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Summary Continued

Summary Continued

Paleoproterozoic era

The atmospehere was mostly nitrogen. Most microscopic organisms were anaerobic. Photosynthesizers took in CO2 and let out Oxygen as waste. This changed the entire biosphere and altered the face of the planet.

Anaerobic organisms were dying off and the photosynthetic life flourished. Large amounts of oxygen entered the atmosphere. The climate changed DRASTICALLY. These organisms took up so much CO2, which is a greenhouse gas. With so much gone, temperatures began to plumet. Temperatures dropped so much that a global glaciation occured. Event known as Huronian Glaciation.

Spanned from 2.5 million years ago to 1.6 million years ago

Summary of Climate, Atmosphere, and Organisms

Only 2-3% of Earth was dry land, the rest was ocean full of iron. Due to all the iron the oceans were green, due to rust. Iron Reacted with hydroxides, and elements like sulfer and chlorine. Covering much of the world in green rust.

"The causality between the Paleoproterozic Great Oxidation Event (GOE) and a global “snowball Earth” glaciation has remained unresolved due to an inability to determine their relative timing".

"Two billion years ago, marine sulfate concentrations were around one-third as high as modern ones, constituting an oxidizing capacity equivalent to more than 20% of that of the modern ocean-atmosphere system".

Extra Facts

"Increasing oxidation dramatically changed Earth’s surface, but few quantitative constraints exist on this important transition"

"Blättler et al. found this by analyzing a remarkable evaporite succession more than 1 billion years older than the oldest comparable deposit discovered to date. These quantitative results, for a time when only more qualitative information was previously available, provide a constraint on the magnitude and timing of early Earth's response to the Great Oxidation Event 2.3 billion years ago".

"The evaporite minerals robustly constrain marine sulfate concentrations to at least 10 millimoles per kilogram of water, representing an oxidant reservoir equivalent to more than 20% of the modern ocean-atmosphere oxidizing capacity. These results show that substantial amounts of surface oxidant accumulated during this critical transition in Earth’s oxygenation".

Citations

C. L. Blättler et al. ,Two-billion-year-old evaporites capture Earth’s great oxidation.Science360,320-323(2018).DOI:10.1126/science.aar2687

https://www.pbs.org/video/that-time-oxygen-almost-killed-everything-cnzweg/