For many years, there has been a great deal of discussion about carbon-pricing — whether carbon taxes or cap-and-trade — as an essential part of a meaningful national climate policy. It has long been recognized that although carbon-pricing will be necessary, it will not be sufficient. Economists and other policy analysts have noted that policies intended to foster climate-friendly technology research and development (R&D) will also be necessary, but likewise will not be sufficient on their own.

Some recent studies and press accounts, which I reference below, have identified these two approaches to addressing CO2 emissions as substitutes, rather than complements. That is fundamentally inconsistent with decades of research, and so my purpose in this essay is to set the record straight.

Carbon pricing:  necessary but not sufficient

First of all, why is there so much talk among policy analysts and policy makers — not simply among academics — about carbon‑pricing as the core of a meaningful strategy to reduce CO2 emissions? Why, in fact, is this approach so overwhelmingly favored by the analytical community? The answer is simple and surprisingly pragmatic.

First, there is no other feasible approach that can provide meaningful emissions reductions, such as the 80 percent reduction in national CO2 emissions by 2050 that was part of the legislation passed by the U.S. House of Representatives and proposed in the Senate and part of the Obama administration’s conditional pledge under the Copenhagen Accord. Because of the ubiquity and diversity of energy use in a modern economy, conventional regulatory approaches — standards of various kinds — simply cannot do the job. Only carbon pricing — either in the form of carbon taxes or cap-and-trade — can significantly tilt in a climate-friendly direction the millions of decentralized decisions that are made in our economy every day.

Second, carbon-pricing is the least costly approach in the short term, because abatement costs are exceptionally heterogeneous across sources. Only carbon-pricing provides strong incentives that push all sources to control at the same marginal abatement cost, thereby achieving a given aggregate target at the lowest possible cost.

Third, it is the least costly approach in the long term, because it provides incentives for carbon-friendly technological change, which brings down costs over time.

For these reasons, carbon-pricing is a necessary component of a truly meaningful national climate policy. [I’ve written about this in many previous blog posts, including on June 23, 2010, “The Real Options for U.S. Climate Policy.”] However, although it is a necessary policy component, carbon-pricing is not sufficient on its own. This is because there are other market failures that dilute the impacts of price signals on decision makers.

Technology R&D policies:  also necessary, also not sufficient

The most important of these “other market failures” is the public good nature of information. Companies carrying out R&D incur the full costs of their efforts, but they do not capture the full benefits. This is because even with a perfectly-enforced system of intellectual property rights (such as patents), there are tremendous spillover benefits to other firms. Decades of economic research — much of it by my former colleague and coauthor, Adam Jaffe, dean of Arts and Sciences at Brandeis University — has analyzed with empirical (econometric) analysis the remarkable degree to which inventions and innovations by one firm provide valuable information that leads to new inventions and innovations by other firms.

So, firms pay the costs of their R&D, but do not reap all the benefits. The existence of this positive externality of firms’ R&D — or put differently, the public-good nature of the information generated by R&D — means that the private sector will carry out less than the “efficient” amount of R&D of new climate-friendly technologies in response to given carbon prices. Hence, other public policies are needed to address this “R&D market failure.”

New path-breaking technologies will be needed to address climate change, and public support for private-sector or public-sector R&D will be crucial to meet this need. But, at the same time, to address the climate-change market failure itself (that is, the externality associated with greenhouse gas emissions), carbon pricing will be necessary, for all of the reasons I gave above. This is an application of an important and fundamental principle in economics: Two market failures require the use of two policy instruments.

Empirical analyses have repeatedly verified this crucial point — that combining carbon-pricing with R&D support is more cost-effective than adopting either approach alone. Included in this set of studies are the following: Carolyn Fischer (Resources for the Future) and Richard Newell (U.S. Energy Information Administration, on leave from Duke University), “Environmental and Technology Policies for Climate Mitigation“; Stephen Schneider (late of Stanford University) and Lawrence Goulder (Stanford University), “Achieving Low-Cost Emissions Targets“; and Daren Acemoglu (MIT), Philippe Aghion, Leonardo Bursztyn, and David Hemous (Harvard University), “The Environment and Directed Technical Change.”

Complements, not substitutes

An interesting, recent column, “Next Step on Policy for Climate,” by David Leonhardt in The New York Times might give some people the mistaken impression that technology policies are an adequate, even sensible substitute for carbon-pricing. That was not the intended message of the column. In fact, Leonhardt — perhaps the leading economic journalist writing today in the United States ­– indicates clearly in his column that he is skeptical of the notion of thinking of technology subsidies as an adequate substitute for carbon-pricing (in particular, cap-and-trade). And in a follow-up post at The New York TimesEconomix, he makes clear that “these two policies are not mutually exclusive.”

Nevertheless, Leonhardt’s original column (which included a very nice profile of my colleague, Professor Michael Greenstone of MIT) focused attention on a recent report — a report that could give the false impression that technology policies would be a sensible substitute for serious carbon-pricing. The report in question — “Post-Partisan Power” — received significant coverage, primarily because of its sponsorship:  a combination of a prominent Republican-oriented Washington think tank, the American Enterprise Institute (AEI), and an equally prominent Democratic-oriented Washington think tank, the Brooking Institution (and a third partner, the Breakthrough Institute, a California-based environmental think tank).

The report may well garner some bipartisan political support, because it promises a free lunch of painless, win-win solutions, a promise that will resonate with many elected officials. Indeed, the report’s subtitle is “How a limited and direct approach to energy innovation can deliver clean, cheap energy, economic productivity, and national prosperity.” What’s not to like? And the authors are presumably smart and politically shrewd. I know that’s the case with the AEI author, Steven Hayward, who I debated last year in the pages of the Wall Street Journal.

To its credit, the report lays out a menu of policies intended to stimulate carbon-friendly technological change, ranging from $500 million of federal government funding of K-12 curriculum development and teacher training to $25 billion annually of direct federal funding of energy innovation.

For the reasons I explained above (the “R&D market failure” and the “carbon emissions externality”), both direct technology R&D policies and serious carbon-pricing are necessary, but neither is sufficient on its own. Unfortunately, this new report ­­– and some of the press coverage surrounding it — makes the claim that such direct government funding of technology innovation is a sufficient and sensible substitute for meaningful carbon-pricing. That claim is both unfortunate and wrong, as it is supported neither by sound reasoning nor empirical research, as I have described above.

Again, many of the individual technology policy recommendations offered by the AEI-Brookings-BI report are worthy of serious consideration (as a complement, not a substitute for an economy-wide carbon-pricing policy). But the specifics — indeed, much of the meat — are missing. “Reform the nation’s morass of energy subsidies” — yes, but exactly which subsidies (all of which have important political constituencies behind them) will be eliminated? “Recognize the potential for nuclear power” — yes, and both the House and Senate carbon-pricing schemes would have provided tremendous incentives for nuclear power investment.

Overall, there should be concern about how all of this will be funded. Where will the $25 billion per year come from? The report appropriately states that this should not come from general revenues, and thus add to the federal debt. “Phasing out current subsidies for wind, solar, ethanol, and fossil fuels” could be meritorious on its own, but how much does this generate, and does it even pass a political laugh test? Interestingly, beyond this, despite considerable rhetoric about moving beyond debates about carbon-pricing, the report recommends that in order to avoid adding to the federal debt, it would be necessary to impose new taxes, including increased royalties for oil and gas extraction, a tax on imported oil, a tax on electricity sales, and a “very small carbon price” (presumably from a modest carbon tax or unambitious cap-and-trade system).

The actual numbers would be helpful, and the political feasibility remains a serious question. The political challenges that emerged in the effort to pass cap-and-trade climate legislation will not magically disappear if there’s an attempt to induce Congress to approve $25 billion in funding. As Tom Friedman noted on Oct. 12 in The New York Times, Congress has not come close to fully funding the outstanding requests for about $4 billion for ARPA-E (energy) research.

More broadly, despite the attraction of the AEI-Brookings-BI proposal as a potential complement to carbon-pricing (and I am serious that the proposal is of value in that context), one has to be very careful about comparing proposed new policies in idealized form (for example, precisely the right subsidies eliminated and precisely the right new subsidies introduced) with real policies with all their warts (for example, the cap-and-trade bill that was passed by the House last year). Making such comparisons can lead to flawed analysis and misleading results.

This is not a new issue. Robert Hahn and I wrote about this generic problem nearly 20 years ago in an article (“Economic Incentives for Environmental Protection: Integrating Theory and Practice“) which appeared the American Economic Review Papers and Proceedings. At the time, our concern was that this mistake was being made not by the opponents but by t
he supporters of cap-and-trade and other (then essentially untested) market-based instruments. We worried that “many analysts use highly stylized benchmarks for comparison that ignore likely political realities,” and suggested that an appropriate “comparison would be between actual command-and-control policies and either actual trading [cap-and-trade] programs … or a reasonably constrained theoretical … program.”

Likewise today, when carrying out comparisons of policy alternatives, it is fine to compare two theoretical, idealized alternatives, or to compare two real-world policies, but it is problematic and usually misleading to compare a theoretical, idealized policy of one type with a real-world example of another type of policy.

The bottom line

Carbon-pricing — whether carbon taxes or cap-and-trade — will be an essential part of any truly meaningful national climate policy. Likewise, to address the “R&D market failure,” direct technology innovation policies will also be required. Both are necessary. Neither is sufficient. These are complements, not substitutes.


Four years ago, the U.S. Congressional Budget Office (CBO) — widely recognized for its non-partisan, first-rate research — produced a study on the same topic as the AEI-Brookings-BI report, but did so with rigor and without ideology. The CBO report — “Evaluating the Role of Prices and R&D in Reducing Carbon Dioxide Emissions” — was prepared by Dr. Terry Dinan, a long-time, respected CBO economist, and was peer reviewed by an impressive set of academic and other experts. Sadly, the CBO paper received little press coverage, despite its high quality and its relevance. For anyone interested in the topic of this post, particularly those who disagree with my theme, I hope you will read the CBO report.

Also, a reader of this blog post sent me a paper by David Hart and Kadri Kallas (from MIT’s Energy Innovation working paper series) that examines “Alignment and Misalignment of Technology Push and Regulatory Pull.” It’s worth reading in the context of combining carbon pricing and technology R&D policies.