Anthropogenic Global Warming: Some First-Order Questions

Today, there’s growing sentiment among members of the U.S. Congress that it must do something to confront the possibility of catastrophic CO2-driven climate change. With this in mind, American corporations have begun taking steps to minimize the adverse financial impact of any actions Congress and the U.S. Environmental Protection Agency might take to address anthropogenic global warming (AGW) – this despite the fact that there continues to be controversy within the scientific community over the degree to which anthropogenic carbon emissions are actually contributing to global warming.

There are several first-order questions about climate change that still lack unique, definitive answers. These include the following:

  • What is the ideal global average temperature?
  • What is the ideal atmospheric CO2 concentration?
  • By what percentage must AGW emissions be reduced to stabilize atmospheric CO2 concentrations?
  • Over what time period must that reduction occur?
  • Who will convince all global emitters to do what must be done?

While these questions may sound trivial, their answers would be crucial to defining any serious effort to halt or reverse global warming caused by anthropogenic carbon emissions, as well as to halt or reverse the accumulation of CO2 in the atmosphere.

WHAT IS THE IDEAL GLOBAL AVERAGE TEMPERATURE?

As you will see in Figure 1, over the past 4,500 years, the global average temperature has hovered around 57 degrees Fahrenheit, plus or minus 2.5 degrees. Since humans have thrived throughout this period, it seems reasonable to assume that the ideal global temperature falls either within or quite close to this range.

Environmentalists, however, have expressed concern that the current rise of approximately 1 degree over the longterm average temperature may be a result of a different mechanism than previous increases. And this in turn, they believe, could drive the average global temperature beyond the recent range … with potentially catastrophic results. There have even been discussions of a “tipping point” beyond which a return to the ideal temperature (or temperature range) might not be possible.

Since the science of global warming is now considered “settled,” it should be possible to definitively identify the ideal global average temperature (or temperature range).

WHAT IS THE IDEAL ATMOSPHERIC CO2 CONCENTRATION?

In 1900, the atmospheric concentration of CO2 was approximately 270 parts per million by volume (ppmv). Since then, the atmospheric concentration of CO2 has increased to approximately 380 ppmv – an increase attributed entirely to the emissions of anthropogenic CO2. In addition, analyses of anthropogenic CO2 emissions since 1900 suggest that not all of the anthropogenic CO2 released into the atmosphere has remained there. Instead, a significant portion has been absorbed (largely by the oceans), thus moderating the increase in atmospheric concentrations. Much of the discussion about a tipping point is built on the fear that progressive increases in temperature will cause the oceans to absorb and hold progressively less incremental CO2 – the key concern being that warmer oceans could stop absorbing incremental CO2 altogether and even release some of the CO2 they currently hold. This in turn would cause the atmospheric CO2 concentration and the average global temperature to increase rapidly and dramatically.

Since both atmospheric CO2 concentration and global average temperature have increased progressively (though not uniformly) over the period, it seems reasonable to assume that the ideal atmospheric CO2 concentration is approximately 270 ppmv. This, however, presents a major challenge since to meet that goal, we would not only have to halt the increase in atmospheric CO2 concentrations but also remove approximately 30 percent of the CO2 currently held in the global atmosphere.

BY WHAT PERCENTAGE MUST ANTHROPOGENIC CO2 EMISSIONS BE REDUCED TO ACHIEVE THE IDEAL?

Studies suggest that the Earth’s oceans absorb approximately one-third of the annual anthropogenic carbon dioxide emissions. Assuming this is true, global anthropogenic CO2 emissions would have to be reduced by at least 66 percent to avoid further accumulation of anthropogenic CO2 in the atmosphere. However, since the absorption of CO2 in the oceans is a function of the CO2 concentration gradient between the atmosphere and the oceans, it would actually take a larger reduction in CO2 emissions to ensure that atmospheric concentrations did not further increase over time. Reducing anthropogenic CO2 emissions to zero would – all other things being equal – prevent further accumulation of CO2 in the atmosphere. However, as mentioned above, if the ideal atmospheric CO2 concentration is approximately 270 ppmv, not only would anthropogenic CO2 emissions have to be totally eliminated but a substantial effort would be required to reduce current atmospheric CO2 concentrations to approximately 270 ppmv.

Although technology exists to remove CO2 from the atmosphere, its application is impractical as long as combustion processes continue to produce additional CO2. Once anthropogenic CO2 emissions were reduced to zero, however, it would be possible to begin reducing atmospheric CO2 concentrations via extraction techniques. Sir Richard Branson has offered a $25 million prize for the development and demonstration of a more economically practical method for removing excess CO2. However, it appears highly unlikely that this would be feasible as long as additional atmospheric carbon dioxide continues to be generated by terrestrial combustion.

OVER WHAT TIME PERIOD MUST THIS REDUCTION OCCUR?

The increase of nearly 110 ppmv in ambient CO2 concentrations over the past century suggests that anthropogenic CO2 emissions would have to be reduced to zero over a period of about 50 years to prevent atmospheric CO2 concentrations from reaching levels of approximately 450 ppmv. Attempting to reduce anthropogenic CO2 emissions to zero over any substantially shorter period would likely result in massive economic dead loss, since many facilities currently emitting CO2 would have to be removed from service before the end of their economic lives. Shortening the time period would also increase the pain and dislocations associated with the massive economic changes involved in the transition.

On the other end of the spectrum, extending the period over which CO2 emissions would be eliminated beyond 50 years would result in a higher maximum atmospheric concentration – making the challenge of removing the excess CO2 even more difficult (an effect that could be offset to some degree by “frontloading” reductions to achieve maximum early impact).

WHO WILL CONVINCE GLOBAL EMITTERS TO DO WHAT’S NECESSARY?

This is by far the most difficult question because unlike the others (which are technical in nature), this one is political. Hinging as it does on the willingness of national leaders to make substantial investments in non-emitting technologies, it raises a number of issues. In some countries, for example, implementing meaningful CO2 emissions controls could mean delaying economic development. The impact of such a transition – particularly in developing economies – would depend on the commercial readiness and relative economics of the non-emitting technologies.

In the case of electric power generation, well-established commercial technology is available to replace existing facilities and meet the growing power needs of developing countries. These technologies include large-scale hydroelectric dams, geothermal and nuclear generation, and solar, wind and small hydro facilities. Keep in mind, however, that the contributions of solar and wind generation are limited by the intermittency of these power sources and the lack of economical, efficient, large-scale electric storage technology.

In the case of transportation, the prospects for carbon control are far less clear. Electric vehicles have an extremely limited range. And while current technology enables synthetic fuels such as ethanol and bio-diesel to be produced in volume, such fuels are still far more expensive than the fossil fuels they would replace. hydrogen also represents a possible “energy carrier” for transportation; however, its conventional production requires huge amounts of electricity, and renewable technologies for hydrogen production are not yet commercially available. In addition, a transition to hydrogen as a vehicle fuel would require the development of an entirely new production, transmission and distribution infrastructure.

SUMMARY AND CONCLUSIONS

The world community’s efforts to stem the increase of anthropogenic CO2 in the atmosphere – and thus bring an end to anthropogenic global warming – have to date been ill conceived and poorly executed. As a global issue, climate change requires a global solution; anything less is doomed to failure. Yet the Kyoto Accords do not represent a global solution, nor would any effort that the U.S. Congress legislated or the Environmental Protection Agency imposed.

A solution to anthropogenic global warming requires definitive answers to the first four questions posed above – answers that would serve as the goals of a global effort to control anthropogenic climate change. Once goals have been established and the technologies required to replace fossil fuel consumption have been evaluated, we would have the basis on which to develop a plan for reducing global CO2 emissions over the required time frame. If such a plan is to succeed, it must be adopted by every nation on the globe, and each nation’s compliance must be documented and verified throughout the reduction time frame.

Based on conservative estimates of the cost of building a nuclear generation infrastructure to replace existing U.S. fossil fuel generation and meet the needs of an expanding U.S. population, I’ve previously estimated that this country would need to invest approximately $10 trillion to achieve a 95 percent reduction in CO2 emissions. That investment requirement, however, could grow to as much as $40 trillion under a business-as-usual legal and regulatory scenario. The global investment required to eliminate anthropogenic carbon emissions would thus be on the order of $40 trillion to $100 trillion by the middle of this century. Keep in mind, however, that these estimates are based on currently available technology. If more advanced technologies were to become available in the power generation, transportation equipment or transportation fuels sectors, those investment requirements could be reduced substantially.

The massive nature and scope of the changes required to achieve zero anthropogenic CO2 emissions globally, combined with the large-scale investments required to achieve such a goal, suggest the need for a massive research, development, demonstration and deployment (RDD&D) effort to develop technologies for executing the plan and achieving its goals with the minimum possible investment and economic disruption. Much of the RDD&D currently being pursued in this regard, however, is not focused on the path to a zero-emissions future – which means that if a zero-emissions future is our true goal, this RDD&D is a waste of time, money and effort because even if successful, it would be inadequate to accomplish the goal. The same can be said of much of the investment currently being allocated or planned to marginally reduce emissions below current levels.

The five questions raised above may seem silly in their simplicity; however, they are fundamental. The absence of unique, definitive answers to those questions at this stage of the discussion of global climate change is both unbelievable and unacceptable. Legislating or regulating on a national basis regarding global climate change, in the absence of unique, definitive answers to these questions, is irresponsible at best and grossly negligent at worst.