To reconstruct the history of the great civilizations, archeologists and historians study traces of materials that these peoples left in their wake, and the texts that they wrote his contemporaries. The field work in archaeological sites and excavations, the finding of objects and the verification of written sources -the roman Republic already knew of the fake news – provide the necessary keys in this task. In recent years, in addition, the climate science has become an unexpected ally for researchers, providing a new clue to reconstruct the vicissitudes of the great empires of the past: their ecological footprint.
beyond the military power of the legions, the greatness of Rome was built on its economic wealth, with the official currency -the denarius – as a cornerstone. So, most of the emissions during this historical period were the result of the extraction and smelting of lead and silver, from the mines of the iberian peninsula. So that the levels of contamination by these metals serve as an excellent indicator of the financial health during the Republic and the Empire. Now, a multidisciplinary team made up of archaeologists, historians, chemists, and hydrologists – have been able to trace the rise and fall of Rome, thanks to evidence found under the ice of Greenland, with 4,600 kilometres of the Palatine hill.
The investigation covers from the year 1100 to.C. up to 800 of our era and has been recently published in the journal ‘Proceedings of the National Academy of Sciences’. The work points to a first increase of the amount of lead from the NINTH century to.C., coinciding with the decline of the metropolis of phoenicia, and the expansion of Carthage. In the 218 to.C., for example, with the end of the Second Punic War, pollution suddenly drops and then see a spike, which marks the moment when the roman soldiers to take control of the mines carthaginian of Andalusia and put into operation.
Pollution from the mines of Spanish
But the deposits geological peninsular, which provided the necessary raw material for minting coins that circulated throughout the roman world, were not producing pure silver, in its place desenterraba a mineral containing silver, lead and copper and that needed to be cast. This whole process would relieve a certain amount of pollution by heavy metals, which, once in the atmosphere, accumulating in the clouds and traveled with them to points as far distant as the Arctic. “Places like Greenland are cold enough as to not produce almost no melting at the surface, which prevents the loss of anything, once deposited there”, explained Andreas Stohl, a scientist at the Norwegian Institute for Research on Air and co-author of the research. “This allows you to obtain records very high resolution”.
New layers of snow and ice were burying the remains of lead for millennia, hidden until, in 1990 climate scientists danes began to study the floor. “The ice at that point is very thick -almost 3 km of depth – so the layers of snow accumulated are thick and ancient,” says Joe McConnell, a professor at the Institute of Desert Research (DSI) and the principal author of the work, “the ice fund has up to 100,000 years old”.
end of the Republic to the fall of the Empire
The analysis of these levels of emissions allows to identify moments of expansion and crisis in the roman economy, confirming events documented, which include wars, conquests, and pests. According to records, the work of casting reached its peak in the first stage of the Empire, especially during the Pax Romana (between the year 27 d.C and the year 180 d.C) and a recorded production levels that would not be matched until 500 years after. On the other hand, the events related to the crisis of the Republic, marked by executions and political civil wars, show a broad period of stagnation and disintegration and economic, according to the study.
“During the first two centuries of the Empire, the emissions are nearly four times higher than in the last decades of the Republic,” says the historian of the University of Oxford Andrew Wilson, “which reflects substantial economic growth under the imperial domination”. The archaeologists have also found evidence of events not violent: for example, in the 64 d.C Rome devalued its currency, reducing the amount of silver in pence, which is reflected in a slight decrease in the pollution in the following years. A century later, in the 165 d.C, a plague spread from the east throughout the roman world for more than 15 years. Known as Peste antonina, ended the lives of millions of people and devastated the army. The levels of emissions in the atmosphere fall markedly at this point and never to approach the figures of the first empire.
Step forward of the climate science
The authors explain that a study with this level of detail has only been possible thanks to improvements in the models, computerized of the atmosphere, developed significantly in the last decades with the monitoring of climate change. In addition, chemists and hydrologists have also refined their ability to discover traces of metals and minerals in ice cores. In this case, the researchers have studied three blocks, which were to be drilled, extracted and stored in the 90’s, and have been melted by means of pads, heating special. “Each record implies an average of 60 individual measurements carried out in a continuous stream of water melting during a period of approximately 9 seconds,” explains McConnell.
During these last few years, scientists of all fields have collaborated to develop comprehensive records of weather events are important, which also allows to take into consideration times in which the emissions increase in a natural way, as for example as a consequence of large volcanic eruptions. On the other hand, the scientists in this field have taken a step forward in its ability to link precisely each one of these records to a specific date, providing, unwittingly, a new tool to unravel the secrets of the Story.
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