Methane producing bacteria as early as 3.5 billion years ago?
Methane-emitting bacteria could have existed as early as the Archean Era 3.5 billion years ago and influenced the climate development of the planet - 700 million years earlier than previously assumed.
These paleogeological indications of such microbes were found by researchers led by Yuichiro Ueno from the Tokyo Institute of Technology in Yokohama in hydrothermally formed quartz veins in Western Australia's Pilbara craton - one of the oldest rock formations on earth and remnant of the first continents of the early Earth period. During their growth, the quartz crystals enclosed liquid bubbles that also contained the methane.
Using an isotopic analysis of the carbon present, the scientists concluded that the original source of the gas could only have been appropriate methane-producing bacteria: that was biologically produced and subsequently compared to methane originating from chemical reactions or from geotectonic sources captured gas depleted in isotope 13C.
According to the scientists, this evidence supports the thesis that methane was a significant greenhouse gas in the earth's atmosphere at that time and raised the air temperatures of the then still young planet to a level that was bearable for the beginning of life. Back then, the sun radiated less energy than it does today, so the primeval earth was rather overcooled.