Edward Schwieterman: Challenges for advanced life in the habitable zone and implications for the search for life in the Universe

Assistant Professor of Astrobiology in the Department of Earth and Planetary Sciences at the University of California at Riverside (UCR).

Edward Schwieterman

Dr. Schwieterman employs computational methods, including climate, photochemical, and spectral models, to better understand the atmospheric composition, evolution, and remote signatures of terrestrial planets. He maintains an active interdisciplinary research group, including collaborations with geochemists, microbiologists, planetary scientists, and astronomers. His research aims to advance our ability to fingerprint authentic signs of life on exoplanets by identifying potential biosignatures and technosignatures and separating them from their possible false positives (abiotic planetary processes that mimic signs of life). He has also advanced work suggesting that the interplay between planetary climate, carbon cycling, and chemistry may limit the size of the habitable zone where advanced life could be found, with implications for the search for intelligent life beyond Earth.

Edward Schwieterman's professional web-site

Abstract: The habitable zone is typically defined as the circumstellar region where a planet with a CO2-H2O greenhouse could maintain stable surface liquid water, an essential requirement for all known life. However, substantially more CO2 than in Earth’s modern atmosphere is required to maintain clement conditions in most of the habitable zone (HZ), up to over 10,000 times more at the HZ’s outer edge. At these high concentrations, CO2 is known to be a toxic gas for many large O2-respiring organisms (humans and other animals) and would have a substantial impact on ocean chemistry (pH). Coupled with differences in atmospheric chemistry predicted for planets orbiting M dwarf stars, which would facilitate the accumulation of biosignature and toxic gases, the habitable zone real estate where technological civilizations could originate and thrive may be more limited than commonly assumed. I will present modeling results that illuminate these challenges, which also suggest the appearance of intelligent life is not necessarily dependent on random evolutionary steps but—at least in part—related to the co-evolution of the planet and its host star. I will close by discussing the implications of this work for the search for biosignatures and technosignatures beyond the solar system.

Edward Schwieterman's professional web-site