Climate change will get a moment in the spotlight today when the top half of the Democratic presidential field gathers in New York City for CNN’s seven-hour forum on the topic.

For some of the candidates—such as Sen. Kamala Harris (D-Calif.) and Mayor Pete Buttigieg of South Bend, Ind.—the forum could provide a much-needed opportunity to show climate activists they have the chops to address global warming.

But all 10 candidates who qualified—from Sen. Bernie Sanders (I-Vt.) to former Vice President Joe Biden—will be forced to take potentially uncomfortable questions from CNN moderators and a live, town-hall audience. Candidates will appear in individual segments lasting about 40 minutes each.

The event also is a test of sorts for the issue of climate change itself, as it’s unclear how many voters will tune into the midweek political marathon.

The whole thing starts today at 5 p.m. EDT with former Housing and Human Development Secretary Julián Castro. A full lineup is available here.

Here are five storylines to watch:

Will the new climate plans affect the race?

There’s no motivation like a deadline, and several candidates are putting out climate plans ahead of today’s forum.

The last-minute rush includes Sen. Amy Klobuchar (D-Minn.), who dropped a proposal Sunday that would combat climate change with a tax on carbon emissions and a $1 trillion infrastructure package.

And Sen. Cory Booker (D-N.J.) released a plan yesterday that includes a carbon tax, as well as $3 trillion in climate spending and a focus on environmental justice (see related story).

Climate activists are closely watching Buttigieg and Harris, too, whose campaigns have hinted at a release soon.

So how much will this matter?

For Booker and Klobuchar, likely not much.

Both candidates are polling near the bottom of the field, and neither of their plans rank as the most ambitious in the Democratic primary—meaning that their proposals are unlikely to woo environmental voters away from climate-focused candidates such as Sanders or Sen. Elizabeth Warren (D-Mass.).

Their plans will keep them in the conversation, however, and give them a script to follow during the CNN climate forum.

Buttigieg and Harris have a bit more at stake, as both are trying to break out of the middle of the pack.

Harris in particular will be under the microscope as she initially balked at attending the forum—a slight that outraged climate activists.

story last week by Reuters hinted that Harris’ proposal would blend her support of the Green New Deal with a focus on protecting vulnerable communities from the worst effects of global warming.

Will anyone watch?

For weeks, climate activists have tried to convince the Democratic National Committee to convert one of the remaining primary debates into a discussion focusing solely on global warming.

One of their main arguments was that few people would watch a political event that wasn’t a debate—and CNN’s own ratings bear out that concern.

The two nights of debates that CNN hosted in July in Detroit attracted an average of 9.7 million television viewers per evening.

That’s several times the ratings that the network garnered for the individual town halls it held earlier this year with several of the Democratic presidential candidates. (Harris’ town hall, for example, netted about 1.4 million viewers—and that was one of the best.)

Now that the DNC has scuttled the idea of a climate-only debate, environmentalists said they are hoping their dire predictions about viewership are proved wrong.

“The climate debate stuff really went into the consciousness of Democrats who are not party insiders, who are not deep in the weeds and who are not political junkies,” said RL Miller, political director of the environmental group Climate Hawks Vote. “There is an extraordinary level of interest in this.”

Miller added: “We will see.”

Does Warren respond to Sanders?

Throughout the 2020 campaign, Sanders and Warren have competed for the liberal lane of the Democratic electorate. Few issues highlight this rivalry like their fight over climate change.

Warren has released a series of plans this year that show how she would tackle global warming, including a proposed $2 trillion investment over 10 years in “green research, manufacturing, and exporting.”

But Sanders raised the ante last month by calling for $16.3 trillion in government spending to address climate change.

Sanders, for his part, will have to explain how he would marshal the political will to turn that expensive pledge into reality—a problem that elicited a stinging rebuke recently from The Washington Post.

There’s also the question of whether Sanders would back the elimination of the filibuster, as Warren has done, to pass climate legislation.

Still, Warren has some pressure to respond to Sanders and his plan, which one notable climate activist called the “most ambitious” in the field (Climatewire, Aug. 23).

Warren, for now, appears to be taking the competition in stride.

A couple of days after Sanders rolled out his plan, her campaign posted a Twitter thread that dispassionately spelled out her multitiered approach to climate change.

“It’s going to take big ideas and bold, structural changes to achieve the goals of the #GreenNewDeal,” she wrote. “Climate change is an existential threat to all of us—and we need to act now.”

Will Biden embrace the Green New Deal?

When climate activists first proposed the Green New Deal, the idea attracted broad, bipartisan support—in part because voters still weren’t quite sure what to make of its vision of fighting climate change with a government-led jobs program.

The early spark was enough that six senators running for the White House jumped on board as co-sponsors of a resolution enshrining the plan’s goals.

Since then, the idea has lost some support, “particularly among conservative Republicans and regular viewers of the Fox News Channel,” according to polls and an analysis conducted by researchers with Yale and George Mason universities.

The idea has remained popular among liberals and Democrats, however. That dynamic could put pressure on Biden, the current front-runner.

Does he double down on his support of the plan to try and lock down the primary? Or does he keep the idea at arm’s-length in an effort to appeal to more conservative voters in a general election?

“We would love to hear more from Biden as to how he’s going to take immediate and bold action,” said Garrett Blad, a spokesman for the Sunrise Movement, the environmental group that’s championed the Green New Deal.

That includes what Biden would do to defang fossil fuel companies, he added. “We would love to see questions about that and how he would take on the industry,” Blad said.

The rollout of Biden’s climate plan in June provides some potential clues on how he might approach the Green New Deal at the CNN forum.

While supportive of some of the Green New Deal’s ideals, such as using climate change as an opportunity to create new jobs, Biden’s proposal mentions the Green New Deal by name exactly once.

Will carbon taxes get some love?

The Green New Deal, without question, has been the straw that has stirred the drink of climate politics these last few months.

But during the 2016 election, carbon taxes played a similar role—so much so that Sanders used the issue to question former Secretary of State Hillary Clinton’s commitment to fight global warming.

The lack of attention this cycle, however, doesn’t mean the idea has gone away.

Far from it.

Multiple Democratic candidates, from Biden to Buttigieg to entrepreneur Andrew Yang, have included the idea in their climate plans. Others, such as Warren and former Rep. Beto O’Rourke (D-Texas), have said they are least open to the prospect (Climatewire, July 30).

But for climate policy wonks, it won’t be enough for the candidates to simply say they support a tax on carbon emissions.

There are a whole host of questions that go into it. At what price per ton should it start? Which industries will bear the brunt? And how should the government spend the money it collects?

Some of the candidates have answered these particulars.

Former Maryland Rep. John Delaney, for example, would begin his carbon tax at $15 per ton and increase it annually by $10. He then would return the revenue to taxpayers.

But other candidates, such as Biden, have been less specific about their plans, and the CNN forum could force them to release new details.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news