For years, US public opinion polls on climate change and clean energy have displayed a remarkable consistency.

This consistency has been underappreciated because so much attention has focused on the most polarizing questions: Does climate change exist? Is it caused by humans? Public opinion on those subjects has fluctuated, mainly thanks to the hard turn back toward denialism on the right under the Obama administration.

But on other matters, there is wide, bipartisan agreement. Now, it seems, the Democratic establishment is taking note. Last week, nine Democratic pollsters — some of the biggest players in the party — circulated a memo making the case that there is a "National Consensus on Climate Change and Clean Energy."

Three things Americans agree on when it comes to climate change and energy

These are the three main elements of consensus, quoting directly from the memo:

A large majority of Americans consider climate change to be a serious problem and want action to be taken now to address it. There is broad support for the EPA’s Clean Power Plan to limit carbon pollution from electric power plants and require greater use of clean energy sources. There is avid support for increasing our use of clean, renewable energy sources, and voters expect the shift to these cleaner sources will lead to more jobs and lower electricity costs over the long term.

This third element has always been true. The second derives from a broader public support of pollution regulations, which has also remained persistently high over the years.

The first one, however, has been a long time coming. It now lends weight to the other two.

One other bit of the memo is worth quoting:

Voters continue to support the Clean Power Plan even after hearing arguments both for and against it, including criticisms related to its economic impacts. The most compelling reasons for voters to support the Clean Power Plan include: * The impact of unregulated carbon pollution on asthma and other respiratory illnesses, and the health benefits and cost savings that can occur by limiting carbon pollution now; * The moral irresponsibility and increased financial costs of passing the problem of climate change onto our children and grandchildren; and * The economic and environmental benefits of accelerating America’s transition to clean energy sources.

Advocates and politicians often seem to think they have to choose among these messages, but they all have an impact.

Polling breadth versus issue intensity

What's the lesson to take from this consensus? Is it that climate change and energy are winning issues for Democrats? Well, they can be.

As things stand now, the Republican stance on climate and clean energy policy — "No." — appeals only to the conservative base, not even to the majority of Republicans. But in this, as in so much else, the conservative base has a crucial advantage: It is passionate and organized.

Members of the conservative base hate concern over climate change; they view it as an excuse to expand government, and they hate government, much like they hate regulations. And they hate subsidies, at least subsidies to the Other — and right now, for the base, fossil fuels is Us and renewable energy is Them. Climate and clean energy are all tangled up with Obama and Democrats, and they hate Obama and Democrats.

Climate change mitigation and clean energy may have broad support among the rest of the electorate, but almost nowhere is that support as intense as the base's hatred. Support is — or has traditionally been — wide and shallow, while opposition has been narrow and deep.

What has changed in US climate politics

And that is precisely what has begun to change lately, precisely the significance of the growing climate movement and, yes, the Keystone campaign. There is now at least the seed of a constituency as passionate about climate and clean energy as the conservative base is in its opposition. And as any political scientist will tell you, passionate constituencies are more effective at scaring politicians than poll numbers.

The Democratic establishment is loath to acknowledge this, given the hostility toward left activists that pervades much of the center left. But there is a reason that broad public opinion on the urgency of climate change has begun shifting. It's because activists have finally begun to provide what social scientists call "social proof." Finally someone is acting like, not just saying, climate change is a crisis.

Beside that, clean energy is increasingly big business, with wind and solar companies beginning to throw around real influence at the state level. Through rooftop solar panels and mechanisms like community solar, more and more individuals have a direct stake in clean energy. Giant tech companies like Google and Facebook are seeking out green power. Even utilities are supporting reform, at least in some states. Clean energy is no longer the province of lefty idealists; there's serious money and institutional heft involved.

None of this has yet been enough to shake loose substantial Republican support — the bulk of national Republicans are from heavily red areas where primaries from the Tea Party right are the only real threat. But it was highly symbolic when, last month, Sen. Kelly Ayotte (R-NH) became the first Republican senator to support the Clean Power Plan. New Hampshire is a purple state, it contains lots of businesses in (or friendly to) clean energy, and Ayotte faces a real threat from her Democratic opponent in her upcoming race. From her perspective, if not yet the perspective of the rest of her party, support for the Clean Power Plan does not represent some wholesale shift to liberalism. It's just centrist common sense and an obvious political win. I doubt she'll be the last to reach that conclusion.

All these underlying tectonic shifts provide context for the numbers Democratic pollsters are highlighting. While support for clean energy has always been high, it is now backed by growing concern about climate change, an increasingly vocal activist movement, and support from large financial and commercial interests. Republicans are prevented from taking advantage of these shifts, tethered to their backward-looking base. That presents an enormous political opportunity for Democrats.

Further reading:

A few (okay, lots of) items on clean energy polling: