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Rwenzori Ice Dynamics and Environmental Changes

Periodic Reporting for period 1 - RIDEC (Rwenzori Ice Dynamics and Environmental Changes)

Reporting period: 2015-09-07 to 2017-09-06

At the border between Uganda and the D.R. of Congo, the Rwenzoris (0.386°N; 29.872°E) form a remote and high-altitude mountain range stretching near the equator, through the East African Rift System. With heights of 4-5 km, they include Africa's third highest peak (Mt. Stanley, 5109 m) as well as some of the last African glaciers. The combined area of the Rwenzori glaciers declined by more than 80% during the 20th century, and halved between 1987 and 2006. This extreme mass loss may have strong implications for the local ecosystems and communities, and recent estimates suggest that the glaciers will disappear in the next decade(s). This trend correlates well with similarly dramatic glacier retreats on Mt Kilimanjaro (TZ) and Mt Kenya (KE) in the same period, and is attributed to debated causes like increased air temperature or reduced humidity/cloud cover. Despite recent work on the evolution of glacier extent in the last decades, the measured glacier retreat, as well as the interpretation of the responsible driving climatic factors, remain controversial partly owing to the lack of data.

In order to better understand the dynamics of this recession, a detailed survey of the current state of the two largest Rwenzori glaciers, Stanley and Speke glaciers, was made using a panel of remote sensing, geophysical and geochemical methods. These included, first, satellite-based monitoring of glacier extents over the last decades, mapping of the current glacier extent and main features using differential GPS, and assessing the glacier thicknesses using ice-penetrating radar. Second, a weather station data recording main climatic parameters was installed in the glacier vicinity in order to better understand the glacier sensitivity to the changing climate. These results were compiled with a view to provide a first estimate of modern, past and future ice budgets in the area of interest.

Given the limited expected time period before Rwenzori glaciers disappear entirely, the RIDEC project represented a unique opportunity to investigate, before they melt completely, the invaluable body of information retained in them.
Work performed under the RIDEC project encompassed three major aspects:

1. Field expeditions in the Rwenzori Mountains (Uganda/D.R. Congo)

a) Glacier mapping
Two field parties were organized in 2016 and 2017 during which scientific research and geographical exploration about Rwenzori glaciers were carried out. The boundaries of the two most important glaciers were mapped by means of GPS in order to monitor the evolution of the glacier extents. These present-day glacier contours provided a frame of reference for comparison with other types of archive data acquired by remote sensing in the last decades, such as aerial photographs or satellite images.

b) Climate
Two autonomous research instruments powered by solar energy, namely a weather station and a time-lapse camera, were set up in the upper glacier zone of the Rwenzori Mountains in order to better understand the climatic drivers for glacier down-wasting in the region. Data recovered from these instruments constitute unique archives of high-altitude, glacier environments in tropical Africa.

c) Mass balance
A network of bamboo stakes was drilled with a mechanical auger at the surface of Stanley Glacier in order to monitor the amount of ice removed from the glacier surface by melting. Together with climatic and aerial/satellite data, these mass balance data allowed to perform a detailed analysis of glacier volume evolution over the last decades.

d) Ice thickness
Various types of ground-penetrating radars were used to evaluate the thickness of Stanley and Speke Glaciers. These data are essential for, first, reconstructing present-day glacier volume and, second, for investigating glacier evolution dynamics in the past or in the future.

2. Computer-based reconstruction of glacier and climate dynamics

a) Satellite/aerial imagery
Various types of archives were compiled from selected topographic records and ancient aerial photos available. Rwenzori glacier boundaries were reconstructed between the early 20th century period and the late 1950’s by means of these image archives.
Satellite optical imagery was also compiled from various space agency repositories, focusing primarily on long-term data available from public domains. Glacier contours were digitally mapped from these various sources for the period covering the mid 1980’s to the present day.
Finally, use was made of the various types of imagery datasets described above to reconstruct the topography of main Rwenzori glaciers over several time periods, from which the temporal evolution of glacier volume changes could be calculated.

b) Ice Flow Modelling
No information is currently available on the potential ages of Rwenzori glaciers. Data acquired from our climatic, geophysical and mapping studies were compiled and integrated into ice flow models in order to better understand the dynamic evolution of Rwenzori glaciers during recent warming climate. This task is essential for building scenarios of glacier evolution in the near future.

3. Conferences and capacity building
Different kinds of activities, such as training courses, conferences or workshops, were organized or attended to foster informal science education on the hand, and dissemination of research findings on the other hand. Various kinds of audiences were targeted, ranging from kids and students in classrooms to specialized researchers at international conferences. Exchange activities were also organized with involved local communities, institutions and stakeholders in Uganda.
1. Scientific impacts
During this project, not only were glacier extents monitored for the last years through field work mapping, but also were they reconstructed for the last decades through detailed remote sensing, GIS and photogrammetrical analysis. Specific trends of glacier recession dynamics were distinguished for the Rwenzori Mountains, which allowed us to provide a clear overview of ice budget evolution in the last >100 years.

2. Societal impacts
One efficient way to share information about research, and therefore to foster informal science education, is to make it accessible to the people directly involved in the research topic. The Rwenzori people were first targeted in this case. Exchange workshops were organized in Nyakalenjija (Uganda), the village located at the entry point to the Rwenzori National Park, and in Fort Portal (Uganda), where the Mountains of Moon University is having its campus.

By promoting environmental research and engaging with citizens, the RIDEC project also received public attention in Europe through numerous TV, radio, newspapers interviews and through interactions with various public audiences. Several millions of people in Belgium and elsewhere were exposed to matters related to African glaciers and climate change in this way.
Mass balance measurements on Stanley Glacier, Rwenzori - Samyn D. 2016