Beto O’Rourke

Mr. O’Rourke’s campaign said: “Yes. For example, we would be immediately considering new steps to curb super-pollutants and methane emissions.”

Tim Ryan

“Part of this is, how do we sit down as a business industry, research, environmental, public health people, and say: ‘O.K., what do we need to do here to get to where we need to be? Where do we need to be, and how do we get there, and how do we get there as fast as possible, and how do we all work together to get there?’ And so saying, ‘Hey, we’re going to put these regulations on now’ — I think it’s dangerous for us to say Democrats want to put on all these regulations, and then the Republican Congress is going to put on riders to not fund whatever you’re doing. Because we’ve been watching this happen. So how do you actually sit down with everybody and put together an agenda that we can all move forward on, and if administrations change or the House flips or the Senate flips, this is the agenda that we’ve all agreed upon? That is critically important, because this back-and-forth stuff, Obama puts it on, Trump lifts it off, riders on bills to defund things on the Appropriations Committee — it’s sand in the gears.”

Bernie Sanders

Mr. Sanders’s campaign said he would go beyond Obama-era regulations, but did not elaborate or provide an on-the-record quote.

Eric Swalwell

“I would restore all of the Obama-era regulations that the Trump administration has reversed. Once those are restored, we can continue to gauge their efficacy to decide how and where to go further.”

Elizabeth Warren

“I oppose subsidies for fossil fuel companies and have spoken out repeatedly against the influence that Big Oil and carbon-based industries wield in Washington. My Climate Risk Disclosure Act would require companies to disclose their greenhouse gas emissions and price their exposure to climate risk into their valuations, raising public awareness of how dependent companies are on fossil fuels and using market forces to speed the transition to clean energy.”

Marianne Williamson

“The Obama regulations are too incremental to turn things around in ways that are necessary. I am a supporter of Alexandria Ocasio-Cortez’s Green New Deal, which seeks to meet 100 percent of the power demand in the United States through clean, renewable and zero-emission energy sources within the next 10 years.

“I would end all subsidies for dirty energy and transfer them to subsidies for clean energy. I would prevent coal companies from using misleading marketing terms like ‘clean coal,’ and look for ways to move coal jobs to clean jobs, while closing coal plants and opening clean energy plants. I would start a phase-out of production of fossil-fuel-related vehicles. I would require zero-deforestation supply chains — that’s one of the more effective ways to help encourage healthy practices in other countries. And I would take a serious look at large agribusinesses, who are not only destroying the careers and lives of small, rural and family farmers, but doing damage to the planet in potentially irreversible ways. Multiple scholars have concluded that huge agribusinesses are the leading producer of methane gas and nitrous oxide (two of the most dangerous greenhouse gases) and are the No. 1 cause of ocean dead zones, water pollution, deforestation and habitat destruction. Compelling research suggests that even if we eliminated all fossil fuel use, we will exceed our 565 gigatons CO2e limit by 2030, simply from huge agribusinesses. There is no way to create policy around climate change without exploring ways to better regulate the waste produced by these massive companies, as well. In particular, we need to break up CAFOs (Concentrated Animal Feeding Operations), considering that even a relatively ‘small’ CAFO, with 2,500 animals, produces as much urine and feces and deadly runoff as a city of 411,000 humans.”