While it may seem that science contributes only marginally to international law, it was in fact a scientist, Garrett Hardin, who proposed a framework four decades ago that illuminates most of the international policy issues of climate change. Hardin’s widely cited 1968 article, “The Tragedy of the Commons,” is much more than a description of the inevitable destruction of public, unregulated, and finite resources, a phenomenon well-known since ancient times. It also offers insights into how one might manage such resources and suggests an ethical approach relevant to the difficult problems of international responses to climate change. Anthropogenic climate change epitomizes the subtitle of Hardin’s article: “The population problem has no technical solution; it requires a fundamental extension of morality.” This subtitle was inspired by an earlier and equally influential article on the control of nuclear weapons by Jerome Wiesner and Herbert York, who admit the limitations of purely scientific or technical modes of thinking in regards to today’s changing world. In other words, the global climate challenge is an intractable international commons issue that requires an international framework through which an economically feasible solution can be created.

The World’s Climate Commons Economy

Before discussing viable solutions, it is first important to establish today’s current climate crisis, which is mainly focused around the energy resource question. Energy is a necessary ingredient of all activity of every kind and can be regarded as the primary physical basis of an economy. The fundamental and pervasive role of energy in the economy virtually guarantees that societies will exploit the least expensive means of producing it in facilities such as stationary power plants or petroleum refineries. These facilities manufacture energy media, such as electricity, gasoline, or hydrogen that are transportable and easily converted to useful work in an endless variety of devices and processes. For nearly two centuries, fossil fuels have been the cheapest source of energy for large-scale economic activity, and their use is growing at an unprecedented pace. However, various market inefficiencies exist that inhibit the most efficient technologies for these end uses. Depending on the perceived benefit from doing so, governments typically intervene through regulation, taxation, or incentives to drive behavior toward greater end-use efficiency.

In the long run, reducing greenhouse gas emissions requires changing the technologies for energy production and use. Reducing or eliminating the need for fossil-fueled energy could be the means through which this long run consequence could be achieved. It is also possible to increase the capacity of the biosphere to absorb CO2 through reforestation and other land-management practices, but this will always be less important than the primary goal of reducing emissions. Because efficient use and CO2-free production of energy are technical matters, it seems logical that the challenge of global climate change should boil down to a question of adjusting the technological basis of the energy economy.

The record of atmospheric chemistry over time hints at the magnitude of this challenge. Atmospheric CO2 began to increase significantly as the Industrial Revolution gathered momentum early in the nineteenth century. Coal was the fuel that freed powered machinery from the constraints of wind or water driven mills. Petroleum and natural gas came later, and much of the energy for today’s world economy—about 85 percent—comes from fossil fuels. The scale of the human behaviors contributing to unwanted atmospheric CO2 is the scale of the world economy. The technologies in question range from large stationary power sources to widely dispersed end-uses in manufacturing, transportation, agriculture, and domestic applications. Most energy use occurs in the context of huge capital-intensive systems that begin with resource extraction and refinement and end with distribution networks. The associated industries are among the largest in any economy, and the sheer physical magnitude of the substances they consume is staggering. The United States alone uses more than 20 million barrels of oil per day, 60 billion cubic feet of natural gas per day, and three million tons of coal per day. This is about a fifth of the world’s energy consumption. Worldwide, coal accounts for about 45 percent of electricity production, natural gas about 24 percent, and nuclear energy about twelve percent. Oil is used mainly for transportation and as a feedstock for the chemical industry.

Most scenarios for future energy production envision a mix of technologies to reduce greenhouse gas emissions. But nearly all the alternatives are substantially more expensive than fossil fuels at current prices, and those that are most competitive (hydroelectric, wind, and solar) have limitations that prevent them from being scaled up to the magnitudes needed to replace the large fossil fuel facilities. At the present time we do not have price-competitive technologies for large scale replacement of fossil fuels. This simple fact is enormously consequential for the international response to climate change. It creates an imperative, for those countries that can afford it, to invest heavily in accelerating the development of scalable CO2-free energy technologies, to provide incentives for reduced end-use energy consumption, and to lower tariffs and licenses on clean energy and energy-efficient technologies that can be used by other countries to reduce global greenhouse gas emissions. For rapidly developing countries, however, of which China is the dramatic exemplar, there is simply no chance that technological solutions will be available in the near future that will allow such development without substantial increases in the production of greenhouse gases. Global CO2 emissions data during the past decade show an accelerating trend and this pattern is likely to persist well into the future.

The Climate Conundrum

Climate change is ultimately a resource sink problem. So is ozone-layer depletion. In both cases the problem is global, the “unwanted byproducts” are relatively well-defined, and they can be traced to rather specific human behaviors whose appropriate adjustment could in principle be substantially managed. A striking feature of the 2002 National Research Council review is how little of it deals explicitly with global climate change, despite its prominence even then as a public issue. The editors of the review acknowledge this asymmetry in their introduction: “Human beings use common-pool resources by harvesting or extracting some of the finite flow of valued goods produced by them or by putting in unwanted byproducts, thus treating the resource as a sink.” Although the use of the common-pool framework to understand sinks seems promising, this line of analysis is not as elaborate or as well studied as that examining resource extraction. What makes the international response to the issues of climate change and ozone depletion so different? The single most important factor is not the scale or seriousness of the impacts—arguably greater for climate change than for ozone depletion. The distinguishing factor is the profound link between the unwanted byproduct, greenhouse gases, and the economies of nations.