When has Anthropocene begun? In other words when has humanity started changing its environment and climate? To answer this question Ca’ Foscari and Cnr scientists investigated ice and lake core records in Asia, America and Europe, and glaciers in the Alps and Himalaya.
After five years around the world seeking human traces on the environment, professor Carlo Barbante, paleoclimatologist leading the research, explains: “According to our data, anthropocene would have begun 3,000 years ago, with a peak of fires in vast areas of the Earth to allow for human settlements and agriculture”.
Anthropocene has been dated up to the beginning of the Industrial Revolution by some researchers. For the paleoclimatologist William Ruddiman the new era would have begun up as early as 7,000 years ago, associating human activity with an abnormal increase of carbon dioxide in the atmosphere. Barbante’s team rejected this hypothesis, showing that the increase of greenhouse gas of 9-7 thousand years ago is not due to human causes but to natural ones.
A few thousand years later as fires generated a major increase of carbon dioxide the impact what completely different: “The impact was strong and at times irreversible on the environment, but localized and not global, contrary to current records” explains professor Barbante.
The cases of New Zealand and Central America are significant: in the first instance, islands were dramatically deforested by polynesian colons from 1,300 b.C., forever changing their environment. Almost at the same time Mayas used the technique of slash-and-burn, increasing the dry period and laying the foundations for the crisis of their own civilization.
How can scientists reconstruct millennia old fires, human settlements and climate change? The new analytical methods developed by the Early Human Impact project funded by the European Research Council allowed Barbante’s team to retrace a molecule in ice caps, the levuglucosan, produced by biomass burning. Furthermore scientists found traces of molecules in human feces proving human presence in lake settlements. Combining these evidences enables researchers to distinguish between natural and human caused fires.