Mandatory state policies work best to curb power plant emissions, study finds

Nature Climate Change published the analysis, which shows that policies with mandatory compliance are associated with the largest reductions in power plant emissions.

"Based on the results of our study, we recommend that states adopt a policy of mandatory greenhouse gas emissions registry and reporting by power plants," says Eri Saikawa, an assistant professor in Emory's Department of Environmental Sciences. "We also found a significant impact in states that adopt public benefit funds aimed at energy efficiency and renewable energy programs."

Saikawa, an expert in public policy and the science of emissions linked to global warming, co-authored the study with Emory graduate Geoff Martin. Martin received his master's degree in environmental sciences in May and now works as an energy coordinator for the town of Hartford, Vermont.

Their findings were released as the U.N. Climate Change Conference (COP23) opens in Bonn, Germany. Delegates from around the world are gathering to hammer out details for meeting the goals of the 2015 Paris Agreement. The United States was among the 195 countries that committed to this framework to reduce greenhouse gas emissions -- although the Trump administration has said it plans to withdraw from this historic accord.

"Due to the current void in national leadership on the issue of climate change, efforts at the state and local level are more important than ever," Saikawa says. "U.S. cities and states need to step up and do what they can."

Global atmospheric CO2 levels increased at record speed last year, to reach a level not seen for more than three million years, the U.N. warned in a report released last week.

About 30 percent of U.S. greenhouse gas emissions come from the electric power sector. For the Nature Climate Change paper, the researchers started out to review the potential impact of President Obama's Clean Power Plan -- which established the first national carbon pollution standards for power plants. When President Trump took office, and announced plans to repeal the Clean Power Plan, the researchers shifted focus.

They analyzed 17 policies adopted by various states relating to climate and energy. States that adopted a mandatory policy for power plants to register and report greenhouse gas emissions showed the largest reductions, at an average of 2.6 million metric tons of carbon dioxide (CO2) emissions per year.

The second most significant policy involved public benefit funds allotted for energy efficiency and renewable energy programs. That policy was associated with a reduction of 1.5 million tons of CO2 emissions from power plants.

It's unclear whether one of these single policies was the actual driver of the reduction in emissions, or an indicator that a state takes climate change mitigation seriously and is attacking the issue on many fronts, Saikawa says.

For instance, three states -- New York, Connecticut and Oregon -- have each adopted both of the top two most effective policies, along with at least eight others.

Georgia, on the other hand, has adopted only one state policy to curb power plant emissions -- calling for voluntary reporting of emissions. Emissions are on the rise in Georgia, along with several other states that had adopted a voluntary reporting policy, the analysis showed.

In 2007, China surpassed the United States as the largest emitter of greenhouse gases globally. "But the per capita emissions in the United States are more than double that of China," Saikawa notes.

Emory is one of 50 universities from around the country to hold official U.N. observer status for COP23. Saikawa will be on the ground in Bonn to lead a delegation of 12 Emory undergraduates and one graduate student.

"It will be interesting to hear the take of officials from the Trump administration this year," Saikawa says.

The Obama administration played a key role in securing the Paris Agreement, to keep global warming to no more than 2 degrees Celsius since the start of the Industrial Revolution.

"U.S. coalitions from the state and city level are forming and they will likely have a strong presence at side events for COP23," Saikawa says. "Many groups are working at the local level around the world to try to meet the goal of the Paris Agreement."

Emory is co-hosting an event on Thursday, November 16 at COP23, focused on ways to mitigate climate change impacts in the developing world. Saikawa will appear on a panel, along with John Seydel, director of sustainability for the city of Atlanta.

"We'll be discussing how efforts at the city and state level in the United States might be replicated in other parts of the world," Saikawa says.