![\"Example](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2025\/12\/image_14440-Mesoproterozoic-Air.jpg\")
<\/p>\nResearchers have found ancient gases and fluids trapped in 1.4-billion-year-old halite crystals from northern Ontario, Canada. Their analyses directly constrain Mesoproterozoic (1.8 to 0.8 billion years ago) oxygen and carbon dioxide concentrations to 3.7% modern levels and 10 times preindustrial levels, respectively. The results show this was a period of equable climate and that atmospheric oxygen concentrations, at least transiently, surpassed the metabolic requirements of early animals long before their emergence.<\/p>\n
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Example photographs of primary, mixed, and secondary halite inclusion assemblages. Image credit: Park et al., doi: 10.1073\/pnas.2513030122.<\/p>\n
Scientists have long known that fluid inclusions in halite crystals contain samples of the early Earth\u2019s atmosphere.<\/p>\n
But teasing accurate measurements out of those inclusions has proven to be a formidable challenge: they contain both air bubbles and brine, and gases like oxygen and carbon dioxide behave differently in water than they do in air.<\/p>\n
\u201cIt\u2019s an incredible feeling, to crack open a sample of air that\u2019s a billion years older than the dinosaurs,\u201d said Rensselaer Polytechnic Institute graduate student Justin Park.<\/p>\n
\u201cThe carbon dioxide measurements we obtained have never been done before,\u201d said Rensselaer Polytechnic Institute\u2019s Professor Morgan Schaller.<\/p>\n
\u201cWe\u2019ve never been able to peer back into this era of the Earth\u2019s history with this degree of accuracy. These are actual samples of ancient air!\u201d<\/p>\n
The readings show that the Mesoproterozoic atmosphere contained 3.7% as much oxygen as there is today, a surprisingly high number, high enough to support the complex multicellular animal life that wouldn\u2019t arise until hundreds of millions of years later.<\/p>\n
Carbon dioxide, meanwhile, was 10 times as abundant as it is today \u2014 enough to counter the \u2018faint young Sun\u2019 and create a modern-like climate state.<\/p>\n
One question that naturally arises: if there was enough oxygen to support animal life, why did it take so long to finally evolve?<\/p>\n
\u201cThe sample captures just a snapshot of geologic time,\u201d Park said.<\/p>\n
\u201cIt may reflect a brief, transient oxygenation event in this long era that geologists jokingly call the \u2018Boring Billion\u2019.\u201d<\/p>\n
\u201cIt was an epoch of Earth\u2019s history marked by low oxygen levels, widespread atmospheric and geologic stability, and scant evolutionary change.\u201d<\/p>\n
\u201cDespite its name, having direct observational data from this period is incredibly important because it helps us better understand how complex life arose on the planet, and how our atmosphere came to be what it is today.\u201d<\/p>\n
Previous indirect estimates of carbon dioxide during the period pointed to lower levels incompatible with other observations showing that there were no significant glaciers during the Mesoproterozoic Era.<\/p>\n
The team\u2019s direct measurements of high carbon dioxide levels, combined with temperature estimates from the salt itself, suggest that the Mesoproterozoic climate was milder than previously thought \u2014 comparable to today\u2019s.<\/p>\n
\u201cTed algae arose right around this point in the Earth\u2019s history, and they remain a significant contributor of global oxygen production today,\u201d Professor Schaller said.<\/p>\n
\u201cThe relatively high oxygen levels could be a direct consequence of the increasing abundance and complexity of algal life.\u201d<\/p>\n
\u201cIt\u2019s possible that what we captured is actually a very exciting moment smack in the middle of the Boring Billion.\u201d<\/p>\n