Nav: Home

Human activity has polluted European air for 2,000 years, study finds

May 31, 2017

WASHINGTON, DC -- A new study combining European ice core data and historical records of the infamous Black Death pandemic of 1349-1353 shows metal mining and smelting have polluted the environment for thousands of years, challenging the widespread belief that environmental pollution began with the Industrial Revolution in the 1700s and 1800s.

The new study, accepted for publication in GeoHealth, a journal of the American Geophysical Union, provides evidence that the natural level of lead in the air is essentially zero, contrary to common assumptions. The research shows lead pollution from mining and smelting was detectable well before the Industrial Revolution and only when the Black Death pandemic halted those activities did lead in the air return to natural levels.

"These new data show that human activity has polluted European air almost uninterruptedly for the last ca. 2000 years," the study's authors write. "Only a devastating collapse in population and economic activity caused by pandemic disease reduced atmospheric pollution to what can now more accurately be termed 'background' or natural levels."

The new findings could affect the current standards for lead pollution. Current public health and environmental policy deem pre-industrial lead pollution levels to be "natural" and thus presumably "safe," but this assumption may need to be re-examined, according to the study's authors.

Lead is one of the most dangerous environmental pollutants and is toxic to the brain at extremely low levels. No levels of lead can be considered safe in children, according to Philip Landrigan, Dean of Global Health for the Icahn School of Medicine at Mount Sinai Medical Center in New York, who was not connected to the new study.

"It's clear that lead has lasting effects on children's lives," said Landrigan, who has researched lead poisoning in children and was instrumental in the implementation of abatement policies in past years.

Reconstructing past lead levels

In the new study, historians at Harvard University in Cambridge, Massachusetts, collaborated with climate scientists at the Climate Change Institute at the University of Maine in Orono. The team chose to examine past lead levels in the air because it is a dangerous pollutant and serves as a proxy for economic activity, ramping up when economies grow and tailing off when they decline.

The researchers matched new, high-resolution measurements of lead in an ice core taken from a glacier in the Swiss/Italian Alps with highly detailed historical records showing that lead mining and smelting activity plummeted to nearly zero during the plague pandemic years of 1349 to 1353.

The researchers found that lead levels declined suddenly in a section of the ice core corresponding to that four-year window of time. That decline is unique in the last 2,000 years of European history, according to Alexander More, a historian at Harvard and lead author of the new study.

"When we saw the extent of the decline in lead levels, and only saw it once, during the years of the pandemic, we were intrigued," More said. "In different parts of Europe, the Black Death wiped out as much as half of the population. It radically changed society in multiple ways. In terms of the labor force, the mining of lead essentially stopped in major areas of production. You see this reflected in the ice core in a large drop in atmospheric lead levels, and you see it in historical records for an extended period of time."

The researchers also found other, lesser, drops in lead accumulation in the ice core. One occurred in 1460, which the authors show may have also been due to an epidemic-related downturn. Other drops occurred during an economic slowdown in 1885 and most recently in the 1970s when abatement policies phased out leaded gasoline and other sources of lead air pollution.

More said the ice core holds much additional data, accessible due to the precision of the Climate Change Institute's next generation laser facility and the expertise of climate scientists on the research team. Combining that data with historical sources can lead to new discoveries in the fields of climate science, the history of human and planetary health, environmental and economic history, he said.

"This research represents the convergence of two very different disciplines, history and ice core glaciology, that together provide the perspective needed to understand how a toxic substance like lead has varied in the atmosphere and, more importantly, to understand that the true natural level is in fact very close to zero," said Paul Mayewski, Director of the Climate Change Institute at the University of Maine and co-author of the new study. "Using the ultra-high resolution ice core sampling offered through our W. M. Keck Laser Ice Facility, we expect to be able to offer new insights, previously unattainable with lower-resolution sampling, into the links between climate change and the course of civilization."
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing 60,000 members in 137 countries. Join the conversation on Facebook, Twitter, YouTube, and our other social media channels.

Notes for Journalists

This research article is open access. A PDF copy of the article can be downloaded at the following link:

Journalists and PIOs may also order a copy of the final paper by emailing a request to Lauren Lipuma at Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release is under embargo.


"Next generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: insights from the Black Death"


Alexander F. More: Initiative for the Science of the Human Past and Department of History, Harvard University, Cambridge, Masssachusetts, U.S.A. and Climate Change Institute, Sawyer Environmental Research Building, University of Maine, Orono, Maine, U.S.A.;

Michael McCormick: Initiative for the Science of the Human Past and Department of History, Harvard University, Cambridge, Masssachusetts, U.S.A.;

Nicole E. Spaulding, Michael J. Handley, Elena V. Korotkikh, Andrei V. Kurbatov, Sharon B. Sneed, Paul. A. Mayewski: Climate Change Institute, Sawyer Environmental Research Building, University of Maine, Orono, Maine, U.S.A.;

Pascal Bohleber: Climate Change Institute, Sawyer Environmental Research Building, University of Maine, Orono, Maine, U.S.A. and Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany;

Helene Hoffmann: Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany;

Christopher P. Loveluck: Department of Archaeology, University Park, School of Humanities, University of Nottingham, Nottingham, United Kingdom.

Contact information for the authors:

Alexander F. More:, +1 (617) 417-5608

American Geophysical Union

Related Climate Change Articles:

The black forest and climate change
Silver and Douglas firs could replace Norway spruce in the long run due to their greater resistance to droughts.
For some US counties, climate change will be particularly costly
A highly granular assessment of the impacts of climate change on the US economy suggests that each 1°Celsius increase in temperature will cost 1.2 percent of the country's gross domestic product, on average.
Climate change label leads to climate science acceptance
A new Cornell University study finds that labels matter when it comes to acceptance of climate science.
Was that climate change?
A new four-step 'framework' aims to test the contribution of climate change to record-setting extreme weather events.
It's more than just climate change
Accurately modeling climate change and interactive human factors -- including inequality, consumption, and population -- is essential for the effective science-based policies and measures needed to benefit and sustain current and future generations.
Climate change scientists should think more about sex
Climate change can have a different impact on male and female fish, shellfish and other marine animals, with widespread implications for the future of marine life and the production of seafood.
Climate change prompts Alaska fish to change breeding behavior
A new University of Washington study finds that one of Alaska's most abundant freshwater fish species is altering its breeding patterns in response to climate change, which could impact the ecology of northern lakes that already acutely feel the effects of a changing climate.
Uncertainties related to climate engineering limit its use in curbing climate change
Climate engineering refers to the systematic, large-scale modification of the environment using various climate intervention techniques.
Public holds polarized views about climate change and trust in climate scientists
There are gaping divisions in Americans' views across every dimension of the climate debate, including causes and cures for climate change and trust in climate scientists and their research, according to a new Pew Research Center survey.
The psychology behind climate change denial
In a new thesis in psychology, Kirsti Jylhä at Uppsala University has studied the psychology behind climate change denial.

Related Climate Change Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".