> over geological timeframes, the plant life they contain is the reason we have any oxygen to breath About 1/2 of the oxygen produced is produced by Phytoplank

> over geological timeframes, the plant life they contain is the reason we have any oxygen to breath About 1/2 of the oxygen produced is produced by Phytoplankton, which are not plants (though they are similar). > And if the amazon currently amounts to about 20% of the plant life on earth now The amazon accounts 16% of the photosynthesis on land. > its not wrong to teach that it is doing 20% of the oxygen maintaining. It is wrong. If you want to provide a nice round, reasonably accurate number you should use 10%. > does not make a lie of the understanding and respect that forests are lungs of the planet. Forests are important and and a significant part of the respiration of them planet, but they are less important than our oceans. Our oceans are the true lungs of the planet (edit: and they are not in great shape, atmospheric oxygen may not be an issue, but oxygenation of the ocean is more variable).