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In recent years, and media reports have blamed growing partisan hostility in the U.S. for shattered marriages, broken families, ruined holiday dinners and increased stress.

New suggests it may have an even broader impact, hindering democracies’ capacity to address climate change around the world.

“There has been a lot of research on the effects of political polarization at the interpersonal level, but ours is the first study to look at how it impacts the ability of democracies to mitigate climate change,” said senior author Don Grant, professor of sociology and fellow with the Renewable and Sustainable Energy Institute (RASEI). “We find that in democracies marked by deep interparty animosity, power plants—some of the world’s largest carbon polluters—emit CO₂ at significantly higher rates. And these outcomes are not unique to the U.S.”

More polarization equals more CO₂

In a study published in the , Grant and his colleagues looked at the annual CO₂ emission rates (CO₂ emissions per unit of electricity produced) from 20,115 fossil-fueled power plants across 92 democratic countries. They also looked at each country's level of what is known as "affective polarization," scored on a 0 to 4 scale. They found that in countries with greater affective polarization, or intense partisan hostility, democratic institutions are less able to effectively enforce climate regulation.

Don Grant

The study distinguishes ideological polarization—policy disagreements that can stimulate innovation—and affective polarization, a more personal and corrosive form of division in which citizens distrust and demonize those aligned with an opposing party. While robust debate about policy can strengthen democracy, affective polarization mobilizes citizens into rival stakeholder coalitions determined to obstruct policies advanced by their adversaries, said Grant.

“As these coalitions harden, governance becomes more difficult, existing policies lose effectiveness, and legislative processes designed to foster compromise are increasingly undermined,” he said.

Research shows affective polarization is on the rise globally, and climate change is a key wedge issue.

After controlling for other factors that could influence emissions, Grant’s study found that in countries with more affective polarization, plant-level CO₂ emission rates are significantly higher.

For example, in Uruguay, which had the lowest affective polarization score, emission rates were 11% below average. In Poland, which had the highest affective polarization score, emission rates were nearly 8% above average. The U.S. ranked near the top for affective polarization and above average for emission rates.

Changing times

In the early 1970s, political parties were, in many ways, less divided over issues like environmental protection. The U.S. Senate unanimously approved the Clean Air Act in 1970, authorizing the Environmental Protection Agency to establish national air quality standards.�� And utilities routinely included green-energy stakeholders as key collaborators in decision making.

Times have changed.

Grant argues that as people have grown more reluctant to associate with those with opposing views, utilities have disenfranchised many environmental groups, and power plants have become insulated from citizen and regulatory pressure. As a result, even in democracies with formal climate measures in place, the institutions meant to hold polluters accountable have failed to function as intended.

The study found that in countries with heightened interparty hostility, climate policies are less effective at curbing plants’ emissions. Also, government-owned power plants are particularly prone to emit more carbon.

“When polarization is higher, it may be harder to fully implement policies and for public utilities to reconcile the concerns of both pro-fossil fuel and pro-environment groups,” Grant said.

He speculates that if affective polarization continues, it may result in the repeal of long-standing climate mitigation policies.

“We already see evidence of this happening in the United States,” said Grant, referring to the EPA’s move to repeal the 2009 “endangerment finding,” which classified greenhouse gas emissions as a threat to public health. “Affective polarization is becoming a runaway phenomenon that threatens to erode democracies’ capacity to protect the planet.”