California's Hidden Methane: A New Climate Threat Uncovered
Methane is a powerful greenhouse gas, a major contributor to global warming. While often linked to industries like oil and gas or dairy farms, a lesser-known source is now drawing urgent attention: reservoirs. Environmental groups are pushing California air regulators to start tracking methane emissions from these waters, arguing it's a critical "blind spot" in the state's efforts to combat climate change. Experts agree that understanding these emissions is vital for making informed decisions about energy and solidifying California's role as a climate leader. Ignoring this source could undermine our collective efforts for a sustainable future.
Methane, the second-largest driver of climate change, isn't just escaping from industrial sites or farms; it's also rising from our reservoirs as underwater plants decay. Currently, California doesn't measure this contribution, despite its ambitious goals to cut methane emissions by 40% by 2030. This lack of data is seen as a significant gap in the state's climate strategy.
A coalition of environmental groups, including Friends of the River and Tell The Dam Truth, along with Patagonia, recently petitioned the California Air Resources Board (CARB) to mandate reporting on these emissions. They highlight that accurately tracking all sources of greenhouse gases is essential for effective climate action and for ensuring California remains a leader in environmental policy.
Studies show that "flooded lands," which include reservoirs, are a major methane source. The U.S. Environmental Protection Agency estimated 2022 emissions from these areas were equivalent to 44.4 million metric tons of carbon dioxide, comparable to the entire U.S. steel and iron industries, according to a 2024 report. Globally, research from 2021 suggests dams and reservoirs contribute 3% to 7% of all human-caused methane. Some hydropower plants, depending on their design and location, can even produce more planet-heating gases than coal-fired power plants per unit of electricity, as noted in a 2019 study.
While measuring reservoir methane can be challenging due to its dispersed nature, new aerial detection technology is on the horizon, with non-profits like Carbon Mapper working on better detection methods. Better data would help policymakers understand the true climate footprint of existing and planned projects, like the proposed Sites Reservoir. It could even inform operational changes for dams to reduce their emissions. Recognizing that hydropower, while a cleaner alternative to fossil fuels, isn't entirely carbon-free is crucial for minimizing environmental impacts and guiding sustainable energy development. The future of our planet depends on comprehensive understanding and action on all climate threats.