Who gets to control the Earth’s thermostat?

In this episode of Moonshot Radio, host Linda Du speaks with Luke Iseman, founder of Make Sunsets, a startup experimenting with solar geoengineering by releasing reflective particles into the stratosphere to cool the planet.

Luke’s work has ignited global debate about ethics, governance, risk, and radical action in the face of climate collapse. This conversation goes deep into the science, philosophy, and urgency behind a technology many consider taboo.

Themes:

• Solar geoengineering explained

  How releasing sulfur dioxide (SO₂) into the stratosphere mimics volcanic eruptions to reflect sunlight and reduce global temperatures.

• From science fiction to startup reality

  How Termination Shock inspired Luke to investigate geoengineering—and why scientific consensus existed long before public action.

• Why entrepreneurs act when institutions stall

  The tension between academic caution, government inaction, and founder-led experimentation in an accelerating climate crisis.

• Cloud seeding vs. stratospheric aerosols

  The difference between traditional cloud seeding (using silver iodide) and high-altitude aerosol reflection, and why Make Sunsets chose the latter.

• Regulation (or lack thereof) in the stratosphere

  Why international airspace law remains unresolved above ~20km, and what Luke learned from engineers who worked on Project Loon.

• Cooling credits & climate economics

  How Make Sunsets sells “cooling credits” directly to individuals, why governments and corporations have been slow to engage, and what this reveals about carbon markets.

• Carbon markets, fraud & moral hazard

  A critical look at voluntary carbon credits, including findings that large portions may be ineffective or fraudulent.

• Public backlash & political controversy

  From scrutiny by the Environmental Protection Agency to reactions from climate activists and regulators.

• Is geoengineering playing God?

  Why Luke argues that everything we already do, from flying planes to burning fossil fuels, is geoengineering, just in the wrong direction.

• Scaling planetary infrastructure

  What it would take to meaningfully cool the planet, from balloon launches to military-grade deployment by G20 nations.

• Other frontier climate ideas

  Including space-based sunshades like those proposed by the Planetary Sunshade Foundation, nuclear power revival, and climate-aligned AI infrastructure.

• Activism, blockchain & coordination at scale

  Reflections on movements like Extinction Rebellion, DAOs, crypto-enabled coordination, and what GameStop-style collective action could mean for climate.

• Work, automation & post-scarcity futures

  Drawing on ideas from David Graeber, including critiques of “bullshit jobs” and what people might build if survival wasn’t the constraint.

• Immigration, innovation & global growth

  Why openness to migration, experimentation, and building may matter more than any single technology.

This episode doesn’t offer easy answers, but it confronts the uncomfortable reality that not acting may be the most dangerous choice of all.