A glacier functions as an archive. Each year's layer of snow traps traces of substances from the atmosphere, so the core is effectively a calendar of both climate and pollution. Scientists cut it into sections corresponding to five-year periods, cleaned them thoroughly to avoid cross-contamination, and measured in the laboratory the minute traces of mercury at concentrations on the order of parts per trillion (ppt). CSIC / madri+d ↗
According to the authors, the earliest human emissions likely came from the smelting of copper and tin ores and from the use of cinnabar, i.e., mercury sulfide — a red mineral prized in antiquity both as a pigment and as a medicine. Archaeologists have also found elevated mercury levels in bones from ancient burial sites on the Iberian Peninsula. Infobae ↗
The pollution curve then rises sharply. In the 13th century, the accumulation of mercury in the ice increased 2.7-fold; from 1840 onward — with the onset of industry — it jumped as much as 7.4-fold. In doing so, scientists were able to separate the human signature from natural fluctuations caused by major volcanic eruptions, such as Iceland's Laki in 1783 or Alaska's Novarupta in 1912. CSIC / madri+d ↗
"We usually think humans have been polluting the planet for only a few centuries, but this new research shows that in the case of mercury, we are talking about millennia," says the study's lead author, Ari Feinberg of the Blas Cabrera Institute of Physical Chemistry at Spain's national research council, CSIC. Infobae ↗
A more precise picture of ancient emissions is not merely an academic curiosity. It is meant to help track compliance with the Minamata Convention — an international treaty against mercury that has been in force since 2017 — and to improve models that predict how quickly ecosystems can recover once emissions are curbed. Science Advances ↗
