Soot deposits accelerate the melting of snow, ice and glaciers in many remote, still relatively pristine regions of the Earth, including the Arctic, the Himalayas or the Andes, although the sources of the soot particles are usually further away. A new study has now shown that even in the Antarctic Peninsula region, the amount of so-called “black carbon” is so high that the snow melts faster because the dark particles absorb solar radiation and heat the snow. Unlike other regions, however, black carbon here comes from local sources, i.e., activities related to research and tourism. The study, published in the journal Nature Communications, has caused an international sensation.
Snow in Antarctica is the cleanest on Earth. On the white continent, only about one nanogram of soot particles per gram of meltwater can be detected. But where activities of researchers and tourists are concentrated – in the Antarctic Peninsula area – the authors of the study found levels between three and seven nanograms of soot particles per gram of meltwater. Although black carbon levels here remain well below those of remote regions in the northern hemisphere, where around 20 nanograms of soot particles per gram of meltwater were found in the snow, the authors of the recently published study estimate a snow melt of 23 millimeters each summer – in addition to snow loss due to global warming.
For the study, which also involved scientists from the Alfred Wegener Institute for Polar and Marine Research and the University of Zurich, the researchers took snow samples in four consecutive summers from 2016 to 2020 at 28 sites from King George Island at the northern tip of the Antarctic Peninsula to the southern Ellsworth Mountains – the region of Antarctica most frequently visited by researchers and tourists.
Black carbon is produced by the combustion of diesel, coal and wood and is transported in the atmosphere over shorter or longer distances. On snow, the soot particles lower the albedo, or reflectivity, and instead absorb the sun’s rays, causing the snow to melt more quickly. However, Antarctica is largely isolated from the rest of the world due to the special, ring-shaped circulation conditions in the atmosphere (as well as in the ocean), and black carbon input from outside occurs only in very small quantities. Therefore, the comparatively high amount of soot particles detected by the authors in the area of the Antarctic Peninsula may originate predominantly from local sources. According to the study, these include, on the one hand, ships, helicopters, aircraft, vehicles and diesel generators necessary for operating research stations and conducting research projects, and, on the other hand, cruise tourism around the Antarctic Peninsula.
The study points out that human presence in Antarctica and especially around the Antarctic Peninsula has increased significantly in recent decades. In total, there are 76 active research stations in Antarctica that host about 5,500 people during the summer. About half of the stations are located on the northern Antarctic Peninsula and neighboring islands. In recent years and decades, some of the stations have developed into logistical hubs with a correspondingly high frequency of activities.
In addition, there is an increasing number of cruise ships that visit the region around the peninsula each summer. In the 2019/2020 pre-pandemic season, the IAATO (International Association of Antarctica Tour Operators) counted a total of about 74,000 tourists, most of whom traveled to Antarctica on expedition cruise ships and also took shore excursions. This is about twice as many as ten years earlier. Just over 700 tourists flew directly to the Antarctic continent, for example to Union Glacier Camp in the Ellsworth Mountains.
The team of authors estimated the snow loss caused by the input of black carbon at about 600 tons per capita per summer due to research activities, whereby only the influence of the eleven stations on King George Island with 700 beds was considered here. For the tourism sector, the authors came to about 83 tons of snow loss per capita per season. Based on a mean value of 53,000 tourists per season in the years 2016 to 2020, the authors thus estimate the total snow loss attributable to tourism around the Antarctic Peninsula at over four million tons per year, while research activities on King George Island alone are said to be responsible for 400,000 tons.
The rules that apply to all operations and activities in Antarctica to protect the environment, and which were laid down in the Antarctic Treaty, are very strict. For example, not only must all research projects pass an environmental impact assessment, but all providers of (expedition) cruises must follow a strict protocol and meet a variety of requirements, and the IAATO has in some cases tightened the rules for its members.
“IAATO [ …] aims to strengthen the management of tourism in Antarctica by also requiring its members to abide by the rules it sets, often over and above what is required by the Treaty System,” as Amanda Lynnes, director of environment and science coordination at IAATO, explicitly points out.
Additionally, tourist operators have been strictly prohibited from operating their vessels in Antarctica with heavy fuel oil for the past decade with the introduction of the heavy fuel oil ban by the International Maritime Organization (IMO). According to Amanda Lynnes, some operators are already running their ships on cleaner hybrid propulsion systems or alternative fuels. Research probably still has some catching up to do here.
In conclusion, the authors of the study highlight the urgent need to reduce black carbon inputs to Antarctica to limit this additional snowmelt. On the one hand, they demand from IAATO a faster switch to cleaner ships and a limitation of tourist activity, although Amanda Lynnes points out that IAATO has no direct influence on the latter – that is in the hands of the contracting states. But one can at least advocate and promote activities with reduced emissions, she further explains. On the other hand, national Antarctic programs would also need to reduce their footprint by, for example, adopting energy efficiency standards and generating energy from renewable sources. The Belgian station “Princess Elizabeth Antarctica” is setting a good example: it is the first emission-free research station on the white continent. And Chilean Antarctic bases are currently testing “green” energy sources.
Undoubtedly, the study aims to help protect Antarctica more effectively against pollution in the future.
Julia Hager, PolarJournal
Link to the study: Cordero, R.R., Sepúlveda, E., Feron, S. et al. Black carbon footprint of human presence in Antarctica. Nat Commun 13, 984 (2022). https://doi.org/10.1038/s41467-022-28560-w
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