That chart comes from a report issued by the U.S. Energy Information Administration (EIA) on Wednesday morning. And it looks like this:

The headline here is certainly worth celebrating: Renewable sources of energy are now the second-largest source of electricity in America, generating 21% of the total. It’s not actually the first time this has happened; back in 1950 when the agency first began, hydro power was the nation’s No. 2 source of electricity. But there are only so many places that can be, or should be, dammed to produce electricity and unfortunately, coal is abundant. The next 60 years were the Age of Coal, with that most destructive of fossil fuels growing ever more dominant.

But what’s happened since 2005 is genuinely amazing. King Coal was toppled from his throne in a revolution that was one part natural gas fracking and one part increasingly cheap wind and solar. And this is the first time that the EIA has placed production from renewables above that of coal.

The reason natural gas grew so rapidly over the last two decades is easy to describe. Gas is easily used in the same kind of steam-cycle power production as coal, but it has several advantages. First, gas need not be stored in huge stockpiles on the ground—stockpiles that are subject to both weathering and to spontaneously catching fire. Second, burning gas produces a lot of CO₂, but in terms of other byproducts, it’s almost infinitely cleaner than coal so there’s no need for expensive “scrubbers” that eliminate things such as the sulfur dioxide from coal that causes acid rain. Third, gas doesn’t leave behind tons of ash that has to be stored in great eroding mounds or slurry pools that constantly threaten to flood the area in toxic sludge.

But more important than any of that, gas plants can be small. Utilities can create gas generators of almost every size, and simply add more when needed. Coal plants range from merely huge to absolutely titanic, and the economies of coal make it difficult to scale them up or down.

So why didn’t companies use gas to begin with? Because before the mid-1990s, the price of natural gas varied widely. That made gas suitable for building small “peaking” plants that could handle extra demand on those days when the grid was at maximum demand, but left cheaper coal to carry the main demand. It was only after fracking became widespread and the price of gas stabilized at a rate that made it competitive with coal that the big switchover began.

What’s striking about the renewables line on the chart is how fast it doesn’t grow until about 2005. That line reflects mostly more hydro power, small-scale solar, and an irregular trickle of wind projects over the span of decades. It’s not until prices for both wind and solar became cost-competitive with coal that things started to change quickly. The decades in which annual changes in renewables could be measured in a fraction of a percentage point charge abruptly into a steady rise, and the rate of that rise is increasing.

By 2018, the cost of building new solar or wind power from scratch had reached a point where it was less than the cost of simply maintaining an existing coal plant, even ignoring the cost of coal. That’s a powerful incentive to switch. Even as Donald Trump was talking about how he was going to “save” the coal industry, it was plummeting in a near freefall, shedding both capacity and workers.

Overall, what the chart shows is just this: Things can change. With the right motivations, they can change quickly. The one problem with this chart is that it might tempt everyone to just sit back and let the market handle it. After all, the last two decades show that gigawatts of production can change almost overnight when dollars are on the line.

Only there are reasons that the government still has to shove, and shove hard, to make things move rapidly enough and in the right direction.

• Gas is cheap. Thanks to fracking, there is an absolute glut of natural gas—so much that at several points, all the storage facilities in the nation have been nearly choked with the stuff. How long will fracking allow fields from Texas to North Dakota to Pennsylvania to continue producing at a record pace? No one knows. But right now the use of natural gas is still increasing. That means more CO₂ and more spilled methane.
• Innovation needs to come home. When Republicans fume about Chinese solar panels, they’re at least half right. Part of the price reduction for solar has come through availability of cheap panels manufactured mostly in China or India. The U.S. continues to make breakthroughs in solar cell efficiency, but needs help in turning those improvements into an industry that sees American panels being shipped around the world.
• Inequity is a market inevitability. Left to itself, the market will gradually close out coal plants and create more renewables. But it will also leave behind ecological disasters. Coal is a dying extraction industry. What such industries leave behind are unreclaimed lands, crumbling plants, and communities in ruin. Government intervention is absolutely necessary if this failing industry is going to be ushered out the door in a way that gives workers and the surrounding areas a soft landing rather than seeing coal executives wave bye-bye beneath golden parachutes. And the government needs to pay particular attention to both cleaning up and providing jobs to communities of color, which are often right in the zones of heaviest pollution.
• It’s not fast enough. The chart shows the energy industry can change more quickly than anyone believed. Now it has to change faster. We don’t have more decades to make this transition, not when every wasted year represents more of that drought, fire, and flood we mentioned back at the beginning.

The abrupt change in America’s energy mix should be good news to everyone. Even if much of that production has switched to natural gas, it shows that enormous change is possible.

Now let’s make it happen again. Faster.