Hydropower dams are not the solution to the climate crisis

On August 9, the United Nations Intergovernmental Panel on Climate Change (IPCC) reiterated what many of us already know: climate change is accelerating and aggressive action must be taken to contain the tide of this impending global catastrophe. The report found that severe climate impacts in the form of droughts, forest fires, floods and super storms are already upon us and will intensify if we do not act immediately. The report, produced by 234 scholars who draw on over 14,000 peer-reviewed studies, is a “Code Red for Humanity”.

The report explicitly names methane as the main culprit behind the crisis and suggests “strong, rapid and sustainable reductions” in emissions to prevent further damage. Methane emissions from human activity account for about 25 percent of total global warming. Our best opportunity to reverse the dire trajectory of the climate crisis before more tipping points are triggered, so we cannot rely on building more hydroelectric dams.

Although claimed by some to be a clean source of energy, hydroelectric dams generate huge amounts of methane. In fact, nearly 80 percent of greenhouse gas emissions from reservoirs created by dams are methane, which over a decade or two is more than 86 times more potent than carbon dioxide in accelerating climate change effects before it’s too late.

Dams and reservoirs create constant methane releases, often driven by microbes that feed on flooded vegetation. Scientific research shows that a hydropower plant can cause more warming than a coal-fired power plant in the first few years. And when reservoirs experience fluctuations in water levels – for example during a mega-drought – this increases the amount of methane released that was previously retained in the deeper parts of the water in the atmosphere. In addition, the construction of new dams, which use large amounts of cement and concrete, is itself a significant source of methane emissions.

But methane isn’t the only problem with hydropower. The problem is the dams themselves. The structures are ruining ecological habitats by literally standing in the way of fish migration. The reservoirs created by dams raise water temperatures, which in turn reduces oxygen levels and destroys fish populations. Dams also trap silt and other nutrients that would otherwise naturally feed downstream habitats.

Reservoirs and dams can quickly increase freshwater evaporation, which would be a problem in any climate, but is particularly problematic given the historic mega-drought that continues unabated in the American West.

In addition, dams do not affect all communities equally. Rather, the burden is often placed on Native American tribes and other frontline communities. Be it rerouted waterways and negatively impacted fisheries, an increase in methylmercury or culturally significant areas that have been flooded into a reservoir, hydropower is indeed a question of environmental justice.

The unsuitable structural conditions of dams are not even taken into account. About 2,000 dams in the US are in need of repair. Over two-thirds of all dams in the United States have expired or are nearing their expiration date. It is time we stopped throwing good money on bad money.

Marc Yaggi is the managing director of the Waterkeeper Alliance.