A survey of mountaineers’ observations of global warming effects in the Hex River mountains, South-Western Cape, South Africa

Abstract

This study explores the changing climate of the Hex River mountains, a prominent mountain range in the south-western Cape in South Africa, over the last thirty to fifty years (1972-1992-2022). This mountain range is notable for its steep gradients and historical snow cover and related snow sports. The purpose of this study was to garner the observations of a mountain user group in South Africa regarding the impacts of global warming on the mountain range, in particular the high altitude zone between c.1800 and 2249masl, where snow, of varying texture and hardness, occurs during the winter. The literature that has been published on the mountain range’s climate indicates severe storms, and related danger, during the winter months as well as indications that the climate is changing. It also appears from previous research that geomorphic processes are increasing due to unexpected summer rainstorms, with resulting debris flow and rockfall. Fire frequency and water shortage appear to be increasing in the summer months. The methodology comprised a questionnaire which included a map of the mountain range and information on particular topoclimates. An appeal was sent to members of the mountain user group in the Western Cape; respondents were selected according to their experience of, and frequency of, visits to the mountain range. Those respondents with an education in atmosphere science were emphasised. Accounts of historical subalpine meteorology (including historical storm events) were derived from journals of the mountain user group. Personal photographs were scanned for environmental changes and two were selected to show changes in snow cover. The results indicated that water supply in summer is becoming more marginal. Other results are that there are differences regarding global warming between the windward and leeward sides, and south- and north-facing slopes of the mountain range. In addition, global warming appears to be changing altitudinal zones, especially of the temporary cryosphere that exists during the winter months. Recommendations included amending routes to avoid eroded sections and possible rockfall for people traversing the mountain range.