Democrats need a debate about where their party goes next. Obamacare's passage marked the rough completion of the social safety net that liberals began constructing during Franklin Delano Roosevelt's presidency. The end of the Iraq War drained Democrats of their foreign policy fervor. The rapid acceptance of gay marriage has robbed them of the next civil rights fight. There is work left to be done in all these arenas, but over time, the party will need to discover new dreams, much as Republicans have found the Ryan budget.

The closest thing Democrats have to an organizing concern is income inequality. But their solutions are neither sufficient to the scale of the problem nor quickening to the pulse. Raising the marginal tax rate on dividend income is not the clay from which political movements are crafted.

To many Democrats, the fight the party needs is clear: Hillary Clinton vs. Elizabeth Warren. But the differences between Warren and Clinton are less profound than they appear. Warren goes a bit further than Clinton does, both in rhetoric and policy, but her agenda is smaller and more traditional than she makes it sound: tightening financial regulation, redistributing a little more, tying up some loose ends in the social safety net. Given the near-certainty of a Republican House, there is little reason to believe there would be much difference between a Warren presidency and a Clinton one.

The most ambitious vision for the Democratic Party right now rests with a politician most have forgotten, and whom no one is mentioning for 2016: Al Gore.

Al Gore's vision of American politics

Gore offers a genuinely different view of what the Democratic Party — and, by extension, American politics — should be about.

Climate change is a real and growing threat to the world's future. In 2009, nearly every country in the world agreed that global warming must be held to less than 2 degrees Celsius. We're on pace to blow through that — warming the planet four degrees or more is horrifyingly plausible. No one really knows what that kind of temperature change — a swing that approaches the difference between most of human history and the Ice Age — would mean for humankind. The World Bank says there is "no certainty that adaptation to a 4°C world is possible."

Income inequality is a serious problem. But climate change is an existential threat.

Meanwhile, in Washington, the Chairman of the Senate Committee on Environment and Public Works is throwing snowballs on the floor of the Capitol because he believes cold weather outside his office proves global warming a hoax. This was his rebuttal, by the way, to news that 2014 was the hottest year on record. Something has gone very wrong in American politics.

When it comes to climate change, there's no one in the Democratic Party — or any other political party — with Gore's combination of credibility and commitment. Bill McKibben, founder of the climate action group 350.org, calls Gore's work on the issue "the most successful second act of any political life in U.S. history." Perhaps that's hyperbole, but it speaks to the regard in which Gore is held by climate activists. Though he's been out of office for 15 years, he's never left the climate fight. Gore has proven himself the opposite of those politicians who love the game more than they care about the issues.

Moreover, in an era in which very little moves through Congress, climate change is an issue where the president has real unilateral authority. The Environmental Protection Agency has the power to aggressively regulate greenhouse gas emissions — a process the Obama administration has begun, but that the next president will need to continue. Much of the crucial work on climate change requires coming to agreements with India and China — and that, too, is an arena where the president can act even if Congress is paralyzed.

Single-issue candidacies rarely go far in American politics, but then, Gore need not be a single-issue candidate. Indeed, the rest of his positions are closer in line with Democratic Party activists than, say, Clinton's. He opposed the Iraq War and endorsed single-payer health care, for instance. His Reinventing Government initiatives, mixed with his Silicon Valley contacts and experience, look pretty good for a post-Healthcare.gov era.

And there's a lot more on Gore's mind. His most recent book, ambitiously titled The Future, runs through the six forces he believes are changing the world: a globalized network of governments and corporations he calls "Earth, Inc."; worldwide communication technologies that are leading to the emergence of a "global mind"; massive shifts in power from West to East and from government to corporations; an economic system that too often devastates natural resources; revolutions in genomics, biotechnology, and other life sciences; and, perhaps most optimistically, the beginnings of a revolution in energy and agriculture.

The book has been blurbed by everyone from conservative economist Arthur Laffer ("transcends ideology while turning our attention to big issues, big ideas, and big solutions") to internet hero Tim Berners-Lee ("If you are concerned about the massive changes the world is just heading into, then you should read this book. If you aren't, then you must read it!").

You can believe Gore a visionary or you can believe him a blowhard, but he's offering a very different, and much more radical, vision of what politics should be about than even Elizabeth Warren, to say nothing of Hillary Clinton.

Gore can actually fund a campaign

Hillary Clinton is crushing her rivals in the invisible primary. The result will be a lopsided race once the campaign turns visible: her likely challengers don't have the name recognition, party support, campaign organization, or funding necessary to force a real contest.

Gore does. He begins with a powerful asset in presidential politics: credibility. As a long-serving senator and a two-term vice president, Gore has more direct political experience and at least as much claim to the triumphs of the 1990s as Clinton. He's also won more elections than Clinton — including the popular vote in a presidential campaign. There are few Americans who don't at least know his name. There is no one in the Democratic Party who won't at least take his call.

But Gore's experience and contacts now reach beyond politics — and into venues that would be enormously helpful to him if he wanted to fund an expensive race. He serves on the board of Apple, as a senior adviser to Google, and at the mega-venture capital firm Kleiner Perkins Caufield and Byers. He's also carved a path through finance and telecommunications, becoming fabulously wealthy — richer, even, than Mitt Romney — as an investor and mogul. And then there's his centrality in the environmental community, which is, itself, quite rich — it's easy to imagine, say, billionaire Tom Steyer gathering some friends and putting some massive Super PAC money behind Gore.

The problem with a Gore candidacy is Gore

The problem with a Gore candidacy, to be blunt, is Gore. He can be a wooden candidate. His relationship with the press is challenging, to say the least. He is an aging politician in a country that loves new faces. His finances are complicated, and he made an insane sum of money by selling his cable network to Al Jazeera. His divorce from Tipper Gore means his personal life isn't the storybook it once was. He is loathed by conservatives, who find his environmentalism to be rank hypocrisy from a jet-setting, Davos-attending mansion dweller — as politically polarized as concern over climate change already is, Gore could polarize it yet further.

But is that really so different from the list of drawbacks to a Clinton candidacy?

There's no sign that Gore has even a scintilla of interest in running for president (though he is making a May stop in Iowa...). And I don't think it particularly likely that even if he did run for president, he would win. Climate change is a threat, but I am far from convinced that doing anything about it makes for good politics.

But as bad as the odds are if a candidate does try to run for president with climate change at the center of his campaign, they're much worse if the major candidates from both parties largely ignore the issue. And Gore knows it. He's spent the last decade trying everything he can think of to force Americans to pay more attention to climate change. He's made movies, written books, given speeches, testified before Congress — he's even producing a Live Earth concert with Pharrell Williams.

All these venues are poor substitutes for the platform provided by a presidential campaign, and that goes double when one of the major two political parties is in intellectual flux. Gore cares enough about what comes next that he literally titled his last book The Future. But if he is really so obsessed with the future, then running in 2016 is his best chance to change it.