Let’s credit Senator Lisa Murkowski (R-Alaska) for raising questions in the National Journal about the viability of cap-and-trade versus other approaches for the United States to employ in addressing CO2 and other greenhouse gas emissions linked with global climate change.

Senator Murkowski says that only one approach – cap-and-trade – has received significant attention in the Congress.  Let’s put aside for the moment the fact that most of the 1,428 pages of H.R. 2454 – the American Clean Energy and Security Act of 2009 (otherwise known as the Waxman-Markey bill) – are not about cap-and-trade at all, but about a host of other regulatory approaches (several of which are highly problematic, as I’ve discussed in a previous post).  We can also put aside the fact that both conventional regulatory approaches and carbon taxes have been discussed repeatedly in numerous House and Senate committees over the past decade, and received detailed attention from a succession of U.S. administrations.

So, let’s not quibble about the Senator’s claim that cap-and-trade is the only approach that has received serious attention.  Instead, let’s address the key substantive questions which Senator Murkowski raises, because they are important questions:  Is cap-and-trade the most effective way of addressing climate change?  And are there other approaches capable of achieving the same results at lower cost?  From my perspective, as a card-carrying environmental economist, these are indeed the key questions.

While political leaders in the European Union, Canada, Australia, New Zealand, Japan, and the United States (Congress) move toward cap-and-trade systems as their preferred approach for achieving meaningful reductions in emissions of CO2 and other greenhouse gases, many people – including some of my fellow economists — have been critical of the cap-and-trade approach in the climate context and have endorsed the use of carbon taxes.  The Senator is correct that we should reflect on the merits of that alternative approach.

But, first, what about conventional regulatory approaches, that is, performance standards and technology standards?

Conventional Regulatory Standards

In short, experience has shown that such standards cannot ensure achievement of emissions targets, create problematic unintended consequences, and are very costly for what they achieve.

Why can conventional standard not ensure achievement of reasonable emissions targets?  First, standards typically focus on new emissions sources, and do not address emissions from existing sources.  Think about greenhouse gas standards for new cars and new power plants, for example.  Second, standards cannot possibly address all types of new sources, given the ubiquity of energy generation and use (and hence CO2 emissions) in a modern economy.  Third, emissions depend upon many factors that cannot be addressed by standards, such as:  emissions from existing sources and unregulated new sources; how quickly the existing capital stock is replaced; the growth in the number of new emissions sources; and how intensively emissions-generating plants and equipment are utilized.

Next, what about those unintended consequences?  First, by reducing operating costs, energy-efficiency standards – for example — can cause more intensive use of regulated equipment (for example, air conditioners are run more often), leading to offsetting increases in emissions — the “rebound effect.”  Second, firms and households may delay replacing existing equipment if standards make new equipment more costly.  This is the well-known problem with vintage-differentiated regulations or “New Source Review.”  Third, standards may encourage counterproductive, unintended shifts among regulated activities (for example, from purchasing cars to purchasing SUVs under the CAFE program).  All of these unintended consequences result from the problematic incentives that standards can create, compared with the efficient incentives created by a cap-and-trade system (or a carbon-tax, for that matter).

If you favor a regulatory approach, then you may welcome what’s coming from EPA as a result of the Supreme Court ruling of a few years ago combined with the Administration’s endangerment finding.  For my part, I don’t welcome it; I worry about it, because the set of regulatory approaches that could be forthcoming will accomplish relatively little, do so at an unnecessarily high cost, and hence play into the hands of opponents of progressive climate policy.  (More about that in some other, future post.)

Putting a Price on Carbon

To virtually all participants in the policy world, it has become increasingly clear that the only approach that can do the job and do it cost-effectively is one which involves at its core putting a price on carbon.  That leaves cap-and-trade and carbon taxes.  Let me take these in turn.

Cap-and-Trade

Let’s step back from the debate regarding the details of the Waxman-Markey House bill or the new Senate proposal by Senators Boxer and Kerry, and think about the essence of the cap-and-trade approach.  (For some of those details, however, please see my previous posts, where I have commented on various aspects of Waxman-Markey and described a proposal I developed for The Hamilton Project of an up-stream, economy-wide CO2 cap-and-trade system to cost-effectively achieve meaningful greenhouse gas emissions reductions.)

Here are the basics.  First, aggregate emissions from regulated sources are capped, and the cap is enforced through a requirement for affected firms to hold emissions allowances.  Importantly, allowance trading minimizes costs of meeting the cap.  It does this because allowances migrate to the highest-valued uses, covering emissions that are the most costly to reduce.  So, the emission reductions undertaken are those that are least costly to achieve.  In essence, t
he uniform market price of allowances creates incentives for all covered sources to reduce all emissions, and do so cost-effectively.

A cap-and-trade system can be more environmentally-effective and more cost-effective than standards.  First, in terms of environmental-effectiveness, a cap-and-trade system can ensure achievement of emissions targets.  Cap-and-trade allows policymakers to set specific overall emissions targets.  And a well-enforced system guarantees achievement of those targets, because emissions will not exceed available allowances.  An economy-wide, upstream cap-and-trade system on the carbon content of fossil fuels can cover all fossil-fuel-related CO2 emissions without needing to regulate each emissions source individually.

In terms of cost-effectiveness, a well-designed cap-and-trade system minimizes emission reduction costs.  Unlike NOx, SO2, and other pollutants, GHG emission reductions have the same effect no matter how, where, or when they are achieved.  This makes the climate change problem unique in the degree to which compliance flexibility can be used to lower costs without compromising environmental integrity.  Hence, a cap-and-trade system can minimize costs while still meeting environmental objectives by offering three forms of flexibility: what flexibility; where flexibility; and when flexibility.

In regard to “what flexibility,” many types of actions offer low-cost emission reductions, and a cap-and-trade system allows emission reductions through whatever measures are least costly.  By contrast, standards can target only certain identified emission reduction measures, leaving other cost-effective opportunities untapped.  Furthermore, predictions of what measures are cost-effective may be wrong.

In regard to “where flexibility,” the costs of emission reductions vary widely across industries, across facilities, and even across users of the same equipment.  A cap-and-trade system exploits this variation in costs by achieving reductions wherever they are least costly.  By contrast, standards would only be cost-effective if they accounted for all of the variation in costs across sectors, technologies, and regulated entities — but it is completely infeasible for standards to do this.  Emission reduction costs across sectors and technologies change over time, making the flexibility offered by a cap-and-trade system even more valuable.  Also, lower-cost opportunities to reduce emissions may exist in other countries.  Importantly, a cap-and-trade system creates a common currency (emissions allowances) that makes it possible to link with other systems.

A cap-and-trade system also minimizes costs through “when flexibility.”  Costs can be reduced through flexibility in the timing of emission reductions by avoiding:  premature retirement of capital stock or lock-in of existing technologies; and unnecessarily costly reductions in one year due to unusual circumstances when less-costly offsetting reductions can be achieved in other years.  A cap-and-trade can incorporate “when flexibility”
without compromising cumulative emissions targets through: allowance banking and borrowing; and multi-year compliance periods.

Beyond such “static cost-effectiveness,” cap-and-trade creates incentives for technology innovation, and thereby lowers long-run costs.  By rewarding any means of reducing emissions, a cap-and-trade system provides broad incentives for any innovations that lower the cost of achieving emissions targets.  Although standards may encourage development of lower cost means of meeting the standards’ specific requirements, they do not encourage efforts to exceed those standards.

Several cap-and-trade systems have been successful at achieving environmental goals and cost savings:  the phase-out of leaded gasoline in the 1980s; the phase-out of ozone depleting substances; and the Clean Air Act amendments of 1990 SO2 allowance trading program to cut acid rain by 50%.  Perceived shortcomings in other cap-and-trade systems reflect design choices, not problems with the policy instrument itself.  This applies both to California’s RECLAIM program, and the pilot phase of the EU Emissions Trading Scheme (which is operating successfully in its real, Kyoto phase).

In summary, compared with conventional standards, a cap-and-trade system can be more environmentally-effective and more cost-effective.  As with any policy instrument, however, careful design is important.

Taxing Carbon

As I mentioned, it is clear that the only approach that can do the job and do it cost-effectively is one that involves putting a price on carbon.  So, what about the other carbon-pricing approach — a carbon tax?

I am by no means opposed to the notion of a carbon tax, having written about such approaches for more than twenty years.  Indeed, both cap-and-trade and carbon taxes are good approaches to the problem; they have many similarities, some tradeoffs, and a few key differences.   I am opposed, however, to the confused and misleading straw-man arguments that have sometimes been used against cap-and-trade by carbon-tax proponents.

While there are tradeoffs between these two principal market-based instruments targeting CO2 emissions — a cap-and-trade system and a carbon tax – the best (and most likely) approach for the short to medium term in the United States is a cap-and-trade system.  I say this based on three criteria:  environmental effectiveness, cost effectiveness, and distributional equity.  So, my position is not capitulation to politics.  On the other hand, sound assessments of environmental effectiveness, cost effectiveness, and distributional equity should surely be made in the real-world political context.

The key merits of the cap-and-trade approach I have described above are, first, the program can provide cost-effectiveness, while achieving meaningful reductions in greenhouse gas emissions levels.  Second, it offers an easy means of compensating for the inevitably unequal burdens imposed by a climate policy.  Third, it provides a straightforward means to harmonize with other countries’ climate policies.  Fourth, it avoids the current political aversion in the United States to taxes.  Fifth, it is unlikely to be degraded – in terms of its environmental performance and cost effectiveness – by political forces. And sixth, this approach has a history of successful adoption and implementation in this country over the past two decades.

Having said this, there are some real differences between taxes and cap-and-trade that need to be recognized.  First, environmental effectiveness:  a tax does not guarantee achievement of an emissions target, but it does provides greater certainty regarding costs.  This is a fundamental tradeoff.  Taxes provide automatic temporal flexibility, which needs to be built
into a cap-and-trade system through provision for banking, borrowing, and possibly a cost-containment mechanism.  On the other hand, political economy forces strongly point to less severe targets if carbon taxes are used, rather than cap-and-trade – this is not a tradeoff, and this is why environmental NGOs are opposed to the carbon-tax approach.

In principle, both carbon taxes and cap-and-trade can achieve cost-effective reductions, and – depending upon design — the distributional consequences of the two approaches can be the same.  But the key difference is that political pressures on a carbon tax system will most likely lead to exemptions of sectors and firms, which reduces environmental effectiveness and drives up costs, as some low-cost emission reduction opportunities are left off the table.  But political pressures on a cap-and-trade system lead to different allocations of allowances, which affect distribution, but not environmental effectives, and not cost-effectiveness.

Proponents of carbon taxes worry about the propensity of political processes under a cap-and-trade system to compensate sectors through free allowance allocations, but a carbon tax is sensitive to the same political pressures, and may be expected to succumb in ways that are ultimately more harmful:  reducing environmental achievement and driving up costs.

The Bottom Line

The Hamilton Project staff concluded in an overview paper (which I highly recommend) that a well-designed carbon tax and a well-designed cap-and-trade system would have similar economic effects.  Hence, they said, the two primary questions to use in deciding between them should be:  which is more politically feasible; and which is more likely to be well-designed?

The answer to the first question is obvious; and I have argued here that given real-world political forces, the answer to the second question also favors cap-and-trade.  In other words, it is important to identify and design policy that will be “optimal in Washington,” not just from the perspective of Cambridge, New Haven, or Berkeley.

In “policy heaven,” the optimal instrument to address climate-change emissions may well be a carbon tax (largely because of its simplicity), but in the real world in which policy is developed and implemented, cap-and-trade is the best approach if one is serious about addressing the threat of climate change with meaningful, effective, and cost-effective policies.