Where does most of earths oxygen come from today?
singleAnswer
photosynthesis
Oxygen cycle Oxygen
Where does most of earths oxygen come from today?
Oxygen cycle Geological history of oxygen Oxygen Great Oxidation Event Atmosphere of Earth Supercontinent Atmosphere of Mars Atmospheric methane Carbon dioxide in Earth's atmosphere Snowball Earth
<b>Oxygen is</b> one of the <b>most</b> abundant elements on Earth and represents a large 
portion of each main reservoir. By far the largest reservoir of <b>Earth&#39;s oxygen is</b>&nbsp;... Before photosynthesis evolved, <b>Earth&#39;s</b> atmosphere had no free <b>oxygen</b> (O2). 
Photosynthetic ... At <b>current</b> rates of primary production, <b>today&#39;s</b> concentration of 
<b>oxygen</b> could be produced by photosynthetic organisms in 2,000 years. ... 
Aerobic metabolism <b>is more</b> efficient than anaerobic pathways, and the presence 
of <b>oxygen</b>&nbsp;... <b>Oxygen is</b> the chemical element with the symbol O and atomic number 8. It <b>is</b> a 
member of the ... <b>Oxygen is</b> the <b>most</b> abundant chemical element by mass in the 
<b>Earth&#39;s</b> ... At the <b>current</b> rate of photosynthesis it <b>would</b> take about 2,000 years to 
... Jump up to: <b>Derived</b> from mmHg values using 0.133322 kPa/mmHg; ^ Jump up 
to:&nbsp;... The Great Oxidation Event (GOE), sometimes also called the Great <b>Oxygenation</b> 
Event, <b>Oxygen</b> Catastrophe, <b>Oxygen</b> Crisis, <b>Oxygen</b> Holocaust, or <b>Oxygen</b> 
Revolution, <b>was</b> a time period when the <b>Earth&#39;s</b> atmosphere and the shallow 
ocean experienced a rise in <b>oxygen</b>, ... A chronology of <b>oxygen</b> accumulation 
suggests that free <b>oxygen was</b> first&nbsp;... The atmosphere of Earth <b>is</b> the layer of gases, commonly known as air, that 
surrounds the ... The three major constituents of <b>Earth&#39;s</b> atmosphere <b>are</b> nitrogen, 
<b>oxygen</b>, and ... sulfur dioxide (SO2) may be <b>derived</b> from natural sources or from 
industrial air ... The thermosphere <b>is</b> the second-<b>highest</b> layer of <b>Earth&#39;s</b> 
atmosphere. In geology, a supercontinent <b>is</b> the assembly of <b>most</b> or all of <b>Earth&#39;s</b> continental 
blocks or ... According to the modern definitions, a supercontinent <b>does</b> not exist 
<b>today</b>. ... It <b>is</b> thought that the <b>Earth&#39;s oxygen</b> content has risen in stages: six or 
seven steps that <b>are</b> timed very closely to the development of <b>Earth&#39;s</b> 
supercontinents. The atmosphere of <b>Mars is</b> the layer of gas surrounding <b>Mars</b>. It <b>is</b> primarily 
composed of carbon dioxide (95.32%), molecular nitrogen (2.6%) and argon (1.9
%). It also contains trace levels of water vapor, <b>oxygen</b>, carbon monoxide, 
hydrogen and other noble gases. The atmosphere of <b>Mars is much</b> thinner than 
<b>Earth&#39;s</b>. ... If there <b>is</b> no chemical production of CO2, all the CO2 in the <b>current</b> 
Martian&nbsp;... Atmospheric methane <b>is</b> the methane present in <b>Earth&#39;s</b> atmosphere. 
Atmospheric methane ... <b>Oxygen did</b> not become a major part of the atmosphere 
until photosynthetic ... A senior UN official and co-author of the report, Henning 
Steinfeld, said &quot;Livestock <b>are</b> one of the <b>most</b> significant contributors to <b>today&#39;s</b> 
<b>most</b> serious&nbsp;... Carbon dioxide (CO 2) <b>is</b> an important trace gas in <b>Earth&#39;s</b> atmosphere. It <b>is</b> an 
integral part of ... The present concentration <b>is</b> the <b>highest</b> for 14 million years. ... 
The production of free <b>oxygen</b> by cyanobacterial photosynthesis eventually led to 
the ... The longest ice core record <b>comes from</b> East Antarctica, where ice has 
been&nbsp;... The Snowball Earth hypothesis proposes that during one or <b>more</b> of <b>Earth&#39;s</b> 
icehouse climates, ... Since <b>today&#39;s</b> atmosphere <b>is oxygen</b>-rich (nearly 21% by 
volume) and in contact with the oceans, it <b>is</b> not possible to ... Evidence for such 
melting <b>comes from</b> evidence of glacial dropstones, geochemical evidence of 
climate&nbsp;...
photosynthetic organisms
Geological history of oxygen