Kilimanjaro: an ice-free Africa?

Over the last few posts we've seen the dramatic extent of glacier loss in the Rwenzori Mountains, affecting not only agriculture and ecosystems, but also community tourism and tribal traditions. Today, we're going to take a look at glaciers on Africa's most famed mountain: Mount Kilimanjaro.

An iconic view of Mt Kilimanjaro and it's snowy peaks (Source)

Mount Kilimanjaro, a dormant stratovolcano in Tanzania, is Africa's tallest mountain, rising nearly 20,000 ft above sea level. In recent decades, the mountain has attracted a multitude of attention, becoming a symbol for global warming in Africa (Thompson et al 2009). The reason for this is the glacial extent crowning the mountain of ~12km2 in 1912, is roughly 85% more than what exists today (extent was just 1.76km2 in 2011) (Cullen et al 2013). The famous ice-climber, Will Gadd, was shocked after arriving at the summit of Kilimanjaro last year and realising the ice he had planned to climb (from looking at photos), no longer existed (Lindzon 2015).

The ice-fields that have persisted throughout the Holocene (the last 11,700 years) are notably shrinking, and the finger is pointing towards global warming as the blame. Climate change on a global scale has the ability to locally affect Kilimanjaro due to changes in large-scale circulation systems that transport moisture to East Africa (Mölg et al 2013). In the scientific community, there is no longer of question of whether ice will disappear on the mountain, but a question of when it will all be gone. Though some uncertainty remains regarding the evolution of future precipitation patterns in East Africa, Cullen et al (2013) propose that if current trends continue, most of the remaining ice-cover on Kilimanjaro will be gone by 2040, and all ice will have sublimated and/or melted by 2060. If you can't envisage the changes to Kilimanjaro in writing, watch the video below from Cullen et al (2013) showing glacier loss from 1912 to 2011 using a 3D model with satellite imagery - very powerful!

Kaser et al (2010) argue that the primary cause of Mt Kilimanjaro's primarily sublimating glaciers is reduced atmospheric moisture, as opposed to rising air temperatures (most often associated with global warming). However, this is unlikely to be the only cause of thinning, melting and sublimating ice. A widespread drought 4,200 years ago, lasting ~300 years (recorded in a dust layer in ice cores), was not sufficient enough alone to remove the ice fields (Thompson et al 2009). Thus, it must be a complex combination of climatological factors such as warmer surface temperatures, reduced humidity and altered cloudiness, alongside terrestrial changes in land-use that are causing the loss of ice on this tropical mountain (Kaser et al 2004). Thompson et al (2009) argue that the climatological conditions driving the disappearance of Kilimanjaro's glaciers are unique within the Holocene epoch.

What are the implications of an ice-free East Africa?

A warmer world is certainly impacting vulnerable tropical alpine zones in East Africa, and having widespread implications for the 1.5 million people living around Mt Kilimanjaro (UNEP 2012). Elsewhere in the world, increased glacial meltwater from melting glaciers would increase river discharge, followed by a sharp decline as glaciers shrink (UNEP 2007). In Africa, however, the situation is somewhat different (as we touched upon in my last post). Shrinking glaciers appear to have a negligible impact on water resources at the base of the mountain, as ice is primarily lost through sublimation and glaciers are too small to act as water reservoirs (UNEP 2012; Mölg et al 2013). Sublimation means that even when ice is melting, it immediately dries up and evaporates directly into the atmosphere.

The impacts for people in this part of East Africa focus on a loss of tourism - a vital industry providing significant income to Tanzania's economy (UNEP 2012). People may no longer travel to Tanzania, in awe of the beautiful year-round snow-capped mountains, standing tall amongst the arid plains near the equator. There may indeed be a surge of tourism for the next decade or so as people rush to seize a final opportunity to witness tropical glaciers before they become a myth of the past. But once these glaciers have gone, tourism will undoubtedly suffer a grievous aesthetic loss, as will established alpine ecosystems on the mountain. Policies and agendas regarding climate change in East Africa must address ways to adapt to these impacts which promote economic development, without encouraging the main cause of global warming in the first place: fossil fuel combustion (UNEP 2012). Additionally, before all ice is lost from Kilimanjaro, we should try to clarify and extend our understanding of the atmospheric drivers behind glacier decay in vulnerable tropical regions (Kaser et al 2004).