Simulation Analysis of Resource Depletion and Climate Change Trends

Aerospace researchers are studying combined climate change models and creating simulation studies to assist the military in planning for future trends and potential world crises.

Climate Model

Michael J. Baxter

U.S. national security is increasingly being threatened by a number of global trends. These include climate change, pollution, resource depletion, global financial imbalances, and forced migration. Researchers at The Aerospace Corporation have combined models of climate change, resources, economics, and population dynamics in a simulation to help the military better anticipate these trends and prepare for potential world crises. Human responses are not necessarily predictable, but the simulation indicates that the synergistic effects of such trends pose significant and possibly dire threats. The ability of the United States to postpone and mitigate these effects is limited and diminishing rapidly—hence the effort to better understand and anticipate them.

Two simulated scenarios

These figures show the results of two simulated scenarios. The first (expected conditions) was specified as a 6°C increase in global average temperature occurring over 100 years using the resource base. The second scenario had the same temperature rise, but energy resources were increased by 75 percent. The top figure shows the resulting conflict map after 25 years using the first scenario.

Expected scenerio

This figure shows total population, population movement, total energy produced, and total rainfall for the next 50 years using the first scenario. The remaining coal, oil, and uranium resources, as well as food and industrial production curves, are also shown.

Expected scenerio 2

This figure shows the same data using the second scenario. The 75 percent increase in energy resources postponed the population decline by roughly four years. The final stable population is roughly the same in both scenarios, as local limits on available resources are only temporarily overcome by trading between cells.

Systems Modeling

Climate models generally consist of systems of differential equations based on physical laws that calculate atmospheric and oceanic attributes such as wind, heat transfer, humidity, and chemistry. These calculations are mapped into three-dimensional grids encompassing Earth’s surface and atmosphere. Researchers at Princeton University generated some of the first long-term climate models in 1969. Those evolving models correlate well with both cur- rent and paleontological observations, although they tend to predict less dramatic effects than were actually recorded or found.

The modeling of global systems involving the dynamic behavior of human beings and the physical world can be traced to Industrial Dynamics, written in 1961. Such models generally involve the use of nodes (sources, sinks, stores, and transfer nodes) and flows of energy and materials. Applications for these models include the U.S. energy transition, energy technology, and policy options aimed at mitigating greenhouse gas emissions; urban policy and environments; transportation and electric utilities; and the interactions between the energy sector and the economy.

In the Aerospace simulation, a dynamic node-and-flow model was superimposed upon a cellular map of the globe. Each cell is a two-degree-latitude by three-degree-longitude area on Earth’s surface. A cell possesses a number of attributes, including the amount of resources that can be extracted from it. Production then determines the energy and materials available to support local populations, water and energy needs, and food and industrial product needs. (see sidebar, An Aerospace Simulation Scenario).

Exchanges of material and energy between cells occur during each interval of time as the model is propagated. As the simulation cycles, shortages may be resolved through trading. When a population does not have the option to trade materials or goods, the unsupportable part of the population may migrate to a surrounding area with sufficient resources to absorb it, decline in place, or migrate to an area with insufficient resources and decline there. Temperature increase is modeled as a function of global atmospheric carbon dioxide concentration that results from energy and resource consumption (primarily oil and coal, but also to a lesser extent operations that support production such as mining and construction). The economic system is modeled as demand and trade of resources and production.

A seasonal hemispheric average temperature variation between 8.1°C during the winter and 22.4°C during the summer, and the corresponding fluctuations in the global rain bands, is the basis for the climate change model. Increased global temperature then drives an increase in the seasonal variation. As the global average temperature increases, the rainfall distributions are distorted. This distortion consists of the narrowing of the equatorial band and movement of the nonequatorial bands toward the poles.

As might be expected, the simulation showed increased conflict in areas already dealing with large and impoverished populations, such as India and Pakistan, and areas that might be directly affected by rising sea levels, such as Indonesia, Northern Europe, and Central America. Perhaps more surprisingly, the simulation also showed conflict within the United States, particularly in the coal-producing states and populations along the Mississippi delta. The simulation also showed a precipitous drop in global energy production with a corresponding drop in total population and a significant shift in migration patterns. (see sidebar, Space Support For Disaster Relief).


A number of implications can be inferred from the results of the simulation. These include a future environment where conflict may be much more widespread than is currently the norm, industrial production and energy for supporting military systems may be increasingly constrained, and migration may become a significant source of conflict and concern. Most of the modeled trends—such as population growth, resource exploitation, and climate changes—follow S-shaped curves in which growth approaches nearly exponential rates until some limiting factor kicks in (sometimes gradually, sometimes abruptly—especially where human ingenuity is involved). The analysis suggests that any solutions or preventive measures for countering the threats would have to be much more fundamental and extensive than those now being applied, and the window of opportunity is much smaller than is generally recognized, because of the nearly exponential nature of the identified trends.

Earth’s climatic system is complex, and significant uncertainty exists in the scientific understanding of it. Continuing research into climatic positive feedback processes and data collection, as well as evaluation of potential interactions with other systems, tends to display greater perturbations than what has been predicted by climate models alone. The integration of climate and global systems models increasingly illustrate the significant national security threats posed by climate change. These models also show the synergistic effects of a number of global trends, including climate change, resource depletion, pollution, and economic imbalances.

Further Reading

M. Baxter, “Scenario Results of a Global Trends Model for Use with Aerospace Systems Combat Simulations,” 2009 IEEE Aerospace Conference, pp. 1–10 (Big Sky, MT, Mar. 7–14, 2009).

British Petroleum Database, (as of Mar. 17, 2011).

K. Deffeyes, Hubbert’s Peak: The Impending World Oil Shortage (Princeton University Press, Princeton, NJ, 2001).

Department of Geosciences, San Francisco State University, (as of Feb. 17, 2011).

R. Doyle, “Greenhouse Follies: Prosperity and Fertility Lie at the Root of Global Warming, But No One Agrees on the Best Fix,” Scientific American, Vol. 286, No. 4 (Apr. 2002).

J. Forrester, Industrial Dynamics (Pegasus Communications, Waltham, MA).

J. Hansen, M. Sato, R. Ruedy, A. Lacis, et al., “Global Warming in the Twenty-First Century: An Alternative Scenario,” Proceedings of the National Academy of Science, Vol. 97, pp. 9875–9880 (2000).

J. Houghton, Global Warming (Cambridge University Press, 2004).

Intergovernmental Panel on Climate Change, Third Assessment Report, Climate Change 2001 (Cambridge University Press, Cambridge, UK, 2001).

J. Lovelock, “The Revenge of Gaia: Earth’s Climate in Crisis and the Fate of Humanity,” (Basic Books, New York, 2006).

N. Oreskes, “Beyond The Ivory Tower: The Scientific Consensus on Climate Change,” Science, Vol. 306, No. 5702, p. 1686 (Dec. 3, 2004).

Spring 2005 Industry Study Final Report: Strategic Materials (The Industrial College of the Armed Forces, National Defense University, Fort McNair, Washington, DC).

United Nations Population Information Network, (as of Feb. 17, 2011).

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