Methane is often found to be degassing from watery or icy reservoirs, and it is a major concern for climatologists. Although it rapidly decays in the atmosphere, the short sharp boost it gives to atmospheric warming means that it could set off a feedback cycle.
A quick rise in temperature will warm the world’s oceans and cryosphere, which – due to a quirk of chemistry – will allow more methane and carbon dioxide to escape. This will again warm the world, and so on and so forth.
Hydroelectric dam reservoirs tend to contain more methane than many natural sources, however, as they contain a plethora of concentrated organic matter that decomposes into various greenhouse gases. Upstream rivers also continually refill them with nitrogen and phosphorous that further exacerbate greenhouse gas production.
Although this finding is bad news, it’s important to know if the world is to proceed towards a low-carbon future. As many reports are already highlighting, the Paris agreement is a good start but not enough to prevent us from breaching that all-important (but somewhat symbolic) 2°C (3.6°F) warming limit. This finding highlights just how much more aggressive we need to be in terms of cutting carbon emissions.
Nevertheless, hydroelectric dams’ carbon footprint pales in comparison to fossil fuel-fired plants'. Ideally, a near-future energy revolution would ditch these harbingers of climate change and would instead focus on all renewables and nuclear power. They will still have a carbon footprint, of course, but it would be magnitudes lower than the one the world currently has today.
It’s unlikely hydroelectric dams will ever become the primary renewable energy source anyway. After all, you need a network of mountains and rivers for these to work – not something that every nation on Earth possesses.
The famous Hoover Dam. Andrew Zarivny/Shutterstock