The liberal green groups are celebrating the "victory" of putting America's major coal producers out of business -- to say nothing of the tens of thousands of miners placed in unemployment lines. Several thousand more mining jobs were lost last month.

Now to get their next homicidal high, the leftists have turned their ambitions on the oil and natural gas industries.

Here is how Lena Moffitt, director of the Sierra Club's Dirty Fuels campaign, recently explained the grand, green vision:

"We are doing everything we can to bring the same expertise that we brought to taking down the coal industry and coal-fired power in this country to taking on gas in the same way ... to ensure that we're moving to a 100 percent clean energy future."

Wow! This is the agenda of lunatics. Scarier still is that the three most prominent democrats in America today aren't far behind in this maniacal mindset of killing off America's fossil fuels. President Obama says we have to shift to a "keep it in the ground" strategy when it comes to all fossil fuels. Bernie Sanders is the sponsor of a Senate bill that would effectively ban all oil and gas drilling on federal lands.

Hillary Clinton isn't far behind in the mania. Right off her promise to kill off all remaining coal jobs, she declared global warming "the defining challenge of our time" and hopes for a future when there is no drilling for oil and gas. This would end America's access to an estimated $50 trillion of energy resources.

What if, God forbid, these politicians and environmental groups actually prevail in shutting down American oil and gas development, as they have done with coal? What would it mean to the U.S. economy?

Let's start with jobs. There are still about 250,000 Americans directly or indirectly related to the coal industry. Under a Democratic administration in 2017, they would be gone for sure -- with miners reassigned to new positions under comrade Clinton's energy strategy.

But that's a pittance compared to employment and output in the oil and gas industry. Back in 2012, Pricewaterhouse Coopers completed a study (for the American Petroleum Institute) on the economic impact of American energy. PWC found that direct and indirect jobs related to oil and gas stood at just under 10 million.

These are truckers, construction workers, petroleum engineers, welders, pipefitters, geologists and many other hardhat workers. Many, if not most, are union members.

PWC also calculated that the value added to the U.S. economy from oil, gas and coal was about $1.2 trillion a year -- or about 8 percent of GDP. In other words, not producing fossil fuels means our economic growth would be instantly lowered by about 8 percent, which would make the last Great Recession seem like a picnic. Incidentally, the oil and gas industry also pays tens of billions of dollars in tax revenues every year -- so that flow would stop, too.

Of course, Clinton and Sanders say that we will replace all of this with windmills and solar panels. In other words, they want to shift back to the energy sources of the middle ages. Windmills will power our steel plants. Solar energy will electrify our factories and homes -- except when the sun doesn't shine. Germany thought they could "go green," and that strategy has raised energy prices and put the hurt to its manufacturing industries.

Even after more than $150 billion in government subsidies over the past decade, wind and solar power are so expensive and unworkable that they account for less than 6 percent of America's energy supply. And we're supposed to believe that we'll move from 6 percent to 100 percent green energy almost overnight.

Most amazing of all is that the people who believe this fairy tale are the same people who say that Donald Trump is crazy.