Satellites reveal air pollution from the world’s largest copper mines

Satellite observations highlight nitrogen oxide emissions coupled with copper production 

 

Copper plays a crucial role in the global transition to a sustainable economy, serving as a key component in electric vehicles, solar panels, and wind turbines. However, copper mining also poses environmental and social challenges that must be addressed responsibly. Assessing the mining industry's performance and environmental impact is essential for tracking progress toward sustainable development.

 

A new study, published in Environmental Research Letters, utilizes satellite observations of nitrogen dioxide (NO₂) to estimate nitrogen oxide (NOx) emissions over 14 of the world’s largest open-pit copper mines. The monitored sites include major copper mines in the United States, Chile, Peru, Mexico, and Zambia. The emissions mostly originate from the diesel-powered mobile fleet operating over the mines. The highest emissions were observed at the Morenci copper mine in Arizona, USA. The study found that NOx emissions are rising at many sites, particularly in South America. In contrast, emissions in the Zambian mines appear to be declining, likely due to increased electrification of mining equipment. The emissions increase with increasing copper production and moved material volumes.

With growing pressure for the mining industry to align with environmental, social, and governance (ESG) principles, independent monitoring is crucial. “Currently, most sustainability reporting in the mining sector relies on self-disclosures by companies, which can be inconsistent and incomplete. Satellite observations provide an independent, timely, and transparent way to track emissions,” explains Dr. Iolanda Ialongo, senior researcher and lead author of the study.

Satellite observations can also detect sudden changes in mining operations, such as shifts in fossil fuel usage due to fleet electrification, thereby supporting emission reduction strategies. Satellite-based assessments are especially valuable in regions lacking other monitoring systems, offering actionable data for environmental authorities, non-governmental organizations, and local communities.

REFERENCE 
Ialongo I., Virta H., Hakkarainen J., Özcan C., Ranta M., and Zieleniewski S. (2025): Unveiling nitrogen oxide emissions from open-pit copper mines through satellite observations, Environ. Res. Lett. 20 034041 https://doi.org/10.1088/1748-9326/adb767

Linear Integrated Mass Enhancement

I’m pleased to share that our paper, “Linear Integrated Mass Enhancement: A method for estimating hotspot emission rates from space-based plume observations,” has been published in Remote Sensing of Environment.

In this paper, we propose a new methodology for plume inversion emission estimation termed linear integrated mass enhancement (LIME). As the name implies, this approach is based on the integrated mass enhancement (IME) method and on the linear relationship between IME and the distance from the source. The proposed approach accounts for the information coming from different portions of the plume, and it can be seen as a “combination” of the cross-sectional flux (CSF) method and IME. The method offers a straightforward way to estimate the source strength by determining the slope of the linear fit.

We test the LIME approach with both real (OCO-3, S5P/TROPOMI, Sentinel-2) and simulated (MicroHH, SMARTCARB) satellite data. We apply the method to the simulated carbon dioxide (CO2) observations for the upcoming CO2M mission over the Matimba and Jänschwalde power stations with known source rates. We use the OCO-3 data to estimate the CO2 emissions originating from the Bełchatów power station in Poland (between 72 and 103 ktCO2/d). We also estimate the emissions from two methane (CH4) leaking sites in Algeria based on S5P/TROPOMI (77 and 47 tCH4/h for two days) and Sentinel-2 (7.7 tCH4/h) observations. Finally, we apply the LIME method to the Sentinel-2 retrievals from a controlled CH4 release in Arizona.

Across all case studies, the LIME emission estimates are in agreement with the expected values. The LIME estimates are also aligned with the state-of-the-art IME emission estimates, which are calculated as byproducts in the LIME emission estimation process.

Citation:

Janne Hakkarainen, Iolanda Ialongo, Daniel J. Varon, Gerrit Kuhlmann, and Maarten C. Krol: Linear Integrated Mass Enhancement: A method for estimating hotspot emission rates from space-based plume observations, Remote Sensing of Environment, Volume 319, 2025, https://doi.org/10.1016/j.rse.2025.114623.