From Ben Haller, Ithaca, New York, US
Alice Klein reports evidence that early anoxygenic photosynthesis produced so much methane that it warmed the planet by about 15°C (16 December 2017, p 11). She also notes that anoxygenic organisms exist today, photosynthesising in anaerobic environments, but they are not widespread and thus “no longer have a significant effect on Earth's climate”.
But anaerobic “dead zones” are proliferating in the oceans now and are probably increasing in size (9 December 2006, p 38). Does this mean that organisms of the sort described are due for a renaissance, thriving in this new human-made habitat? If so, has the effect of their methane production been factored into climate models?
The editor writes:
• Klein noted that anoxygenic photosynthetic organisms like green sulphur bacteria and purple bacteria cannot tolerate oxygen. But ocean dead zones tend to move around, so these organisms might only thrive if they evolved to be more tolerant.
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