The hypocrisy of the environmental left is well documented: Al Gore, Leonardo DiCaprio, and the other Hollywood eco-saints travel far and wide in their gas-guzzling limos and private jets to preach the importance of riding bicycles and to spread the gospel of wind and solar power.  However, perhaps more astounding than their "green life for thee, but not for me" lifestyle is the reality that environmental radicals, despite all their hollering to the contrary, don't actually want truly cheap and renewable energy.  In fact, the creation of affordable, clean, widely available energy is one of their greatest fears.

On March 9, a team from MIT and Commonwealth Fusion Systems announced in the academic journal Nature that they are closer than ever to making nuclear fusion a reality.  If successful, nuclear fusion would provide incredibly cheap, environmentally friendly energy to the world – and the researchers believe that the technology could be ready for a commercial rollout in as few as fifteen years.

As Fox News noted in a recent report on the potential discovery, "[n]uclear fusion is the be-all and end-all source of energy because, in theory, it's practically unlimited and has almost no downside.  It doesn't put carbon into the atmosphere like the burning of fossil fuels or generate radioactive waste like nuclear fission, which is the technology in current nuclear power plants."

If nuclear fusion is achieved, it will in relatively short order render much of the existing energy market useless.  Many traditional power plants would close.  Carbon dioxide emissions would be cut dramatically in countries with enough wealth to build nuclear fusion plants.  Billions of people would have access to affordable energy that they never had before.

This scenario might sound as though it's every environmentalist's paradise, but there's more to leftist environmentalism than obsessing about global warming.  For many on the left, growing human population sizes and their effect on the environmental is also a very serious concern.  For instance, in his population control book Ten Billion, environmentalist Stephen Emmott wrote, "Only an idiot would deny that there is a limit to how many people our Earth can support.  The question is, is it seven billion (our current population), 10 billion or 28 billion?  I think we've already gone past it.  Well past it."

University of Hawaii at Manoa professor Camilo Mora wrote in a 2014 paper in the journal Ecology and Society, "What caught my interest on this whole issue is how humans are causing the destruction of ecosystems.  At the end of the day ... we cannot stop hurting biodiversity if we don't stop reproducing so quickly."

Liberal environmentalists believe that more people means more problems, and history has repeatedly proven that when electric power and technological advancements become readily available, population growth inevitably follows.  During the twentieth century, Earth's population expanded by 400 percent, largely thanks to fossil fuel-powered societal improvements.

If nuclear fusion becomes a reality, billions of people who now live in extreme poverty (and thus don't consume many resources) would likely gain access to affordable energy, helping people living in communities plagued by disease and famine live longer, healthier lives.

From the leftist environmentalist's perspective, this effectively means that cheap energy is dangerous.  This is precisely why environmentalist Jeremy Rifkin said, "It's the worst thing that could happen to our planet" when the possibility of nuclear fusion was discussed in 1989.  Similarly, biologist Paul Ehrlich said it would be "like giving a machine gun to an idiot child."

If environmentalists are so concerned about population growth, why do they seem to unanimously support the use of wind and solar power?  The answer is because these forms of energy are more expensive than fossil fuels, which means it's unlikely they could soon catalyze population growth in the same way nuclear fusion could.  For example, the Institute for Energy Research found that solar power is three times more expensive than power generated from existing natural gas or nuclear plants.

If nuclear fusion becomes the world's most important power source in the twenty-first century, you can expect the climate change crisis to quickly evaporate.  In its place, the "Population Bomb" fear-mongering of the 1970s will once again rear its horrifying head.

Justin Haskins (Jhaskins@heartland.org) is executive editor and a research fellow at The Heartland Institute.