So does this mean there's been a significant drop in oxygen (produced)? And if so, how much?
If 100% of phytoplankton produces 50% of the oxygen and 100% is now 60% that mean 50% of oxygen is down to 30%. In other words, sans a drop in non phytoplankton, total oxygen that was 100% is not 80%?
Wouldn't we feel that?
From a different paper-
> Oxygen concentrations are currently declining at roughly 19 per meg per year, or about 4 ppm per year. One "per meg" indicates one molecule out of 1,000,000 oxygen molecules, or roughly one molecule in 4.8 million molecules of air.
You would need huge resources and deploy a really fine "mesh" of stations for a very long time to study that.
Is the job of oceanographers, and do this all the time at local small scale. But extrapolating to a global scale is a really ambitious project, prone to came with the wrong answers.
Not to mention that aren't even doing plankton taxonomy. Is a collection of secchi disks data. To point to just one of the major problems with the study, Secchi disks aren't used at night normally. Let suppose that we would visit google headquarters at 4am for example, we could wrongly assume that is a mostly deserted area. Is the same problem.