We seek to model the coupled evolution of a planet and a civilization through the era when energy harvesting by the civilization drives the planet into new and adverse climate states. In this way we ask if “anthropocenes” of the kind humanity is experiencing might be a generic feature of planet-civilization evolution. In this study we focus on the effects of energy harvesting via combustion and vary the planet’s initial chemistry and orbital radius.

Here we use a 3-D climate system model to study the habitability of Earth-like planets orbiting in circumbinary systems. A circumbinary system is one where a planet orbits around two stars simultaneously, resulting in large and rapid changes to both the stellar energy distribution and the total stellar energy received by the planet. We find that Earth-like planets, having abundant surface liquid water, are generally effective at buffering against these time-dependent changes in the stellar irradiation due to the high thermal inertia of oceans compared with the relatively short periods of circumbinary-driven variations in the received stellar flux. Ocean surface temperatures exhibit little to no variation in time, however land surfaces can experience modest changes in temperature, thus exhibiting an additional mode of climate variability driven by the circumbinary variations. Still, meaningful oscillations in surface temperatures are only found for circumbinary system architectures featuring the largest physically possible amplitudes in the stellar flux variation. In the most extreme cases, an Earth-like planet could experience circumbinary-driven variations in the global mean land surface temperature of up to ~5 K, and variations of local daytime maximum temperatures of up to ~12 K, on monthly timescales. Still, habitable planets in circumbinary systems are remarkably resilient against circumbinary driven climate variations.

Unidentified Flying Objects (UFOs) appear frequently in science fiction and other public depictions of extraterrestrial technology. Recent interest in understanding UFOs, also known as Unidentified Aerial Phenomenon (UAP), has increased due to a recent report published by the U.S. Department of Defense that confirmed the detection of several UAP. However, actually identifying such objects remains challenging because “sociocultural stigmas and sensor limitations remain obstacles to collecting data on UAP” according to the report. In this presentation, we discuss the challenges posed by popular conceptions of UAP to genuine scientific inquiry using examples from Carl Sagan’s archives. This discussion is intended to engage astrobiologists in thinking critically about the differences between scientific inquiry of a genuinely unknown phenomenon and non-scientific popular speculations about the identity of UAP.

The search for spectroscopic biosignatures with the next-generation of space telescopes could provide observational constraints on the abundance of exoplanets with signs of life. An extension of this spectroscopic characterization of exoplanets is the search for observational evidence of technology, known as technosignatures. Searching for technosignatures alongside biosignatures would provide important knowledge about the future of our civilization. If planets with technosignatures are abundant, then we can increase our confidence that the hardest step in planetary evolution---the Great Filter---is probably in our past. But if we find that life is commonplace while technosignatures are absent, then this would increase the likelihood that the Great Filter awaits to challenge us in the future.