Nuclear Energy: A Climate Hero

Around the world, nuclear power has led to the accidental decarbonization — the best kind, as the byproduct of sensible energy and economic policy.

In the fight against climate change, nuclear energy is one of our most powerful technologies. It generates electricity with essentially zero carbon dioxide emissions at the point of production, and even when considering the full life-cycle (mining, construction, fuel processing), its carbon footprint is extremely low. According to comprehensive assessments by the Intergovernmental Panel on Climate Change (IPCC), nuclear power’s life-cycle greenhouse gas emissions are on the order of 12 grams of CO₂ per kilowatt-hour. This is comparable to wind turbines (around 11 g/kWh) and much lower than solar panels (~40–50 g/kWh) – and orders of magnitude below coal (820 g/kWh) or natural gas (490 g/kWh). In practical terms, a coal-fired plant emits over 100 times more CO₂ per unit of electricity than a nuclear plant. By avoiding carbon emissions, each nuclear reactor helps avert the climate-altering buildup of greenhouse gases that is warming our planet. In 2021, nuclear energy globally prevented an estimated 471 million metric tons of CO₂ from being emitted (compared to if that power came from fossil fuels) – equivalent to taking 100 million cars off the road. Every nuclear plant, by running without a smokestack, is a powerful climate mitigation tool.

A key advantage of nuclear power in addressing climate change is that it provides steady, around-the-clock generation. Nuclear reactors operate at very high capacity factors – often above 90% on average – meaning they run near full power most of the time. In the United States, for example, nuclear plants produce maximum power more than 92% of the hours in a year, which is nearly twice as much as coal or gas plants and 3–4 times more than wind and solar farms. This reliable output is crucial for decarbonizing the grid because it does not require constant fossil-fuel backup. Solar and wind energy are essential parts of a sustainable future, but their intermittent nature (dependent on sunlight and wind) can necessitate balancing with gas turbines or massive energy storage. Nuclear energy, by contrast, can function as a firm baseload power source that runs through the night, winter, and calm days, avoiding the cost and complexity of dual systems.

A grid with substantial nuclear capacity doesn’t need to build as many standby power plants or large battery banks to maintain supply when the weather doesn’t cooperate. This simplifies the transition to a low-carbon energy mix and often reduces overall system costs. Countries that invest in nuclear can thereby streamline their decarbonization: a single reactor can generate as much yearly electricity as about 3–4 wind farms or 6 million solar panels would, due to nuclear’s high utilization rate. By stabilizing the grid, nuclear power makes it easier to integrate other renewables too, forming a synergistic relationship in climate strategy.

Chart comparing hourly carbon intensity of the French and German grids. France is a nuclear powerhouse, while Germany recently shut down its nuclear fleet. Chart by Grant Chalmers.

Real-world examples underscore nuclear’s proven ability to decarbonize electricity on a large scale. France is a standout case – it generates roughly two-thirds of its electricity from nuclear reactors and has for decades maintained one of the lowest-carbon grids in the world. Per unit of electricity, France emits only about 85 grams of CO₂ per kWh, compared to a world average of 438 g. This six-fold difference is largely thanks to nuclear displacing coal and gas. France’s bold nuclear build-out in the 1970s–1980s slashed its power sector emissions and today, French citizens enjoy electric power that is both cheap and nearly carbon-free, all while exporting surplus clean electricity to neighboring countries. South Korea is another success story – by adopting nuclear (which now provides about 30% of its electricity) alongside some gas and renewables, South Korea rapidly industrialized with relatively low emissions. And in Ontario, Canada, nuclear energy enabled the province to completely phase out coal power by 2014. By refurbishing and expanding nuclear plants, Ontario filled the gap left by shuttered coal stations. The result was a significant cut in greenhouse gases and cleaner air; the province went from having dozens of smog advisory days each year to nearly zero. This coal-to-nuclear transition has been hailed as a model for climate action – it was equivalent to removing millions of cars’ worth of CO₂ emissions, while simultaneously delivering public health benefits as noted earlier. These case studies show that nuclear energy can rapidly and affordably decarbonize grids, at scale, in real time – not just in theory.

Chart showing the fastest 5-year deployments of clean energy throughout history. Although renewables can be constructed quickly, the largest and fastest additions of clean energy have been dominated by nuclear and hydropower. Chart by Grant Chalmers.

Mitigating climate change is not only an environmental imperative but also a medical and public health necessity. The WHO has declared climate change “the single biggest health threat of the 21st century”. As global temperatures rise, we are seeing more frequent and intense heat waves (which can be deadly for the elderly and vulnerable), the spread of infectious diseases like malaria and dengue fever into new regions, increased asthma and allergies from longer pollen seasons, and food and water insecurity from droughts and extreme weather. Climate change is already causing suffering, and it will get worse without swift action. By one estimate, between 2030 and 2050 climate change could cause an additional 250,000 deaths per year globally from malnutrition, malaria, diarrhea, and heat stress. Cutting carbon emissions can literally save lives by avoiding these dangerous health impacts. Nuclear energy, as a dispatchable clean power source, allows us to reduce greenhouse gases without sacrificing reliability or resorting to polluting backup generators. In a very real sense, every reactor built is a boon to public health in the long term – it helps stabilize the climate and thereby prevents climate-related illness and injury.

Medical professionals are increasingly vocal about the climate crisis, noting that preventing unchecked climate change will avert heatstroke deaths, trauma from disasters, and the collapse of healthcare systems under climate-extreme events. By deploying nuclear alongside renewables, we can achieve deep decarbonization faster, protecting ecosystems and the conditions for human health. Decarbonizing the energy sector is like a vaccine against a host of climate-linked health problems; and nuclear power is a vital component of that inoculation.