This April 28, 2015 photo shows Pope Francis and United Nations Secretary General, Ban Ki-moon (R) holding a private meeting at the Vatican. (AFP PHOTO / OSSERVATORE ROMANO.)

This is the first installment of a weekly column on energy and the environment — “Planetary.” This column will try to draw together major trends in this sphere and provide analysis and perspective that extend beyond our daily reporting. We welcome ideas from readers about major topics I should write about — click on my byline to email me, or tweet @chriscmooney.

Back in 2009, there was an exceedingly weird idea afoot — that President Obama would sweep into office, get a climate change bill through Congress, sign it and then go to the mega-international climate meeting in Copenhagen and take carbon cuts global. With the U.S. leading the way, the world would then fall in line and global emission cuts would follow.

This was what you call extreme over-optimism. Instead, Obama spent his political capital on a health care bill, climate legislation died in the Senate, a pseudo-scandal dubbed “ClimateGate” erupted, and in snowy Copenhagen – the weather itself was a symbolic backdrop — the resulting accord was widely panned.

That’s why I’m so hesitant to suggest that 2015 may be another 2009 (only with more…follow-through).

And yet. The pieces, again, look to be coming together. And when I say pieces, what I mean is an amalgamation of political and also psychological or public opinion related developments that, combined, just might have the potency that similar elements, in 2009, did not.

What are those elements? Well, first, there’s Pope Francis. By all accounts, in coming weeks the equivalent of a moral earthquake will occur, as the pontiff unleashes a historic papal encyclical on the environment. It is expected to call on global Catholics to become environmental stewards and, in particular, to care about climate change because of how it imperils the poor and disadvantaged around the world.

[Why Pope Francis is about to make a dramatic wave in the climate debate]

I don’t think you should underestimate how big a deal this is. It has already ruffled Catholic Republican presidential candidate Rick Santorum enough that he actually called on the Pope to stay out of scientific matters.

From a public opinion standpoint, U.S. Catholics in particular seem to be right in the middle on the climate issue. They’re not highly skeptical, as are members of some conservative Protestant groups, but they’re not exactly bullish, either. In sum, they’re a gigantic bloc that really could move. And moreover, the sheer visibility of the Pope taking this stand as a matter of doctrine — and also potentially bringing it up before the U.S. Congress in September — will present a major media spectacle.

Everyone will know about it and talk about it.

In some ways as important, though, is another factor: The heat. The Earth has begun 2015 with its hottest four month start to a year on record, according to the National Oceanic and Atmospheric Administration. The planet has seen a temperature that was “the highest for January–April in the 1880-2015 record,” the agency says.

That could certainly taper off. But the planet is also officially in an El Niño mode – with a currently forecast 80 percent chance of staying there all year. El Niño years tend to be hotter — unleashing heat from the Pacific Ocean. “This El Niño event, as it continues to take hold, will definitely increase 2015’s chances to place among the warmest years, if not the warmest, on record,” wrote NOAA researcher Deke Arndt recently.

If that really happens, it would be a fitting conclusion to a year in which NOAA scientists also officially stood up and debunked the idea of a global warming “pause.”

But steady now. There was talk of El Niño last year, too. It didn’t materialize. And this column is no climate forecast. All I’m saying is that if temperatures do continue their current run — buoyed by an El Niño — then people will begin to really notice — physically, but also mentally, as talk of another hot year increases and increases.

And then finally, there’s policy. When world leaders meet in Paris at the end of this year, they will know that this time around, a binding global agreement on emissions must come, or else they risk further disheartening those who already have much cause to question the international climate negotiation process.

But this time, negotiators come to the table not only with more pressure on them than ever to reach a compromise, but also with the United States, China, and the European Union having set forth commitments to cut emissions already. Those are the world’s three biggest emitters right there. In particular, the U.S. China agreement of late 2014 took off the table the two biggest finger-pointing reasons to shirk climate action: That the world’s historically biggest emitter (the U.S.) or its current biggest emitter (China) hadn’t done anything.

As for the U.S., its president has lately acted as though there was no issue that mattered more to him than climate change, seeming to seize every possible opportunity to highlight it. It wouldn’t be surprising at all to see Obama in Paris, lending as much heft as he can to the negotiations.

So there’s all of this — and yet clearly, those thinking climate action would come easily or quickly have been wrong before. They’ve been wrong because they didn’t foresee just how strong the resistance was, and just how difficult international climate negotiations really are.

But I think we can say, safely, this much at least. Climate policy has momentum, momentum of a kind that we’ve rarely seen before. And momentum matters.