Two Thousand Years of Methane

It wasn't the Industrial Revolution that marked the beginning of greenhouse gas production, after all, according to new research findings out of the Netherlands.  Bypassing the reality that greenhouse gas production is also a natural by-product of nature, time and elemental degradation of organic matter. 

But the kind of greenhouse gas attributed to human activities, according to a study recently published in the journal Nature, began several millennia ago in ancient human history.

"Per capita they were already emitting quite a lot in the Roman Empire and Han dynasty", said lead study author Celia Sapart of Utrecht University in the Netherlands.  "When we do future climate predictions we have to think about what is natural and what did we add.  We have to define what is really natural", she said.

"The pre-industrial time was not a natural time for the climate - it was already influenced by human activity."

Professor Sapart's team of researchers are questioning the findings of the UN panel of climate scientists convinced that the surge in use of fossil fuels during the Industrial Revolution fuelled man-made climate change.  Methane, according to these new findings was likely released during deforestation in the clearing of land for farming.

The early discoveries by humankind learning how to smelt metal to fashion weapons, using charcoal as fuel in the process, likely also released methane.  Deforestation rates "show a decrease around AD 200, which is related to drastic population declines in China and Europe following the fall of the Han Dynasty and the decline of the Roman Empire", wrote the scientists.

The scientists, from the Netherlands, Switzerland, Denmark, the U.S. and France found a rise in methane coinciding with a warm period from 800 to 1200 in Medieval times, a time when Europe's economy began staggering out of the Dark Ages.  Population growth in Asia and Europe may have caused greater farming-required deforestation, once again.

A third rise in methane levels is connected with the beginning of a cooling period, the 1500s, the Little Ice Age, after having fallen because of a population decline as a result of the Black Death sweeping Europe.  After the plague, population numbers recovered and human activities once again initiated another course of rising greenhouse gases.

The evidence of these occurrences have been taken from ice cores in Greenland that provide a year-by-year environmental record in layers of compacted snow, of methane concentrations.