A central message of the latest report from the United Nations’ Intergovernmental Panel on Climate Change (IPCC) is that while the likely effects of climate change are getting scarier, policymakers still haven’t done much to control emissions. In that light we applaud Robert Pollin for grappling with the scale of the effort needed to cut U.S. emissions drastically in the coming decades. Unfortunately, we fear that his plan is mostly a fantasy. Quite apart from its low political prospects, we are concerned about its viability on three fronts.

First is the scope of deployment. Committing 1.2 percent of GDP doesn’t sound like much, but as Pollin says, it is a huge amount of money—by his own calculation, a quadrupling of existing spending on clean energy. We, too, favor a big increase in spending, as does nearly every serious analyst who has looked at this issue. But the short time frame of Pollin’s proposed scale-up almost guarantees that huge amounts of money will be wasted. There are good models for how government can play a constructive role—for example, the Department of Energy’s ARPA-E program—but the current ARPA-E annual budget is only about $300 million, and the entire annual budget for all fundamental energy research at the DOE Office of Science is only about $5 billion. Ramping up these budgets responsibly requires time.

Rapid scale-up almost guarantees that huge amounts of money will be wasted.

Second, Pollin’s analysis is rooted in some magical thinking about technology diffusion. Pollin wants a 40 percent cut in emissions by 2030. In the energy business that seemingly distant date is practically here. The capital stock in energy—power lines, plants, equipment—is long-lived, and planning horizons are long as well. The historical rate of change in the energy infrastructure occurs on a time-scale of fifty to seventy years.

Worse, Pollin’s plan commits a cardinal sin in technology policy: it picks winners and losers. Pollin rejects swaths of technologies, from carbon capture and storage (CCS) to nuclear power. Those technologies do have problems, but at the required scale all options have problems. Pollin champions energy efficiency and renewables, but neither will develop at the speed needed to meet the 2030 deadline. Their ability to contribute the even larger cuts required by 2050 is dubious as well. One of the most aggressive visions for deployment of energy efficiency—a massive McKinsey study published in 2009—projected that efficiency might keep total energy consumption roughly flat. Other credible studies, such as an exhaustive analysis published the same year by the Electric Power Research Institute, are less optimistic about what efficiency can achieve in the short term. The new IPCC report also found that massive deployment of energy efficiency only slowed, rather than flat-lining, the growth in total energy consumption. It also found that, without CCS and nuclear power, the cost of controlling emissions could explode by a factor of four or more.

The policy implications are therefore quite different from what Pollin suggests. Spending on innovation must increase radically, but not faster than the government and industry can effectively absorb the money. And such investments should focus on a diverse portfolio of options, not on handpicked winners. That is the lesson from success with innovation in fracking and horizontal drilling—technologies that have opened vast sources of cheap and less-polluting natural gas. It is also the lesson from government support for solar power R&D around the world. That lesson should be applied to all of the other low-carbon energy sources—including CCS and advanced nuclear energy technologies.

Third, we are concerned about Pollin’s silence on foreign policy. The United States is a big emitter, of course, but it still accounts for only 17 percent of the world’s greenhouse gas emissions. What we do at home matters, but how we multiply our efforts in the rest of the world matters more. Good policy should focus on how domestic action can catalyze comparable action around the world, especially in rapidly growing emerging economies. Reducing worldwide carbon emissions requires coordinated actions with other big countries, including China and the European nations. There is some promise on that front already, such as the U.S.-China clean energy partnership, but much broader efforts are needed.

Solving the challenge of global climate change requires every large nation to invent and deploy totally new energy systems that combine radical increases in efficiency with a host of new supply technologies, many of which don’t yet exist. Policy must recognize the scale of the effort and the speed at which the system can move both here and abroad. Had we started on this task twenty years ago, 40 percent cuts by 2030 might have been feasible. But we didn’t, and they aren’t.