Nearly half of the US Democratic presidential candidates cited climate change as one of the greatest threats to the nation during the debate last night, but the topic otherwise barely came up during the two-hour event.

Any presidential contender should have to answer many hard and detailed questions about how to accelerate the shift to clean energy and address the hazards we’ve already unleashed, all within a gridlocked political system.

So here are seven questions we’d put to the candidates:

1. Everyone loves wind and solar, but we’ll also likely need advanced nuclear reactors, enhanced geothermal systems, and fossil-fuel plants with carbon capture. Will you crusade for those as well?
2. Would you push for a carbon tax to accelerate the shift to clean energy—and if so, how high should it be?
3. One of the cheapest and most effective ways of enabling a larger share of renewables on the electricity grid would be to build out more ultra-high-voltage transmission lines, and more tightly integrate the nation’s regional grids. What specific steps would you take to modernize the US grid? (See “China’s giant transmission grid could be the key to cutting climate emissions.”)
4. The UN IPPC’s latest report concludes we’ll need to remove as much as a trillion tons of carbon dioxide from the atmosphere this century to limit warming to 1.5 ˚C. Will you support a major federally funded research effort to advance technological systems for sucking CO₂ out of the air, as well as stronger market subsidies to help the carbon removal sector get off the ground? (See “One man’s two-decade quest to suck greenhouse gas out of the sky.”)
5. Is it time for the government to begin funding research exploring the possibility of geoengineering the climate, through means like stratospheric aerosol injection and marine cloud brightening? (See “The growing case for geoengineering.”)
6. What will you do to help cities adapt to greater risks of flooding, droughts, hurricanes, and fires?
7. Most of the policy debate to date around climate has focused on transforming the electricity and transportation industries, but those together represent only around 57% of US greenhouse-gas emissions. What will you do to help clean up the “hard-to-solve” sectors like cement production, steelmaking, and agriculture? (See “We still have no idea how to eliminate more than a quarter of energy emissions.”)

Several energy and environment experts proposed a few additional questions when I sought suggestions on Twitter.

Joshua Rhodes of Vibrant Clean Energy:

Jeremiah Johnson, associate professor at NC State University:

Josh Busby, associate professor of public affairs at the University of Texas, Austin:

Michael Powers, founding partner of Stellar Solar:

Other climate and energy writers and thinkers have posed their own list of questions that are worth reading, including Rolling Stone’s Jeff Goodell, The Atlantic’s Robinson Meyer, and Genevieve Guenther, director of EndClimateSilence.org.