What is the “3.5% rule” beloved of climate protesters?

    27 Nov 2021

    Mobilizing a certain proportion of the population will not guarantee a movement’s success, believe The Economist journalists. Let’s get through their opinion.

    Last weekend, 100,000 activists marched through Glasgow, where the UN’s climate summit was taking place, demanding that governments do more to tackle global warming. Many carried the banners of the Extinction Rebellion (XR), a global environmental movement specializing in disruptive protests. According to XR’s website, it needs “the involvement of 3.5% of the population” if it is to succeed in achieving its aims. They are still some way off: in Britain, that would amount to around 2m people. The “3.5% rule” comes from Erica Chenoweth, a political scientist at Harvard, who found it was a useful predictor of a protest’s success. What is so special about this figure?

    The 3.5% rule posits that no government can stand up to that share of the population mobilizing against it. Ms. Chenoweth came up with it in 2013, after studying 323 violent and non-violent protests that occurred between 1900 and 2006 worldwide. In every case when at least 3.5% of the population attended a “peak” event, such as a mass gathering, they achieved their aims. One example was Georgia’s Rose Revolution of 2003. More than 180,000 protesters (equivalent to 4.7% of the country’s population) gathered outside the parliament to oust President Eduard Shevardnadze, a strongman left over from the Soviet era. Protesters handed out roses to soldiers, who lowered their weapons. Shevardnadze was removed from power without bloodshed.

    It is not always that simple. In 2019, some 2m Hong Kongers – more than a third of the city’s population – took part in a demonstration against plans to bolster extraditions to mainland China. In the years since, the clampdown by Hong Kong’s authorities has only intensified. There are caveats too. Non-violence tends to work better than violence. Ms. Chenoweth’s research showed that serious political change occurred 53% of the time after peaceful protest compared with 26% after violent protest. Peaceful demonstrations present fewer physical barriers to participation: children, disabled people and the elderly can join a march, whereas riots are generally started by physically fit young men. Non-violence is also more likely to win sympathy from security forces.

    That augurs well for climate protesters, who are often disruptive but rarely violent. But the 3.5% rule may not be compatible with their demands. Ms Chenoweth’s research accounts only for “maximalist” movements with clear goals such as regime change or territorial independence. The demands of climate activists, by contrast, are often vague. XR’s website lists the group’s three main demands of world governments: “Tell the truth”, “Act now” and “Go beyond politics”. And global warming tends to attract protesters, well, globally. In 2019, 4m people marched in protest at rising temperatures, many of them teenagers inspired by Greta Thunberg’s school strikes. In one place that number would be difficult for any government to ignore. But spread across the world the impact was weakened.

    That does not make climate protests useless if they fail the 3.5% test. After the climate demonstrations in 2019, internet searches for “climate change” surged worldwide. Public awareness makes politicians pay attention. And smaller, more extreme protests may act as a “radical flank” that increases the political leverage of moderates, who are seen as a more palatable alternative by lawmakers. XR and other environmental movements may see the 3.5% rule as an important predictor of success, but it isn’t the only one.


    There are some movements beyond Extinction Rebellion. Read more about the protest groups fighting on the climate frontline here.

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