- Atmospheric escape and long-term habitability: participants explored how thermal and non-thermal loss of atmospheric gases, plus water sequestration into the mantle via serpentinization (≈6.7 × 10¹¹ kg yr⁻¹), could remove roughly half of Earth’s ocean mass within a billion years, making Earth increasingly arid.

- Mantle cooling and water absorption: discussion cited a National Science Review paper estimating subduction currently returns more water to the mantle than volcanism releases, suggesting the planet may lose surface water on the same ~1 Gyr timescale as solar expansion.

- Gamma-ray bursts as nearer-term existential risks: a nearby GRB (<6 kly) could strip the ozone layer and was proposed as a possible “1 Mya” class event, though others argued historical GRBs did not render Earth uninhabitable.

- Adam Marblestone’s influence: referenced as a futurist technologist from Boyden & Church labs, originator of the “barcode sequencing connectome” concept (arXiv:1404.5103) as a scalable alternative to electron-microscopy connectomics.

- Motivational framing: one participant noted that contemplating billion-year existential threats (atmospheric loss, solar evolution) simultaneously evokes fear and a drive toward “meaningful action” in transhumanist research and engineering.