By Chloe Bennett
Dams have historically helped create drinking water, power and food. In an era of a warming planet, dams could create havoc.
In the Adirondacks, more than 500 dams listed by the state Department of Environmental Conservation have served a variety of purposes. Some are in the process of being restored, while others are unsound and could be removed by humans or nature.
As the Earth heats, weather experts expect severe storms to become more frequent, making dams more vulnerable to damage and flooding.
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Dams and climate change have a give-and-take relationship. Developing, restoring and removing dams can release carbon dioxide into the atmosphere. But the structures can also help store greenhouse gas and generate renewable energy.
Relationships include:
Dams can fail from overtopping caused by flooding, causing major destruction around them.
- So-called “thousand-year floods” could now happen each decade, experts warn.
- Floods can lead to erosion in the water bodies because the streams do not carry sediments the same way they would without large barriers.
- Instability in the rivers from erosion increases the threat of flooding to surrounding areas, Corrie Miller, aquatic organism passage restoration specialist for the Lake Champlain Basin Program, said. “And that’s something that really matters from a climate change adaptation perspective for the Lake Champlain Basin.”
Dams change the flow of rivers, impacting wildlife.
- Blocking fish and other animals from migrating to their established habitats can lead to population decline and a loss of biodiversity.
- Fewer fish can also lead to fewer meals for the animals who feed on aquatic life. Fragmented food chains can lead to a loss of biodiversity, already altered by climate change.
- “From a biodiversity perspective, in the context of climate change and the impacts that we’re expecting, removing dams that no longer serve any useful purpose but impede the connectivity of the river system is really important,” said Miller, who is also the former executive director of the Ausable River Association.
Dams are renewable energy sources that can reduce carbon production.
- Hydropower, energy generated by moving water, accounted for nearly 23% of the electricity used in New York in 2021, according to a recent state report, compared with wind and solar combining for less than 5%.
- Although dams are a key renewable energy source, a 2021 study from the Helmholtz Centre for Environmental Research in Germany found that dams can release carbon into the atmosphere from sediments in reservoirs.
- Still, the United Nations’ Intergovernmental Panel on Climate Change reports that hydropower has the potential to significantly reduce carbon production by replacing energy from fossil fuels.
Explore more: Dam series
See all the articles in our Adirondack dams series
Or are impoundments a big part of the climate change problem?
Pretty much all impoundments are flooded wetlands, or other areas that contained highly organic sediments. In contrast to natural lakes, impoundments usually have a much larger littoral zone, and usually have a lower waterbody volume to watershed area ratio – this all promotes eutrophication and methane gas release.
See:
https://www.science.org/content/article/hundreds-new-dams-could-mean-trouble-our-climate
and
https://pubmed.ncbi.nlm.nih.gov/30914638/
Finally, concrete’s sponge effect that traps CO2 only offsets up to a little more than 25% of the CO2 emitted to produce the concrete in the first place. And only that portion of the concrete exposed to the atmosphere can actually absorb gas from the atmosphere. Add to that the CO2 cost of delivery (22 pounds of CO2 for every gallon of diesel burned getting the cement to the job site – and a loaded cement truck gets perhaps 3 miles per gallon) and it’s hard to see just how the math ever works in favor of the CO2 reduction.