends.

Data for Climate Models

Climate models are computer programs that use atmospheric and temperature data to calculate the state and development of the climate. Climate models are designed to simulate the fundamental forces of nature, which are based on the laws of physics. These physical laws are translated into differential equations, which can be used to simulate climate variation when supplied with relevant data.

Climate scientists use equations from the study of fluid dynamics to describe the movement and formation of atmospheric fluids and combine that study with input from the chemical reactions involving energetic exchange between the fluids of the atmosphere and the hydrosphere. One of the most basic factors considered when creating a climate model is the exchange of energy between Earth and space.

Solar radiation impacts the Earth, which is the primary source of heat and the main force driving global climate variation. To create climate models, atmospheric scientists must assess the amount of electromagnetic radiation distributed across the Earth from the Sun.

Solar radiation is concentrated in areas where the Sun is directly above the Earth, such as along the equator. High levels of solar radiation heat the land, water, and atmospheric gases and cause low-density pockets to form within the atmosphere. Circulating currents are then formed when high-density pockets of air meet low-density pockets of air. These currents develop into winds and weather patterns and help to distribute solar energy across the Earth. As pockets of air gain and lose density, they also gain and release water vapor in the form of precipitation; this leads to rainfall and snowfall over the terrestrial environment. Climate models also simulate the development of precipitation patterns by creating equations based on relative levels of pressure, solar radiation, and the chemical relationships among atmospheric gases.

Climate models also must consider atmospheric gas levels and their relationship to solar radiation, precipitation formation, and atmospheric gas sources in marine and terrestrial environments. The ozone layer is a thin membrane of gases in the upper atmosphere largely consisting of ozone, a molecule that contains three atoms of oxygen. The ozone layer blocks harmful solar radiation, making ozone concentration an important factor to consider when attempting to model any climate.

Greenhouse gases, such as carbon dioxide and methane, also are important factors in climate models. Concentrations of these gases help to determine how much of the heat that enters the environment from solar radiation remains within the atmosphere and how much of this energy radiates back into space.

Types of Climate Models

One of the most basic types of climate models is the energy balance model (EBM), which simulates the global distribution of radiation and the movement of heat energy from the equator to the poles. This basic type of model is one-dimensional and measures the distribution of energy across the Earth's latitude by measuring the surface temperature.

Another basic one-dimensional model is the radiative-convective model (RCM), which measures the distribution of energy through convection, which is measured by the heat distributed through a vertical column of air. RCMs ignore the horizontal distribution of heat across the Earth’s surface and focus on the heat gradient within the vertical dimension of the atmosphere. RCM models are useful for measuring the effect of increased greenhouse gases on vertical heat distribution; they are most effective when measuring climate variation in regional areas.

RCM and EBM models help calculate climate change in regional areas, but they are not sufficient for effectively predicting global climate change. By combining the data from RCM and EBM models, atmospheric scientists create statistical dynamical models (SDMs), useful for modeling the development of weather patterns and storm systems. For instance, SDMs, which are used to predict the development of tropical cyclones, take into account changes in pressure, humidity, and wind currents and often use data from one-dimensional RCM and EBM systems.

General circulation models (GCMs) are three-dimensional models that track climate change in the three basic dimensions and through time. Generally, GCMs are designed to measure climate in either marine or terrestrial ecosystems. These two models can be combined to form an atmospheric and oceanic general circulation model (AOCGM), the basis of most modern climate modeling programs.

AOGCMs are important for modeling global changes in temperature, precipitation patterns, and other general patterns but lack the accuracy needed for modeling specific changes in regional climate. For this reason, atmospheric scientists still use limited models, such as RCMs and EBMs, to study localized climate variation and then use these data to create AOGCM systems.

Other climate models and models that use a combination of modeling data exist. Intermediate Complexity Models include increased detail regarding geographical features. Simple Radiative-Convective Models expand EBM models and Coupled Atmosphere-Ocean-Sea Ice Models look at the mass transfer, energy transfer, and radiative exchange between the atmosphere, ocean, and sea ice.

Applications of Climate Models

Many researchers studying climate change are involved in the ongoing debate over global climate change, specifically the degree to which human activity and environmental modification contribute to the warming trends. GCMs and AOGCMs are helping scientists understand the significance of current data regarding climate change.

Many of the causal and contributing factors involved in climate change are poorly understood. GCMs and other climate models can help scientists understand how factors including increases in greenhouse gas emissions, atmospheric ozone concentrations, and deforestation contribute to climate change. By refining climate models, researchers also hope to discover unknown elements that might influence them.

Climate models also predict weather patterns. Regional climate modeling, for instance, can allow scientists to predict the development of tropical storms and other weather systems that may threaten human settlements. Computer-generated climate models have refined warning and alert systems that help protect communities from potential storms and other weather-related threats.

Climate models are used primarily to study the interaction between humans and climate change, but they are also useful in ecological research. They help ecologists and biologists understand the relationship between nonhuman animals and climate change. These data help researchers create systems that can be used to preserve and protect wildlife and ecosystems from climate variation.

Climate Modeling Organizations and Groups

The National Aeronautics and Space Administration (NASA) conducts climate modeling research through its Goddard Institute for Space Studies (GISS). Researchers at GISS use RCM, EBM, and SDM systems for regional and localized analyses and also develop detailed GCM calculations to study individual variations within oceanic and terrestrial systems. Data from these localized systems are integrated to create AOGCM models using the most advanced technology available from international participants.

The GISS climate modeling system's primary interest is investigating human activity's impact on climate change, including the emission of greenhouse gases and deforestation. GISS research focuses on climate sensitivity, which attempts to measure the climatological response to various perturbations, such as local or widespread increases in gas emissions or other similar variables. GISS researchers also help develop GCM models that other organizations use to conduct climate research. In this capacity, GISS works on parameterization, which sets parameters for the various inputs used in calculating climate variation and development.

The Atmosphere-Ocean Dynamics Group (AODG) of Cambridge University’s Department of Applied Mathematics and Theoretical Physics conducts many climate modeling programs utilizing GCM and AOGCM models and uses many regional climate models. Cambridge researchers focus on fluid dynamics, including the movements of atmospheric gases and water in the oceans and precipitation systems.

One of the AODG’s primary ongoing programs is calculating ocean turbulence and its effect on climatic patterns. Other research programs at the university study global fluid dynamics of the atmosphere as a whole, using AOGCM data and regional data to study the mathematical principles behind fluid exchange in planetary atmospheres.

The Met Office Hadley Centre is one of the most prominent organizations for climate change research in the United Kingdom (UK). It is funded by the UK Department of Energy and Climate Change and the Department of Environment, Food, and Rural Affairs. The Hadley Centre focuses on creating programs aimed at modeling the Earth's climate from the twentieth century and utilizing this information to create detailed models predicting climate development in the twenty-first century. Researchers use a variety of GCM and AOGCM programs to complete their climate models and have been leading contributors to data used in government policy meetings regarding global climate change.

The World Climate Research Programme (WCRP), under the leadership of the International Council for Science, is one of the largest global organizations contributing to research on climate modeling systems. The WCRP funds and coordinates research programs with meteorological organizations, universities, and professional research organizations studying climate change and creating new systems and methods for climate modeling technology. The WCRP is interested in investigating the fundamental processes governing climate development and studying human interaction with the climate and the effects of human activity on climate change. Many research programs sponsored or conducted by WCRP members focus on global warming and human activity.

Principal Terms

carbon dioxide: a gaseous combination of carbon and oxygen that functions as one of the most important greenhouse gases

climatology: branch of science that studies climate and climate change and chemical and physical forces within the atmosphere

convection: patterns of molecular movement within liquids generally related to heat

deforestation: removal of forest areas or stands of trees, including for commercial and agricultural development

fluid dynamics: branch of physics that deals with the movement of fluids, including gases and liquids

general circulation model: climate model that measures variations across three dimensions

ozone: gaseous compound composed of molecules containing three atoms of oxygen bonded together

parameterization: the process of setting parameters for a measurement or other analysis system

precipitation: the process by which atmospheric water vapor condenses and returns to Earth

Bibliography

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