The aim of my research is to develop a policy approach capable of achieving the IPCC target while also increasing broadly shared economic well-being, starting with the expansion of job opportunities. I am fully aware that any clean energy project that sacrifices good jobs will face formidable political resistance, unacceptably delaying effective climate stabilization policies. But I am encouraged that none of the respondents suggests that achieving the IPCC target must make life more difficult for American workers.

My coauthors and I address many of the specific points the respondents raise in two book-length studies, one with the Center for American Progress (CAP), focused on the United States, and another, forthcoming from the United Nations Industrial Development Project (UNIDO), on the global economic dimension. Indeed I agree with most of the respondents in both spirit and detail. I will briefly comment on areas of agreement, address more significant disagreements, and conclude by looking to the larger global implications of clean energy policy.

First, I fully support Reed Hundt’s call for private investments and innovative financing initiatives such as the Connecticut Green Bank. I also endorse Sanya Carley’s call for net metering and feed-in tariffs, which have been critical to the expansion of clean energy capacity in several European countries. Mara Prentiss raises important points on the successful trajectory of energy efficiency over the past forty years and on the promise of even better technologies that will reduce the enormous amounts of energy we waste.

Implementing this clean energy program will be a challenge, but it is hardly a fantasy.

Madeline Janis is right that community and regional development projects should complement a “superfund for workers.” She is also right that new jobs in the expanding clean energy sectors must meet high standards in wages, workplace conditions, and opportunities for women and minorities. But even though some workers will need additional training, clean energy investments will mainly generate jobs in the same areas of employment—manufacturing, construction, agriculture—in which people already work. While we cannot neglect the challenges of matching workers to skilled jobs, we also should not exaggerate them.

Now to deeper disagreements. Leslie Dewan claims that nuclear energy can be both cheap and safe. The U.S. Energy Information Agency, however, estimates that the average cost of generating electricity from nuclear power in 2017 will be 11.4 cents per kilowatt hour, 14 percent higher than geothermal, 16 percent higher than wind, and 25 percent higher than hydro power. These projections follow a half-century of massive government support for the development of nuclear power. Dewan also inadvertently undermines her own case for nuclear safety. She writes that with newly developing technology the radioactive lifetime of nuclear waste could possibly last for “only hundreds of years.” She also neglects entirely the fundamental security concerns posed by scaling up nuclear technologies throughout the world.

George Tynan and David Victor believe that new fracking technology is attractive because it has “opened vast sources of cheap and less-polluting natural gas.” But even though carbon emissions from natural gas are roughly half those from coal, natural gas is not a clean energy source. In our CAP study, we offer the following scenario. Assume that all of the Obama administration’s energy efficiency and renewables initiatives are fully implemented. Also assume that coal consumption falls to zero, with natural gas consumption covering the difference entirely. Even under these implausibly optimistic assumptions—and setting aside the environmental issues associated with fracking—U.S. emissions after twenty years would still be nearly 30 percent above the IPCC target.

Tynan and Victor say my proposals are based on “fantasy” and “magical thinking.” But if the program I propose were successfully implemented, U.S. per capita emissions in twenty years would still be roughly 20 percent higher than they are today in Germany. It will certainly be a challenge for the United States to approach Germany’s current level of emissions in only two decades. But it is hardly a fantasy, especially since Germany itself intends to lower its own emissions by a further 40 percent over this same period. If we accept Tynan and Victor’s view of what is realistic, then let us also accept that there is no chance of achieving the IPCC’s 2030 emission reduction target.

Finally, I fully share Simon Caney’s concerns about fairness and global leadership, issues my coauthors and I explore in depth in our UNIDO study. Let me offer here one concrete example that highlights what is at stake.

According to the World Bank, Indonesia’s per capita GDP was around $3,600 in 2010, which places it among the lower middle–income economies. Its per capita carbon emissions were roughly a tenth of those of the United States. But Indonesia aims to grow rapidly over the next twenty years, in the range of 6 to 7 percent annually. The Indonesian government projects a more than five-fold increase in emissions by 2030 if their GDP growth is fueled primarily by oil, coal, and natural gas.

The United States can hardly lecture Indonesia about emissions as a byproduct of growth. Still, if Indonesia and other emerging economies grow along a conventional fossil fuel trajectory, the chance of achieving the IPCC target would be close to zero. What if Indonesia were to adopt a clean energy investment program similar in spirit to the U.S. program I have sketched here? My coauthors and I estimate that a significant share of Indonesia’s energy needs for a rapid growth trajectory can be met by investing about 1.5 percent of annual GDP in clean energy. Emissions per capita would stabilize at the country’s current low level, and clean energy investments would generate about 750,000 more jobs initially than would spending the same money in the fossil fuel sector. The job gains would roughly double over the full twenty-year cycle.

The potential for U.S. global leadership in this setting is clear. The U.S. government can make major contributions by helping countries such as Indonesia finance and bring to scale their own transformative clean energy projects.