In a recent study published in Current Biology, researchers from the Weizmann Institute of Science and Smith College delved into the fascinating questions of how much life has existed on Earth and how much life the planet may host in the future. By examining primary production, which involves the uptake of approximately 200 billion tons of carbon annually, the study estimated that 100 quintillion tons of carbon have been processed through primary production since the inception of life. The investigation also explored the history of primary producers and identified that, despite their later appearance, land plants likely contributed the most. By extrapolating current primary productivity levels, the study projected that around 10 nonillion cells exist today, with an estimated 10 duodecillion cells having existed throughout Earth’s history. Looking toward the future, the research considered Earth’s limited biosphere lifespan, projecting that approximately 10 duodecillion cells will occupy the planet until its eventual transformation into a lifeless rocky entity in about two billion years. The study concludes by proposing Earth as a benchmark for comparing life on other exoplanets and speculating on the alternate trajectories that could have shaped Earth’s diverse biological history.
