Contemporary Shrinking of Colombia's Highest Mountains: Pico Simon Bolivar and Pico Cristobal Colon

2 Contemporary Shrinking of Colombia’s Highest Mountains: Pico Simón Bolivar and Pico Cristóbal Colón

Pico Cristóbal Colón and Pico Simón Bolivar are the highest peaks in Colombia and were last accurately surveyed in 1939. This historical survey measured Cristóbal Colón, Colombia’s recognized highpoint, at 5775m and Simón Bolivar at 5773m. Both peaks have permanent icecaps at their summits. For this study, multiple differential GPS units and an Abney level were used to re-survey each peak with sub-meter vertical accuracy. As of December 2024, the elevation of Simón Bolivar was 5720.42m +/- 0.08m and Cristóbal Colón was 5712.79m +/- 0.87m. These measurements indicate that the ice caps of both peaks have shrunk dramatically since 1939: Simón Bolivar by 53m and of Cristóbal Colón by 62m. Contrary to official recognition, Pico Simón Bolivar is now the highest mountain in Colombia. Increasing local temperatures suggest that the icecap melting of both peaks is due to climate change.
Keywords: climate change, glacier recession, ice-capped summit, mountain elevation loss, Sierra Nevada de Santa Marta Introduction
Colombia has six glacier masses that cover a total area of 33 square km at elevations ranging from 4800m to over 5700m. Since the early 2000s, when detailed measurements began, the extent of Colombian glaciers has been rapidly decreasing, with an average annual surface area loss rate of 3-5% (Ceballos et al 2023). According to the World Meteorological Organization, glaciers in the tropical Andes have lost 30% of their surface area since the 1980s (WMO 2022).
Although the glacial recession in Colombia has been well-documented, few recent measurements have been taken for glaciers at the highest altitudes in the country, in the coastal Santa Marta Mountains. These mountains host the highest peaks in Colombia: Pico Cristóbal Colón (Colón; location 10.838775S, 73.687191W) and Pico Simón Bolivar (Bolivar; location 10.834718S, 73.690453W; Fig. 1). These adjacent

3 summits are exceptionally prominent in the region, rising to more than 5,500 meters, and visible from long distances. In addition, both Colón and Bolivar are ice-capped summits, meaning the highest point on the peak is ice, and these icecaps are the highest- elevation glaciers in Colombia.
Ice-capped peaks around the world are at risk of climate-induced elevation loss as warming temperatures melt their summit ice (Gilbertson et al., in review). Shrinking of ice-capped summits has already been observed in many mountain ranges including the summit of Kebnekaise, the highest peak in Sweden (Holmlund and Holmlund 2018), the summit of Mt Blanc, the highest peak in France and Italy (Berthier et al 2023), and mountains in Washington, USA, including Mount Rainier, the highest peak in the region (Gilbertson et al., in review). Here, we re-surveyed the highest peaks in Colombia to determine if their ice caps have shrunk since they were last measured in 1939. We conclude by placing our results in the context of recent climate trends in the region.

Figure 1. A: Location of our focal peaks in the Santa Marta Mountains of Colombia. B: Colón (left) and Bolivar (right), viewed from the north. C: Satellite view of the peaks.

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Methodology History of Climbing and Surveying on Colón and Bolivar Bolivar was first climbed on Feb 2, 1939 by Krause, Praolini, and Pichler. Krause surveyed the summit elevation at 5520m using a hypsometer (Ruiz 1990). This measurement was later corrected by the Augustin Codazzi Geographic Institute to 5794m, though the error bounds on the measurement were not given (Ruiz 1990). In general, hypsometers can have errors up to 5-10% of absolute measured altitude (Dobyne, 1988), meaning these measurements could have been in error by approximately 250-500m.
Colón was first climbed a month later, on March 16, 1939, by Praolini, Bakewell, and Wood. This climb was part of the larger American Cabot expedition, which conducted a trigonometric survey of the area. That expedition measured Colón at 5775m and Bolivar at 5773m (Echevarria 1963). Trigonometric surveys in that time period had much lower errors, on the order of a one part per million (0.0001%) (Kershaw 2012). Thus, since 1939, Colón has been recognized as the highest peak in Colombia.
The next survey was conducted in 1989, when Von Rotkirch and Ruiz brought an altimeter to each summit and measured Colón at 5775m and Bolivar at 5790m (Ruiz 1990). In general, altimeters have much higher errors than a trigonometric survey (Dobyne 1988), so the only conclusion that can be reasonably drawn from this survey was that the peaks were of similar ele