Gauging the climate movement's political clout is hardly an exact science, but I'm watching two things today that will provide some insights.

1. It's primary day in Sen. Ed Markey's race against Rep. Joe Kennedy in Massachusetts.
2. The green movement's left flank is stepping up efforts to shape Joe Biden's circle of advisers, with an array of groups releasing an open letter this morning calling for a ban on all "fossil fuel executives, lobbyists, and representatives from any advisory or official position on [Biden's] campaign, transition team, cabinet, and administration."

Why it matters: Let's start with the Senate race. Markey is among Capitol Hill's most prominent climate advocates. He co-authored the Green New Deal (GND) resolution, and a decade before that co-wrote the big climate bill that passed the House but went no further.

He's getting support from several climate groups and movement figures, including:

• Rep. Alexandria Ocasio-Cortez, who worked with Markey on the GND.
• The upstart Sunrise Movement, which helped push the GND into the political bloodstream and devoted lots of organizing resources to the race.
• Long-established green groups like the League of Conservation Voters Action Fund, the Sierra Club and the Environment America Action Fund.

Where it stands: Markey was considered the underdog heading into the race against a challenger from a family that's legendary in Bay State politics, but has held a lead in recent polling.

What they're saying: Veteran Massachusetts political consultant Mary Anne Marsh tells Politico that backing from AOC, Sunrise and Justice Democrats has changed the race.

• "That is what has allowed this remarkable makeover of Ed Markey to combat the fact he's 74 years old and been in Congress 44 years," Marsh said.
• "The way they did that was to make him the darling of the climate change warriors, and instrumental to that is ... Ocasio-Cortez."

The intrigue: Getting back to the letter to Biden, it's signed by 145 local and national groups.

• These are actors that will battle more moderate Democrats for influence if Biden wins and Democrats control Congress, such as Sunrise, Oil Change U.S., Justice Democrats, 350.org, Greenpeace and others.

The other side: The Washington Examiner has a good, detailed story about the pressure on Biden — and pushback against it. Josh Siegel reports...

"Centrist Obama administration alumni counter that it's counterproductive to impose limits on the pool of talent who can provide counsel to Biden on a complex and technical issue such as climate change."

"'The only litmus test should be that people who want to serve in the Biden administration should be 100% on board and supportive of the Biden climate agenda,' a former Obama administration official told the Washington Examiner, requesting anonymity to discuss a sensitive subject."

There are political and substantive limits to how much Biden will move his energy plans in the direction that some climate activists want, and yesterday underscored a big one.

Driving the news: Biden yesterday rebutted President Trump's claim that the Democratic nominee would seek to ban fracking, the oil-and-gas extraction method that has enabled a surge in U.S. production over the last decade.

• "I am not banning fracking. Let me say that again. I am not banning fracking. No matter how many times Donald Trump lies about me," Biden said.

Why it matters: The remarks came during a closely watched speech in Pennsylvania, a critical swing state Trump carried in 2016 where fracking-enabled natural gas development is a major industry.

• While Biden has made his plans more aggressive in recent months, he has rejected calls for an outright ban on fracking — which would require extraordinarily unlikely congressional action.
• Biden's long-standing platform aims to thwart oil-and-gas development on federal lands and waters, but it does not call for a national ban on fracking that would affect private lands, where the nation's oil-and-gas boom has been centered.

The intrigue: Biden has given Republicans an opening because his position on a fracking has been confusing at times, most notably at a March debate with Sen. Bernie Sanders when Biden said, "No new fracking."

• His campaign later claimed that Biden was restating his existing platform — not endorsing Sanders' call for a nationwide ban.
• Sen. Kamala Harris, the VP on the Democratic ticket with Biden, had previously endorsed a national fracking ban.

Biden's team has clearly decided that loudly opposing a fracking ban in a high-profile speech is the right political move. But polling in Pennsylvania shows shades of gray.

By the numbers: Multiple polls give a peek at the controversial topic in the state.

• 52% opposed fracking in a CBS News poll of registered voters last month, while 48% favored it, a finding within the poll's margin of error.

• Yesterday the Global Strategy Group released a poll of registered voters funded by Climate Power 2020, the League of Conservation Voters and the Sierra Club. It showed strong support for tougher regulations, and also 62% support for phasing out fracking by 2050 (emphasis added because that's not a "ban").
• A Franklin & Marshall College poll of registered voters in January found that "more voters support (48%) than oppose (44%) shale drilling in the state." Paradoxically, it also showed that 48% support a fracking ban while 39% oppose the idea, but the error margin is ±6.2%.
• A 2019 Kaiser Family Foundation and Cook Political Report poll released last November showed that 57% of swing voters in Pennsylvania oppose a fracking ban.

Of note: I doubt I've seen every poll on Pennsylvania and fracking, so Generate readers: Please send along other surveys that may be out there, thank you!

Wind and solar made up 67% of the new power generating capacity added worldwide in 2019, widening their gap with fossil fuels, which fell to 25%, per new data from BloombergNEF.

Why it matters: The research firm's report on power trends over the last decade shows both the fast growth of those resources and also why they remain a very small share of the overall power mix despite rapid expansion.

By the numbers: "Wind and solar accounted for over two-thirds of the 265 [gigawatts] of new capacity installed worldwide in 2019, up from less than a quarter in 2010," they find.

• On a generation basis, wind produced 6% of global power last year and solar accounted for 3%.

Yes, but: The whole pie also grew a lot. Total global power-generating capacity rose 44% since 2010 and reached 7.3 terawatts last year, BNEF said.

• Coal still has the biggest share and lots of new capacity has been added, though it's declining on a percentage basis and overall generation fell last year as plants ran less often.
• "Gas and hydro remain the second and third most popular technologies globally on a megawatts-installed basis and both continue to expand. However, they grew by just 1% from 2018-2019, the smallest rate of change in a decade," BNEF found.

Tesla was the best performing stock in the U.S. during August, rising 74.3% during the month, including a gain of 50% since announcing its stock split on Aug. 11, Axios' Dion Rabouin reports.

Check out Dion's Axios Markets newsletter here.

Renewables: "Total SE will team up with Macquarie Group’s green bank to develop more than 2 gigawatts of floating wind farms off South Korea, the latest push by the French oil and gas giant to diversify into clean energy." (Bloomberg)

Shale: "Oil and gas companies plunged over $156 billion into corporate takeovers and land deals during the second U.S. shale boom, in a massive bet that good times would continue and crude prices would rise. Many of those deals have become financial albatrosses." (Reuters)

EPA: "The U.S. Environmental Protection Agency on Monday completed a set of new guidelines for disposing of coal ash and wastewater from coal-fired power plants, changes that critics say could allow more pollutants into the nation’s waterways." (WSJ)