Joe Biden is leading the Democratic primary by a wide margin — nearly 27 points, according to the latest polling average. So what would he do on the most important problem facing America and humanity writ large? On climate change, Reuters reports that Biden wants a "middle ground approach" to appeal to both liberals and blue-collar Trump voters, whose "backbone … will likely include the United States re-joining the Paris Climate Agreement and preserving U.S. regulations on emissions and vehicle fuel efficiency," plus support for nuclear, natural gas, and carbon capture.

It hardly needs to be said that this "approach" is pathetically inadequate for dealing with climate change. And if Biden is elected, the timidity and learned helplessness of the Democratic rank-and-file might just have wrecked the global climate.

The problem with Biden's climate agenda, obviously, is that it isn't aggressive enough. Top climate scientists agree that the world has to cut its greenhouse gas emissions in half by 2030 — that would be two years from the end of a Biden presidency, if he wins two terms — to stay under 1.5 degrees of warming, and fully to zero by 2050. How to allocate those cuts is a tricky question, but given that the United States is responsible for a plurality of past emissions, and would find green upgrades considerably easier than most countries due to our wealth and inefficiency, it only makes sense for the U.S. to cut even faster than that.

Essentially, what we must do to preserve a global climate is hack down our emissions as fast as we possibly can, and conduct a crash research program into zero-carbon agriculture, transportation, and industry as part of a coordinated similar effort with other countries, above all China and India. We may or may not be able to hit those targets, but every tenth of a degree of warming headed off means lower seas, less catastrophic weather, fewer crop failures, fewer climate refugees, and so on.

And while there's nothing wrong with efficiency regulations and re-joining the Paris Climate accords (indeed, the latter is a vital necessity), any support for natural gas is a disaster. Oil and gas companies have been pushing natural gas as a greener alternative to coal, but it turns out that when you account for methane leaks, it's just as bad in climate terms, if not worse (because methane is 28-36 times more effective than carbon dioxide at trapping heat). Unless carbon capture can be worked out — which would require standing up a multi-trillion-dollar giant industrial complex based on tentative demonstration projects — natural gas must be extirpated as a fuel source.

Whereas the Green New Deal supported by progressive democrats like Alexandria Ocasio-Cortez and Rashida Tlaib starts with a science-based goal and works out policies to get there, Biden simply assumes that whatever is roughly in the middle of the political road (as he defines it) is the best, as so-called moderates are always doing. By this blinkered ideology, the Green New Deal is simply wrong by definition. In a way, Biden's approach is akin to climate denial — not of the science, but of its obvious implications.

So why is Biden doing so well with Democratic voters — who agree climate change is one of the most important issues in the 2020 campaign — if he is plainly not up to the task of tackling the most severe problem that has ever threatened the U.S.? Jonathan Chait points to his popularity among Democrats as proof that the party's move to the left has been badly overstated. "Perhaps it was the party’s intelligentsia, not Biden, that was out of touch with the modern Democratic electorate."

There is surely some truth to this. Most Democrats are not card-carrying Democratic Socialists of America members, and many have a great deal of affection for the Wall Street bailout artist Barack Obama.

However, Chait omits a significant part of what's going on. Biden's support is pretty clearly rooted in the perception that he will be the strongest candidate against Trump. Fully 40 percent of Democrats say winning in 2020 is more important than a candidate agreeing with them on the issues. When the Progressive Change Campaign Committee polled their members, co-founder Adam Green found that "[b]arely a majority of Biden’s own current supporters believe he would be the best Democratic president."

It's true that most Democrats are not socialists. But they are still fond of Bernie Sanders, who scores 78 percent approval among party members. What they are above all is frightened and confused. They despise Trump, desperately want him out of office, and think Biden is the safest choice.

As Alex Pareene writes, this attitude has been trained into the Democratic base by several generations of party leadership, who are firmly convinced that the electorate is much more conservative than it really is. People like Nancy Pelosi and Steny Hoyer see George McGovern and 1972 behind every blade of grass and conclude that things like the Green New Deal can never pass in the U.S. — which conveniently fits right in with their alignment with major corporate interests and big dollar donors.

Despite the "safe" choice backfiring spectacularly in 2016, many Democrats are doubling down. The result might well be a nominee who will fail in our last real chance to meet the challenge of climate change.