CNN's climate crisis town hall

California Sen. Kamala Harris said if elected president, she would back abolishing the filibuster if Republicans stand in the way of legislation to combat climate change.

It’s the first time she has said as a 2020 candidate that she backs the end of the filibuster.

Harris said she would first seek to work with the GOP.

Democrats need to win the presidency and gain three seats in the Senate to take control of the chamber in the 2020 elections. But the party would need 60 votes -- virtually an impossibility given the map of Senate seats up for election next year -- to win a filibuster-proof majority. That means even if a Democrat is elected president and the party wins full control of Congress, Republicans would still have the ability to block legislation in the Senate unless the filibuster is done away with.

California Sen. Kamala Harris' town hall just started. She's the third 2020 Democrat to take the stage tonight.

Seven more presidential candidates will have town halls later tonight.

Most of the debate over climate change focuses on fossil fuels, but meat consumption is a big driver of global warming too.

Andrew Yang, asked about how to shape habits around meat, acknowledged vegetarianism is better for the planet – but said the government can’t force anyone to stop eating meat.

What’s the impact of meat production? There's a lot for environmentalists to hate about beef. It's cattle ranchers, encouraged by Brazilian President Jair Bolsonaro, setting fires in the Amazon to destroy rain forest in order to make room for more meat production. But there is also the matter of methane produced by cows. Livestock is responsible for more than 14% of greenhouse gas emissions — and beef in particular is responsible for 41% those. 

Democrats are proposing a shift to “sustainable” agricultural practices, but Republicans have mocked a line cut from a Democratic summary of the Green New Deal that mentioned “cow farts” and allege that Democrats want to take away Americans steaks and hamburgers.

Democratic presidential candidate Andrew Yang explained on Wednesday why he supports combating climate change by investing heavily in unproven technological advancements like cloud seeding.

Cloud seeding is a technology that has been around for years, but its ability to combat climate change is more speculative. The practice involves spraying chemicals into the atmosphere to make it rain or snow, a practice that could help with extreme drought.

Yang said on Wednesday that “all solutions have to be on the table.”

“We’re here together because we can this is a crisis,” Yang said. “If you were attacking on one side, you should be researching various alternatives on the other. That, to me, is just responsible management and responsible leadership.”

Yang’s website says that he, as president, would “invest in any idea that has the potential to reverse the damage done to the environment.”

Businessman Andrew Yang said that is he's elected president, he'll eliminate gross domestic product as a measure of national success and "upgrade" it to a score card that includes environmental factors.

"As your president, I will go down the street to the Bureau of Economic Analysis and say, 'Hey, GDP, 100 years old, kind of out of date.' Let's upgrade it with a new score card that includes our environmental sustainability and our goals — the carbon footprint that companies are putting out there. But also our kids' health, which is tied to the climate, health and life expectancy, also tied to the climate, mental health and freedom from substance abuse, all things we can tie to our economic measurements," he said.

At least one other country already has a similar system. Bhutan, the tiny Buddhist kingdom wedged between China and India, is driven by a policy of Gross National Happiness.

That system takes into account every citizen's mental health and job satisfaction, bans smoking and plastic bags nationwide and refuses to develop almost half of their pristine wilderness.

But some context: Bhutan is a homogenized society with the population of Seattle. 

CNN's Wolf Blitzer just asked Andrew Yang if he supports a carbon tax.

"I do support a carbon tax — if you went to my website, Wolf, you would know this," Yang said as the audience laughed.

Yang said his carbon tax would start at $40 per ton, and go up to $100 per ton.

How does a carbon tax work, anyway? Many people think the most effective way to drastically cut carbon emissions would be to set a price on them — essentially, to tax them. 

In 2010, Democrats in the House of Representatives passed a so-called "cap and trade" bill. It would have capped carbon emissions for businesses and forced emitters to buy credits for emissions from other businesses — that’s the trade part — but it never went anywhere in the Senate.

Democratic presidential candidate Andrew Yang defended his plan to move Americans living in low lying areas to higher ground on Wednesday.

Asked about the plan by a New York resident who lives at sea level, Yang said he would “100% make funds available” to move people to higher ground and pay for it by ending fossil fuel subsidies.

“Now it’s time to take some of that money and channel it to the needs of the American people,” Yang said. “There are already climate refugees in the United States of America, people that we relocated from an island that was essentially becoming uninhabitable in Louisiana and we moved those people.”

Yang has not shied away from this position and brought it up during CNN’s Democratic debate in July.

“We need to do everything we can to start moving the climate in the right direction, but we also need to start moving our people to higher ground,” Yang said at the debate. “And the best way to do that is to put economic resources into your hands so you can protect yourself and your families.”

Businessman Andrew Yang just took the stage in New York for CNN's climate crisis town hall.

He's the second of 10 2020 Democrats to take questions at the event.

Democratic presidential candidate Julián Castro just took a question from CNN's Chief Climate Correspondent Bill Weir.

"You propose setting aside half of American land and oceans for wildlife for biodiversity. Where does that come from?" Weir asked

Casto said the US needs to "undo the damage that this administration has done" — and then "expand the lands that we're protecting in our country."

Casto said his climate plans calls for preserving more lands. Here's how he put it:

Weir said Castro's policy is in line with with the "half earth" theory of renowned biologist E.O. Wilson — that theory says that to preserve life as we know it, half of the planet must be returned to the wild.

But the federal government already owns around 30% of US land, Weir said. And Casto's vague answer did not lay out where the other 20% of hopeful wilderness would come from.