A debate has erupted in the climate science community about a Stanford University professor's high-profile 2015 study that claimed all of the US' energy requirements could be met with 100 per cent renewable by mid-century, largely using wind, water and solar with energy storage.  This debate has the potential to impact national policy and Canada's energy future.In June 2017, 21 energy experts, from institutions including Columbia University, Stanford and the Brookings Institution, published a rebuttal to Mark Jacobson's study in the Proceedings of the National Academy of Sciences, where Jacobson's paper originally appeared.In short, the scientists concluded that Jacobson's work “involves errors, inappropriate methods, and implausible assumptions.” Jacobson is standing behind his study saying there is “not a single error” in his paper.One of the 21 scientists who co-authored the rebuttal explained to the New York Times the reasoning for writing the rebuttal.“I had largely ignored the papers arguing that doing all with renewables was possible at negative costs because they struck me as obviously incorrect,” said David Victor of the University of California, San Diego. “But when policy makers started using this paper for scientific support, I thought, 'this paper is dangerous.'”The rebuttal also included this warning: “Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that rely almost exclusively on wind, solar, and hydroelectric power.”While coverage of this rebuttal has been limited to two major U.S. newspapers and the online energy and environmental media, Jacobson's original study had already spread across the globe, has been embraced by environmentalists, some policy makers and was even the focus of a feature segment on CBC's The National in March of 2016.There had been very little critical mainstream media coverage of Jacobson's paper. After all, he was and is promising a 100 per cent renewable Utopia and who wouldn't want that.The Canadian Nuclear Association has never advocated that one technology supply the entirety of the planet's (or even a single nation's) energy needs. Furthermore, history has shown that any Utopia is unattainable.We have always viewed nuclear as one of the important low-carbon sources of energy to combat climate change. Canada's nuclear reactor technology and uranium exports have, over the last 30 years, contributed globally to the avoidance of at least a billion tonnes of CO2 (in displacing fossil fuel sources) – a unique and ongoing contribution to global climate change mitigation which no other Canadian energy source can claim.Nuclear is one part of a low-carbon energy mix, even though supporters of other technologies often exclude nuclear in their energy mix futures.To speak of Canada's energy resources is to count our blessings. Oil, natural gas, hydro, nuclear, coal, wind, solar, biomass, wood.  The term “energy mix” cannot even begin to convey such a rich bounty of energy potential across the land.  Canada's energy endowment is a strategic advantage for the country and all its citizens.Given the credibility of those who authored the rebuttal report, there is no need to pile onto Jacobson in reiterating the flaws in his study.  However, it should be noted that the attention given by some policy makers and jurisdictions to the goal of 100 per cent renewable energy supply risks wasting time and resources while distracting us from more viable solutions.A more effective and realistic approach is foster collaboration that makes the best use of all available solutions to create a low-carbon future, allowing the world to meet emission targets while avoiding the potentially catastrophic impacts of climate change.Aside from some misguided advocacy for 100 per cent renewable energy supply, there is very little disagreement globally about what needs to be done to reduce GHG emissions.In April of 2014, the UN's Intergovernmental Panel on Climate Change recommended tripling the amount of energy use from renewable energy and nuclear power to keep climate change within two degrees Celsius. The International Energy Agency in their 2016 World Energy Outlook scenario, called for limiting an increase in global temperatures due to climate change to less than two degrees C.  This Outlook also predicted a requirement for global nuclear generation to increase by almost two and a half times by 2040. And last November, Canada's Mid-Century Long-Term Low-Greenhouse Gas Development Strategy report released at the COP22 Climate Change Summit included nuclear in all its models for achieving drastic GHG emission reductions by 2050.Canada and the world know what needs to be done. So let's focus on that mission instead of unrealistic and Utopian scenarios based on ideology instead of science.Dr. John Barrett is President and CEO of the Canadian Nuclear Association (CNA).  His professional career includes Foreign Affairs, National Defence and the Privy Council Office; international organizations such as NATO; and policy think-tanks such as the Canadian Centre for Arms Control & Disarmament.Before joining CNA, Dr. Barrett was Canada's Ambassador to the International Atomic Energy Agency, where he chaired the IAEA's Board of Governors, and was Canada's Ambassador and Permanent Representative to the Comprehensive Nuclear Test Ban Treaty Organization and to the United Nations in Vienna.  He has served as Ambassador to Austria and to the Slovak Republic.Dr. Barrett has a BA (Honours) and MA from the University of Toronto, and a Ph.D. from the London School of Economics.