Six leading models agree: Rapid decarbonization of power, transportation sectors key to a successful energy transition

The latest United Nations IPCC Reports describe how limiting global warming to 1.5 degrees Celsius above pre-industrial levels can avert the worst impacts of climate change. That will require global emissions to drop by roughly half over the next decade and reach net-zero emissions near midcentury. With those goals in mind, the United States’ current Paris Agreement pledge is to reduce its greenhouse gas emissions by about 50 percent below 2005 levels by 2030. With less than eight years left to meet that target, what steps must be taken to get the job done?

A new study in the journal Science provides a clear and concise roadmap on how to achieve the 2030 U.S. climate goal that its coauthors say is technologically and economically feasible to implement, and delivers multiple long-term benefits. Moreover, its key findings are based on the consensus of six leading energy/economic models.

“Our study provides the first detailed roadmap for how the U.S. can reach its 50-percent greenhouse gas emissions-reduction target by 2030,” says lead author John Bistline, program manager in the Energy Systems and Climate Analysis Group at the Electric Power Research Institute. “This will require tripling the pace of historic carbon reductions, an ambitious but achievable target if stakeholders collaborate across all sectors. By comparing results across six independent models, we provide greater confidence about the policies and technology deployment needed to achieve near-term climate goals, laying the groundwork for an affordable, reliable and equitable net-zero future.”

Current U.S. energy-related climate policies are expected to lower carbon dioxide by only 6–28 percent from 2005 levels by 2030. To achieve the 50-percent goal for all greenhouse gas emissions, the roadmap presents several bold steps that require immediate and sustained effort.

First, about 70 to 90 percent of emissions reductions will need to come from the power and transportation sectors, and require participation from other economic sectors. That means reducing coal generation by 90 to 100 percent, deploying wind and solar at a capacity that is two to seven times more than the past decade, and expanding electric vehicle deployment so that EV shares as a fraction of new light-duty sales increase from about 4 percent (2021) to 34–100 percent (2030). The roadmap also calls for accelerated investment in emissions-reduction technologies for hard-to-abate sectors, and a more robust electric power grid that can handle a much higher share of renewables.

“Even just a few years ago, it was unthinkable to imagine such a rapid reduction in emissions,  but recent technological innovations in renewable energy technology and electric vehicles have substantially reduced the cost of decarbonization,” says study co-author Haewon McJeon, a senior research scientist at the Pacific Northwest National Laboratory. “Now the issue is less about how costly it would be to decarbonize, but how quickly enabling policies can be enacted to facilitate the transition toward a low-carbon economy.”   

Modeled policy options to enable this accelerated energy transition include clean energy tax credits, energy efficiency standards, and carbon pricing. Based on a range of results from the six models, the average cost of implementing the roadmap is $84 per ton of CO_2.

In the short term, roadmap-based policies could be designed so that low-income households could economically benefit from their implementation. In the long term, the overall policy cost would be offset by several nationwide benefits. The main monetary benefits are avoided climate damages, and avoided health costs due to major reductions in air pollutants such as sulfur dioxide, nitrogen oxides, and particulates. The roadmap could also create jobs, accelerate technological innovation and boost international competitiveness.

However, none of these benefits may be fully realized unless policies aligned with the roadmap are activated soon, maintains study co-author John Reilly, co-director emeritus of the MIT Joint Program on the Science and Policy of Global Change.

“Considering that the models from the six research groups are quite diverse, and that each group’s work was done completely independently, the level of agreement among the results is surprising,” says Reilly. “There are differences, of course, but all six models see most of the reductions coming from the power and transportation sectors, along with necessary contributions from all other economic sectors. The consensus is that achieving the U.S. emissions target by 2030 is technologically and economically feasible as long as we get on this transition path soon.”