No Change in Black Carbon Levels on Peruvian Glaciers, Despite Pandemic Quarantine

12 May 2020

Published by https://glacierhub.org/

PERU – GlacierHub recently contacted Wilmer Sanchez Rodriguez, a Peruvian glaciologist who has worked for a number of years in the Cordillera Blanca. He is actively engaged in measuring the deposition of black carbon in that range. In the interview below, he explains the research program. We asked him whether there was evidence of a decline in black carbon after a strict quarantine, beginning on 15 March, was imposed on Peru. His preliminary findings indicate that the levels of black carbon in March and April were low, but not exceptionally low. These months fall during the rainy season when precipitation removes black carbon from the atmosphere; the prevailing winds in this season are largely from the Amazon, a region of low population density, rather than from the more densely settled highland and coastal regions.

GH: Please explain to our readers the work of American Climber Science Program. 

WSR: The American Climber Science Program (ACSP) is made up of a group of scientists, volunteers and climbers, who collect field data in mountainous environments (for example, the Andes, the Himalayas). The work consists of collecting data and samples annually, in order to assess the impact of glacier on the mountain ecosystems. Among the data, water samples are particularly important, since they indicate the concentration of heavy metals that derive from glacier beds; also of importance are data on soil quality, biodiversity, vegetation cover, the concentration of black carbon on the glaciers.

Since 2011, the ACSP has conducted annual expeditions during the dry season of May to October in the Cordillera Blanca. Topics include long-term monitoring of the effects of pollution on glaciers, impacts on quality and water quality, assessing the effects of climate change (changes in temperature and precipitation) on the structure of the ecosystem (plant communities and their distribution), the function of the ecosystem (soil nitrogen and carbon cycles), identification of sources of pollution and mitigation options.

GH: How long have you been working with this program?

WSR: In 2014 I was part of the ACSP expeditions in the Cordillera Blanca. My particular interest was always studying glaciers from a more local point of view. One of the scientists (Dr. Carl Schmitt) collected snow sample. After melting and filtering the snow, I observed how the soot produced in nearby cities and in the environment of the mountains was deposited on the snow, I was impressed with the impact of the black carbon particles (soot) on the glaciers and from that moment I knew that this would be the research project for my studies as an environmental engineer. In September 2014, we started a monthly monitoring of black carbon in the glaciers of the Cordillera Blanca. At present, we have the longest record of black carbon in the Andean glaciers.

GH: What are the activities you have done during the current Covid-19 pandemic? What types of samples do you obtain, in which places, how often and with what methodology? 

WSR: Despite the restrictions on movement and travel during the quarantine, I can fortunately access the glaciers without contacting anyone and thus continue to collect snow samples.

Our mission is to assess the effect of confinement and the stoppage of human activities on the deposition of black carbon on the glaciers of the Cordillera Blanca. Thanks to a research grant from the American Alpine Club we are developing a study called “The impact of black carbon on the melting of Vallunaraju glacier,” a glacier that is popular with Peruvian and international climbers, and that is located near Huaraz, the largest in the region. The study lasts for one year (April 2019 to April 2020), and involves measuring black carbon in snow, calculating the radiative forcing of black carbon on snow, estimating the amount of snow that melts at it causes black carbon, the formation of cryoconite holes and their relationship with black carbon, and the modeling of the atmospheric transport of pollutants to the glacier.

Our sample unit is the recently fallen snow that covers the glaciers, since the solar radiation hits it directly. Depending on the level of pollution, it will reflect or absorb solar energy. We collect snow in both the accumulation and ablation zones of the glacier. As of September 2014, Yanapaccha and Shallap glaciers were monitored on a monthly basis. In 2017 Tocllaraju and Vallunaraju glaciers were added to the monitoring, alternating the monitoring between glaciers. Later in 2018, the monthly monitoring of the Yanapaccha and Shallap glaciers was resumed, this under the supervision and financing of the National Research Institute for Glaciers and Mountain Ecosystems (INAIGEM), and in 2019 the Vallunaraju glacier joined the monitoring (thanks to the AAC grant). This choice of glaciers permits us to test the hypothesis that glaciers closer to Huaraz (the main source of contaminants) have higher concentrations of black carbon than more distant glaciers.

Sample analysis uses the Light Absorption Heating Method (LAHM), as we described recently in an article in The Glaciologist. Black carbon particles are captured in a quartz filter, and exposed to visible light. The particles absorb light and as a result increase the temperature. The temperature increase is directly related to the mass in the calibration filters and allows an estimation of the mass of black carbon. For the calculation of radiative forcing we use the SNICAR model, which allows us to estimate the reduction of snow albedo with the presence of black carbon. And to model atmospheric transport we use NOAA’s HYSPLIT model.

GH: If you have any preliminary results, please describe them; if not have now, please indicate the date when you expect to have them.

WSR: In general, our results show that the deposition of black carbon on these glaciers on the western flank of the Cordillera Blanca on the western flank is greater during the dry season (May-October, non-monsoon), compared to the wet season (monsoon), where higher atmospheric moisture and precipitation significantly reduce black carbon deposition on glaciers. Likewise, the glaciers closer to the city of Huaraz have a greater amount of black carbon throughout the year, compared to the glaciers furthest from the mountain range. In turn, the deposition of black carbon is inversely proportional to the altitude, that is, the higher the altitude in the glacier, the lower the amount of black carbon.

We witnessed the first row of the impact of the El Niño (2015-2016) and El Niño Costero (2017) phenomena on the glaciers of the Cordillera Blanca. It is well known that El Niño causes abundant rainfall on the Peruvian coast (above the normal average). However, in the high mountains, it has the opposite effect, the dry months (without rains) are prolonged, the precipitation falls as rain rather than snow due to the elevation of the isotherm, and clear days are common. As a result, there is more solar radiation, forest fires increase, and the snow line rises above 5000 meters. The concentrations of black carbon on the glaciers of the Cordillera Blanca during El Niño in 2015-2016 reached similar values ​​to the most polluted glaciers in the Himalayas, with 1047.07 ng/g and 1091.75 ng/g (ng/g = nanogram of black carbon per gram of snow), on Yanapaccha and Shallap glaciers, respectively. In early 2017, the sea surface temperature rose sharply in the region of the tropical Pacific Ocean known as Niño 1 + 2. This anomaly was called El Niño Costero, and brought abundant rainfall in the high mountains, something causing severe floods in the main coastal cities. Dominated by solid precipitation (snowfall), El Niño Costero represented a significant increase in snow on the glaciers. Likewise, with more humid months, scarcity of forest fires and cloudy days, the concentration of black carbon reached minimum values ​​of 0.63 ng/g and 1.89 ng/g in Yanapaccha and Vallunaraju glaciers, respectively. This represents snow almost as clean as snow in Antarctica. In summary, extreme events like El Niño have significant consequences (positive or negative) on the Andean glaciers.

Currently, our study in Vallunaraju glacier aims to answer several questions, among them, the impact of black carbon on the radiative forcing of snow, the amount of snow melted due to black carbon, the formation of cryoconite holes and to know the possible sources of black carbon. The preliminary results of this study (“The impact of black carbon on the melting of the Vallunaraju glacier”) suggest that black carbon contributes to melting of the glacier significantly as it accelerates the melting of seasonal snow, which would otherwise remain during the wet season reflecting the sun’s rays.

Near the end of our study (which was completed at the in April 2020), the results show a maximum concentration of 214.13 ng/g of black carbon (in a normal year – without El Niño), while a minimum of 3.73 ng/g was reached. at the end of the first month (March 2020) of mandatory confinement of people by COVID-19. This is a fairly low value despite the low snow cover on the glacier. However, it does not represent a significant change for the wet season. The change in the concentration of black carbon on the glacier would have been more evident if the quarantine Ha occurred during the dry season (May-October), when the absence of rains and a drier atmosphere favor the transport of black carbon from anthropogenic sources. Among the sources, the Hysplit model located the possible sources of black carbon in the Amazon jungle of Peru, Brazil, and Colombia in most of the months of study. Due to the trade winds that circulate from East to West, the black carbon particles generally come from the Atlantic. However, at the beginning of the wet season there are trajectories of pollutants from the Pacific. Obviously, the model represents a global circulation, it is necessary to model the local winds within the Rio Santa valley.

GH: Please give us other comments about the importance of your investigations in current circumstances.

WSR: In a context of global climate change, it is necessary to know all the contributors to the glacial retreat. Forecasts estimate an increase of 2.5 ° C in the Andean region by the end of the century, this would significantly reduce the glacier mass. Added to a higher emission of black carbon globally, it would produce a positive feedback effect.

Global models do not include the anthropogenic factor in glacial retreat. In general, the models only consider the increase in temperature, leaving aside, changes in precipitation patterns, cloud cover, the concentration of pollutants (black carbon, organic carbon, algae, dust), among others. A unified model will allow knowing the contribution of each driver of the glacial retreat, this will allow taking concrete measures to mitigate and reduce anthropogenic drivers.

Constant and prolonged monitoring of black carbon in the glaciers of the Cordillera Blanca will allow establishing a pattern of black carbon deposition at the regional level. This will permit comparisons with other regions of the cryosphere. Obviously, the arrival of COVID-19 brings environmental benefits in the different environmental ecosystems, since there is a reduction in the emissions of the different pollutants, due to the confinement of people, and glaciers are no strangers to this benefit. However, since the quarantine has fallen during the wet season, we are not able to observe a significant change in black carbon deposition on glaciers.