Oxygen Levels in the Early Earth’s Atmosphere

“Lack of oxygen did not hold back evolution of complex life” was the bold announcement in the scientific news media on January 26, 2016. An opportunity is never lost by the secular media to trumpet as supposed fact the latest scientific findings that so confidently promote the secular, naturalistic, evolutionary worldview of life’s history in a uniformitarian framework and timescale for earth’s history. This time it was all about the earth’s early atmosphere supposedly being devoid of enough oxygen to fuel the later-claimed evolution of “complex” animals from earlier “simple” life. So what was really found? Does it really show the earth’s early atmosphere was devoid of oxygen? And how does this relate or fit with what God’s Word teaches about the earth’s earliest history when He created everything fully formed and functioning in six literal days?

The Evolutionary-Uniformitarian “Story” About Earth and Life History

To answer these questions, we first need to review the evolutionary-uniformitarian “story” about the earth’s history and the claimed naturalistic development of life on earth to understand what secular scientists believe about how the atmosphere gained its present oxygen content.

Evolutionary geology thinking maintains that when the earth condensed in a hot molten state from the solar nebula about 4.6 Ga (billion years ago) it had no ocean and no atmosphere. As the earth subsequently cooled and outgassed, lots of steam condensed and collected to eventually form the first ocean waters, even by about 4.0 Ga according to the latest claimed evidence. Yet there was supposedly only a rudimentary atmosphere to begin with, dominated by gases such as water vapor, carbon dioxide, methane, and ammonia, with virtually no free oxygen. In fact, it is claimed that in the so-called Archean and earliest Proterozoic before 2.3 Ga, that is, for the earth’s first 2.3 billion years, atmospheric oxygen was likely less than 0.001% of present atmospheric levels (PAL).

Such claims about the makeup of the earth’s early atmosphere are based on indirect evidences, which are interpretations of chemical analyses of sedimentary rocks in today’s world. As such, these interpretations are being made by using assumptions about the unobserved past based on what is observed in the present.

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