1. Particularly in tropical regions, hydropower reservoirs emit significant amounts of greenhouse gases.
According to a peer-reviewed study, methane from reservoirs accounts for more than 4% of all human-caused climate change comparable to the climate impact of the aviation sector. In some cases, hydropower projects are producing higher emissions than coal-fired power generating the same amount of electricity plants
2. Rivers take about 200 million tons of carbon out of the atmosphere every year.
Additionally, the silt that rivers like the Amazon, Congo, Ganges, and Mekong carry to the sea feeds plankton and absorbs large amounts of carbon. Hydropower projects and other dams impair the role of rivers to act as global carbon sinks by disrupting the transport of silt and nutrients.
3. Hydropower dams make water and energy systems more vulnerable to climate change.
Unprecedented floods are threatening the safety of dams: In the US alone, floods have caused more than 100 dams to fail since 2010. Dam building has also exacerbated flood disasters in fragile mountain areas such as Uttarakhand in India. At the same time, the increasing frequency of extreme droughts makes hydropower economically risky and has greatly affected countries from Africa to Brazil that depend on hydropower dams for most of their electricity.
4. In contrast to most wind, solar, and micro-hydropower projects, dams cause severe and often irreversible damage to critical ecosystems.
Due to dam building and other factors, freshwater ecosystems have on average lost 76% of their populations since 1970.
5. Large hydropower projects have serious impacts on local communities and often violate the rights of indigenous peoples to their lands, territories, resources, governance, cultural integrity and free, prior informed consent.
Dams have displaced at least 40-80 million people and have negatively affected an estimated 472 million people living downstream. The resistance of dam-affected communities has often been met with egregious human rights violations.
6. Large hydropower projects are not always an effective tool to expand energy access for poor people.
In contrast to wind, solar and microhydropower, large hydropower dams depend on central electric grids, which are not a cost-effective tool to reach rural populations. Particularly in Sub-Saharan Africa and the Himalayas, large hydropower projects are often built to meet the demands of mining and industrial projects, despite developers’ claims that the energy is intended for the poor.
7. Large hydropower projects are a costly and a time-consuming way to produce energy.
8. Unlike wind and solar power, hydropower is no longer an innovative technology, and has not seen major technical breakthroughs in several decades.
Unlike with solar power, climate funding for large hydropower projects will not bring about further economies of scale, and does not encourage a transfer of new technologies to countries in the Global South.
9. Wind and solar power have become readily available and financially competitive and have overtaken large hydropower in the addition of new capacity.
As grids become smarter and the cost of battery storage drops, new hydropower projects are no longer needed to balance intermittent sources of renewable energy.
10. Hydropower projects currently make up 26% of all projects registered with the CDM (Clean Development Mechanism), and absorb significant support from other climate initiatives.
Finance for large hydropower projects crowds out support for real solutions such as wind, solar and micro hydropower, and creates the illusion of real climate action.