Legal disputes related to climate change will continue for a century.

• Author: Pierce, Richard J., Jr.

1. INTRODUCTION TO THE PROBLEM

   I am confident that my current students will be working on legal issues related to climate change until they retire fifty years from now.

   The average global temperature is already certain to increase by 2[degrees]F. (1) It will increase by far more, with other major attendant changes in climate, unless we reduce global emissions of greenhouse gases (GHGs) by at least 50% by 2050. (2) The effects of failing to accomplish that daunting task will be catastrophic. They include the deaths of millions and the displacement of scores of millions. (3) The worst effects will be experienced in places like India and Africa, which will suffer extreme desertification, and in many island states as well as coastal Indonesia and large portions of Bangladesh, which will be underwater. (4) The U.S. will also suffer some significant adverse effects, including desertification of much of the southwest, submersion of significant coastal areas, increases in the incidence and severity of storms of various types, (5) and a 12[degrees] increase in the average summer temperature in Washington, D.C. (6)

   The task of effectively mitigating climate change is somewhere between extremely difficult and impossible. The main problem is carbon dioxide (C[O.sub.2]) emissions. C[O.sub.2] is by far the most abundant GHG, and it is the inevitable byproduct of hydrocarbon combustion. (7)

   While the U.S. is the second largest source of C[O.sub.2], neither the U.S. nor the developed world have accounted for any significant increase in emissions in several years. (8) Even if it were to take no steps to reduce C[O.sub.2] emissions, the developed world is unlikely to increase emissions of GHGs by any significant amount in the future because of the steady improvements in energy efficiency that always occur over time. The increases in C[O.sub.2] emissions over the last few years and in the future will occur almost exclusively in the developing world, with China alone accounting for a majority of the increase.

   This trend is easy to explain. The citizens of the developing world want the kinds of goods and services that we have long taken for granted, such as cars and air conditioning, for example. As they become increasingly able to indulge those preferences, they will increase their per capita emissions of C[O.sub.2].

   Reducing C[O.sub.2] emissions in the developed world by 50% would not be nearly enough to accomplish the goal of reducing global emissions by 50%. The developed world must reduce its emissions by far more than 50% to offset the inevitable increases in emissions in the developing world. That task is made more difficult by the basic laws of supply and demand. Most hydrocarbons are sold on global markets. To the extent that the developed world is successful in reducing C[O.sub.2] emissions through some means--for example, a carbon tax or subsidies for carbon-free sources of energy--the attendant reduction in the quantity of hydrocarbons demanded will decrease the global price of hydrocarbons. That, in turn, will increase consumption of hydrocarbons in the developing world, unless developing countries also adopt means of reducing this consumption--a step they have not been willing to take to date. The resulting increase in consumption of hydrocarbons in developing countries has the potential to offset 29%-70% of the reductions in hydrocarbon consumption in the developed world. (10) Thus, countries in the developed world need to reduce C[O.sub.2] emissions by far more than 50% even if countries in the developing world can be persuaded to take steps to reduce the otherwise dramatic increase in their C[O.sub.2] emissions.

   While the broad outlines of the relationship between C[O.sub.2] emissions and climate change are well known, there is at least one major source of uncertainty. We do not have a good understanding of the shape of the doseresponse curve that describes the relationship. Thus, for instance, some climate scientists believe that there is a "tipping point" at which a given concentration of COs in the upper atmosphere will have irreversible catastrophic effects on climate. (11) Others believe that the dose-response curve is roughly linear, thereby creating a situation in which each increment of C[O.sub.2] will have a roughly proportionate adverse effect on the climate. (12)

   That difference could be important for policy-making purposes. If the relationship is characterized by a "tipping point," and we conclude that we cannot avoid exceeding that point, we should simply accept the inevitable changes in climate and put all of our scarce resources into devising and implementing methods of adapting to the changes in climate. If the dose-response curve is linear, we should devote significant resources to reducing global emissions of C[O.sub.2] whether or not we believe that we can avoid a particular concentration of C[O.sub.2] in the atmosphere. In that situation, we should act on the basis of a belief that every incremental reduction is important.

   The Supreme Court majority in Massachusetts v. U.S. Environmental Protection Agency (Massachusetts v. EPA) (13) implicitly embraced the assumption that there is a linear dose-response relationship between GHG emissions and climate change. EPA argued that it was not required to regulate emissions of COs from new cars in part because any such effort was unlikely to have any meaningful beneficial effect on climate change) (4) Total emissions of C[O.sub.2] from the U.S. transportation sector accounts for only 5% of global emissions of GHGs. (15) Moreover, even a large reduction in emissions from new cars sold in the U.S. would have little effect on climate change, given the large offsetting increases in C[O.sub.2] emissions in developing countries. The majority rejected EPA's argument on the basis that regulating C[O.sub.2] emissions from new cars in the U.S. would make a "meaningful contribution" to climate change mitigation. (16)

   I will indulge the assumption that the dose-response curve is linear in the balance of these Remarks, but it is merely an assumption. I do not have enough relevant expertise to participate in the debate between the proponents of the "tipping point" theory and those who believe instead that the relationship between GHG emissions and climate change is linear.

2. IMPEDIMENTS TO CLIMATE CHANGE MITIGATION

   The main impediments to effective climate change mitigation are economic and political. Hydrocarbons are much less expensive than carbonfree alternative sources of energy. I will focus primarily on the electricity sector, which accounts for nearly half of C[O.sub.2] emissions in the U.S., (17) but the economic and political impediments are similar in the transportation and industrial sectors. (18)

   The most recent estimates of the cost of generating electricity from various sources in the U.S. are: coal, 10 cents per kwh; gas, 8cents per kwh; wind, 15cents per kwh; nuclear, 12cents-19cents per kwh; and solar, 15cents-40cents per kwh. (19) The cost differences between hydrocarbons and carbon-free sources are less in Europe and Asia, because coal and gas are more expensive in Europe and Asia than they are in North America. (20)

   Those are estimates of generating costs only, however. Supplying electricity from wind and solar to consumers is more costly than supplying electricity from gas or coal for two reasons that are independent of generating costs. First, the unit cost of transmission is higher, partly because those sources tend to be long distances from major markets and partly because they are much lower load factor sources. (21) Second, both wind and solar are intermittent sources. To compare the cost of intermittent sources with the cost of dispatchable generation sources like coal, gas, and nuclear, the cost of some combination of supplemental dispatchable sources and storage must be added together, or the value of each unit of intermittent energy must be discounted to reflect its lower value. (22) Both adjustments add significantly to the effective unit cost of supplying electricity generated by wind or solar to consumers. (23) To illustrate the effect of those adjustments, consider that the unit cost of the Cape Wind project proposed to be constructed off of Cape Cod will be 83.2cents per kwh after adjusting for the lower value of the intermittent supply. (24)

   A similar adjustment must be made to reflect the lower value of the intermittent supplies of electricity available from solar sources, but the adjustment is lower because the correlation between periods of high electricity demand and periods of sunshine is better than the correlation between periods of high demand and periods of wind velocity sufficient to operate windmills. (25) When unit-generating costs are adjusted to reflect differential transmission costs and intermittency, solar and wind are three to fifteen times more expensive than coal or gas in the U.S. (26)

   The political impediments to effective climate change mitigation are primarily derivative of the economic impediments. Four other factors add to these political impediments, however. First, because C[o.sub.2] remains in the atmosphere for many decades after it is emitted, the cost of implementing mitigation measures must be incurred many decades before the benefits will be experienced. Second, the benefits will appear in a form that many people either do not understand or do not accept. They will take the form of a negative: catastrophic climate effects that will be avoided. Third, the benefits will be enjoyed disproportionately by citizens of highly vulnerable, developing countries like India and Bangladesh, while the costs will be incurred disproportionately by citizens of less vulnerable developed countries like the U.S. and Germany. Indeed, many people In countries like Canada and Norway may experience net benefits as a result of climate change. (27) Fourth, most of the projects that must be completed as part...