Former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE has a 9-point lead over Sen. Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.) among climate-focused voters, according to a new poll released Wednesday by the Sierra Club.

Biden wins 30 percent support in the polls, followed by Warren at 21 percent and Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE (I-Vt.) at 20 percent in the tracking poll conducted by Morning Consult.

It's the same result Biden had in the last poll conducted in July, while it shows a slight increase for Warren from 20 percent, and a larger increase from Sanders who had 16 percent support in the previous survey.

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California Sen. Kamala Harris Kamala HarrisTexas Democratic official urges Biden to visit state: 'I thought he had his own plane' The Hill's Campaign Report: Biden on Trump: 'He'll leave' l GOP laywers brush off Trump's election remarks l Obama's endorsements A game theorist's advice to President Trump on filling the Supreme Court seat MORE (D) saw the biggest decrease in support from "climate voters," falling 6 percentage points from 13 percent to 7 percent since the previous tracking poll.

At the time the poll was conducted, Harris was one of two candidates who had not yet released a climate-focused policy plan. Her campaign released an outline for her $10 trillion climate plan early Wednesday morning.

South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBillionaire who donated to Trump in 2016 donates to Biden The Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice MORE also released his stand-alone climate action plan Wednesday.

The results largely mirror other national polls that have had Biden in the lead, trailed by Warren and Sanders.

While Biden’s climate plan has been chastised by some environmentalists for not going far enough, the results indicate voters think otherwise.

The climate action plans from the three front-runners all vow to invest several trillions of dollars into transitioning the U.S. towards a renewable and clean electric grid, yet they all differ by timeline and methodology. Whether a candidate embraces nuclear energy in his or her plans has come out as one defining point.

CNN will host the first presidential forum focused entirely on climate change Wednesday night. MSNBC will hold another Democratic primary forum on the issue later this month.

In addition, the poll found that 90 percent of likely Democratic voters supported a transition to clean and renewable energy sources by 2030. The poll also found that 68 percent of likely voters support holding a climate debate, in addition to the two forums.