Last night's "Climate Town Hall" on CNN wasn't just long (seven hours!). It was deeply revealing about how Democratic presidential candidates think about government's power to regulate virtually all aspects of human behavior and how they approach policy and cultural change.

The Democratic contenders have laid out plans costing anywhere from about $1 trillion (Pete Buttigieg) to $16 trillion (Bernie Sanders) in direct federal spending on climate change over the next decade. About half of the candidates have endorsed the Green New Deal proposed by Rep. Alexandria Ocasio-Cortez (D–N.Y.) and Sen. Ed Markey (D–Mass.), which could cost as much as $90 trillion to implement. As important as any specific policy or position outlined last night were the general attitudes that were widely shared by the participants.

A number likened fighting climate change to the effort to win World War II, a metaphor that perhaps says more about their comfort with regimenting society than the speakers intended. During World War II, all industrial production was overseen by the federal government, food and fuel were rationed, and civil liberties were sharply curtailed in the interest of defeating the Axis powers.

In a related way, the candidates all bought into the apocalyptic premises of the questioners, who took for granted the idea that the world is likely to end in a decade or so unless massive, transformational change takes place. The resulting conversations were thus long on the need for action and short on the need to build consensus or to fully assess the costs and benefits of particular actions.

Here are four memorable moments involving the leading candidates:

1. Joe Biden: Here's Blood in Your Eye.

Whatever the former vice president and Delaware senator actually said last night will forever be a footnote to the fact that his left eye apparently filled with blood during his time on the stage, leading Hot Air's Allahpundit to suggest that "individual Biden body parts are now generating their own gaffes."

The bloody eye won't help a campaign that has been plagued with questions about the 76-year-old's mental and physical health, but the less we remember about what Biden actually says on the campaign trail, the better. Indeed, the nation's only fully satisfied Amtrak rider had barely started talking when he announced, "We can take millions of vehicles off the roads if we have high-speed rail." That's a callback to President Barack Obama's high-speed rail plans, which went nowhere even when the Democrats controlled the White House and Congress. There's simply no reason to believe that high-speed rail will ever be successfully built in America (California alone has spent a decade and billions of federal, state, and local tax dollars while making effectively zero progress on its high-speed rail project)—and even if it does get built, there's little reason to expect it to yield meaningful environmental benefits.

2. Elizabeth Warren: "We only have 11 years to cut our emissions in half." So let's…stop using nuclear power?

Sen. Elizabeth Warren (D–Mass.) famously has a plan for everything. While the former Harvard Law School prof sidestepped questions about whether the government would continue to dictate what light bulbs Americans can buy (so that's a yes), she stressed that we've "got, what, 11 years, maybe, to reach a point where we've cut our emissions in half." In suggesting that the world will end in 2030 unless we dramatically reduce greenhouse gas emissions, Warren is invoking Ocasio-Cortez's stunning misreading of a 2018 Intergovernmental Panel on Climate Change report. Far from declaring that the planet would soon be fried, the report theorizes that, as Reason's Ronald Bailey writes, "if humanity does nothing whatsoever to abate greenhouse gas emissions, the worst-case scenario is that global GDP in 2100 would be 8.2 percent lower than it would otherwise be."

Whether or not such a projection is reliable, Warren clearly believes in the 2030 apocalypse. That makes the stance she took last night against nuclear power puzzling, since nuclear is much cleaner than fossil fuels or coal. "In my administration, we won't be building new nuclear plants," she said. "We will start weaning ourselves off nuclear and replace it with renewables." Which is to say, she's in line with many progressives (including Bernie Sanders, Ed Markey, and AOC), who say simultaneously that the world is ending but nuclear power should remain off the table, even as they push "solar panels, [which] produce 300 times more waste for the amount of energy created than do nuclear plants," according to environmentalist researcher Michael Shellenberger. Staring down a supposed existential threat, Warren and her anti-nuke allies still have principles, or something.

Sen. Elizabeth Warren: "The fossil fuel industry… want[s] to be able to stir up a lot of controversy around lightbulbs, around your straws, and around your cheeseburgers when 70% of the pollution of the carbon that we're throwing into the air comes from 3 industries." pic.twitter.com/DhQXbLJO3P — The Hill (@thehill) September 5, 2019

3. Bernie Sanders: Aggressively fighting the phantom menace of global overpopulation.

A teacher at the town hall said world population was growing beyond the planet's carrying capacity and asked Bernie Sanders the following:

"Empowering women and educating everyone on the need to curb population growth seems a reasonable campaign to enact. Would you be courageous enough to discuss this issue and make it a key feature of a plan to address climate catastrophe?" "Well, Martha, the answer is yes," Sanders said.

Bernie backs using taxpayer money to fund abortions in other countries to control population growthhttps://t.co/hoiwrDS1YV pic.twitter.com/waIdk2Y3Di — RNC Research (@RNCResearch) September 5, 2019

Pro-life right-wingers are hot and bothered over the Vermont senator's willingness to support taxpayer-supported birth control, including abortions, in his quest to defeat climate change. For those of us who believe in female autonomy and reproductive rights, that's far less troubling than watching him buy into the idea that global overpopulation is in any way a problem.

As the folks at Our World in Data note, "global population growth reached a peak in 1962 and 1963 with an annual growth rate of 2.2%….For the last half-century we have lived in a world in which the population growth rate has been declining." The United Nations has changed its projections for population growth; it now even suggests a 27 percent chance that global population will peak and start to decline by 2100. And there's this:

Demographer Wolfgang Lutz and his colleagues at the International Institute of Applied Systems Analysis (IIASA) believe that the United Nations' projections are likely to be too high. In their 2018 demographic assessment, IIASA calculates a medium fertility scenario that would see world population peak at 9.8 billion people at around 2080 and fall to 9.5 billion by 2100.

If worries about the world ending by 2030 are overstated, so too are fears of a planet that can't support its population, especially given the incredible strides we've recently made in reducing global poverty and increasing general living standards.

4. Kamala Harris: "I think we should" ban plastic straws.

"Plastic straws are a big thing right now," said CNN's Erin Burnett to Kamala Harris. "Do you ban plastic straws?" "I think we should, yes," replied the California senator, who then proceeded to laugh uneasily as she said paper straws were not very good.

The moral panic about plastic straws exemplifies how discussions of environmental issues go off the rails. As Reason's Christian Britschgi revealed in January 2018, the erroneous idea that Americans used 500 million straws a day was based on a school project done in 2011 by a nine-year-old boy in California. America in fact contributes only a small portion of the world's plastic pollution problem, and straws represent just a tiny fraction of that. And yet by the end of last year, plastic straws were "an endangered species" around the country due to outrage over a made-up number.

But Harris wasn't simply trash-talking plastic straws. She also spent time attacking the eating of red meat, calling for the end of land sales for oil and gas drilling, and pledging to end fracking, the very technology that helped lower U.S. greenhouse gas emissions to record-low levels.