Social behavior could alter the course of climate change

Pushing harder for climate action in one part of the world can quietly weaken it somewhere else, according to a new study.

Using a model that splits the globe into five regions, researchers showed that social norms can speed up carbon cuts in some places and stall them in others.

The finding suggests that culture and peer pressure deserve a place alongside economics in forecasts of how the world will handle warming.

The study also carries an awkward lesson for climate campaigners, because a message that rallies one country can backfire in the next.

Models leave out data

Most large climate models tend to treat people as purely rational economic actors.

They assume individuals weigh the price of going green against the cost of a hotter planet, then act in their own financial interest, leaving out the messier reasons humans actually do things.

A new model built at the University of Waterloo sets out to loosen that assumption. The research was led by Dr. Amrita Punnavajhala and Professor Chris Bauch.

Weighing support for climate mitigation

In the model, every person decides whether to support climate mitigation in an effort to reduce emissions. They do so by weighing three pressures at once.

One of those pressures is money. Alongside the cost of switching to clean power are the damages that people expect from a hotter climate and the pull to agree with whatever their neighbors already think.

“Our model recognizes that people are also influenced by social norms, whether that’s eating more beef or choosing reusable water bottles, and those behaviors can significantly affect climate change mitigation,” said Bauch.

The same team built a simpler version of this idea years ago, treating the whole world as a single population that talks itself into action.

The new work breaks that population apart, since attitudes toward warming are nowhere near uniform across the planet.

Five regions pull apart

Wealthy industrialized countries in the OECD, along with the reforming economies of Eastern Europe and the former Soviet Union, begin with weaker public support for cutting emissions.

They possess a fainter sense of concern that climate change threatens their everyday lives.

The poorer, more exposed regions, such as Asia, Latin America, and the Middle East and Africa, start further ahead. Their people back action more strongly and feel the danger more keenly.

Africa and the Middle East are considered the most vulnerable, while the wealthy nations are more secure. Those starting points come partly from a global survey of 125 countries.

It found that people in more vulnerable places are more willing to pay to slow warming, and that close to 70% of people worldwide would give up one percent of their income to do it.

Adoption of climate mitigation

When the model incorporated these differences, the model splits the world in two.

Under a middle-of-the-road future, the poorer regions reach majority support for cutting emissions by around 2030.

At the same time, the OECD and the former Soviet bloc do not cross that line until roughly 2060.

The rich regions drag their feet even though they stand to save the most from cheaper renewable energy.

In the bleakest scenario, support for action dies out everywhere except Asia, locked in place by norms that reward going along with the crowd.

Discussion can backfire

More talk about climate change usually builds support for doing something. But the model found that in the wrong conditions, the same conversation can harden people against action.

“We found that greater discussion about climate change often increases support for mitigation, but in some regions, it can also fuel anti-mitigation sentiment,” said Punnavajhala.

The effect depends on which opinion already holds the majority, since louder conversation spreads that view faster, whichever way it leans.

The limits of persuasion

The speed of that spread, which the researchers call social learning, turns out to have a sweet spot.

Push it too fast in countries that lean against action, and opposition spreads before the case for change catches up.

The effect on the thermometer is stark. Moderate learning holds the model’s peak warming near 5.0°F (2.8°C) above pre-industrial levels.

Increasing social learning too much in wealthy countries drives the peak to about 6.3°F (3.5°C), and sluggish change everywhere lets warming climb to roughly 6.8°F (3.8°C).

Because every region shares the same atmosphere, one region’s effort changes the incentives for all the others.

When a big emitter cuts back, global warming eases a little, and that relief can sap the urgency felt elsewhere.

“If Asia increases its mitigation efforts, global warming slows slightly, which can reduce the perceived urgency in OECD countries such as Canada and the United States,” said Bauch.

He warns that the loosened pressure can create harmful consequences that build over decades.

The free rider problem

The model makes the trade concrete. Stronger action by Asia, raising its cumulative effort by about 80%, let Latin America ease its own effort by roughly 40% while warming stayed in check.

Economists call this free riding, in which one group coasts on the work of another. Left alone, the feedback pulls the world’s regions apart rather than together.

The places already suffering most move fastest to cut emissions, which cools the planet just enough that the comfortable regions can grow more complacent still.

Smarter climate policy

What the model adds is a warning that culture can swing the outcome as hard as cost.

Depending solely on how these social forces play out, the peak temperature under a high-emissions path varies by several degrees.

That argues against one-size-fits-all messaging and in favor of campaigns tuned to each region’s mood and means.

It also strengthens the case for binding international agreements. An earlier study suggests those work best once regional momentum is already building.

When the researchers let regions encourage one another directly, that closer connection trimmed worst-case peak warming by more than 9°F (5°C).

This took place as committed regions stiffened the resolve of waverers next door.

The social side of climate action

The authors call the model exploratory rather than a prediction, since it still simplifies how governments and the media move opinion.

Even so, it argues that the human half of the climate problem deserves the same rigor as the physical half.

“There are constant feedback loops between climate change and human behavior. Understanding those relationships will be essential to reducing emissions and building a more sustainable future,” said Madhur Anand at the University of Guelph.

The study is published in the journal Nature Communications.

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