The Earth as an extrasolar planet: The vegetation spectral signature today and during the last Quaternary climatic extrema

Abstract

The so-called Vegetation Red-Edge (VRE), a sharp increase in the reflectance around $700nm$, is a characteristic of vegetation spectra, and can therefore be used as a biomarker if it can be detected in an unresolved extrasolar Earth-like planet integrated reflectance spectrum. Here we investigate the potential for detection of vegetation spectra during the last Quaternary climatic extrema, the Last Glacial Maximum (LGM) and the Holocene optimum, for which past climatic simulations have been made. By testing the VRE detectability during these extrema when Earth's climate and biomes maps were different from today, we are able to test the vegetation detectability on a terrestrial planet different from our modern Earth. Data from the Biome3.5 model have been associated to visible GOME spectra for each biome and cloud cover to derive Earth's integrated spectra for given Earth phases and observer positions. The VRE is then measured. Results show that the vegetation remains detectable during the last climatic extrema. Compared to current Earth, the Holocene optimum with a greener Sahara slightly increases the mean VRE on one hand, while on the other hand, the large ice cap over the northern Hemisphere during the LGM decreases vegetation detectability. We finally discuss the detectability of the VRE in the context of recently proposed space missions.

31-page manuscript, 12 figures, accepted for publication in Int. J. of Astrobiology

References in corpus (3)

• Theoretical Limits on Extrasolar Terrestrial Planet Detection with Coronagraphs
• Biomarkers in disk-averaged near-UV to near-IR Earth spectra using Earthshine observations
• Earthshine observation of vegetation and implication for life detection on other planets - A review of 2001 - 2006 works

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