Melting Mountains

Mountain ecosystems are highly vulnerable to climate change, and so they can act as early warning systems for scientists of how other ecosystems are expected to be altered in the future (Kohler and Maselli 2012).

A couple of weeks ago, UNEP released a report on how climate change has impacted mountains in the East African Rift System, including Kilimanjaro. Kilimanjaro is situated in north-east Tanzania, near Kenya, and is the highest mountain in Africa (UNEP et al. 2016).

In the past 100 years Kilimanjaro has lost 80% of the glaciers strewn across its peaks, and they are expected to vanish completely within a few decades. This shrinkage is occurring as a result of rising temperatures and reduced precipitation (Kaser et al. 2004): temperatures at Kilimanjaro have increased by 0.27°C per decade (Buytaert et al. 2011), and rainfall has dropped by 39% between 1911 and 2004 (Hemp 2005).

However, although the melting of glaciers may be catastrophic from a scientific perspective as their ice layers contain priceless climate records spanning thousands of years, they actually contribute insignificant quantities to river flow and so their loss does not threaten future water supply (Taylor et al. 2009). Nevertheless, it is a stark indicator that environmental changes are occurring (Hemp 2005). Even the name ‘Kilimanjaro’ comes from the Swahili ‘Kilima Njaro’ meaning ‘shiny mountain’ in reference to the glaciers at its peak (UNEP et al. 2016), so maybe even a name change will be required once all the ice caps have melted!

But even if glacial melting is not impacting water supplies, another feature of Kilimanjaro’s changing climate does pose a threat: deforestation.

Kilimanjaro houses tropical montane forest ecosystems which amass water by collecting cloud moisture, and these act as a water source for one of Tanzania’s largest rivers, the Pangani River. Over one million people who live in the region depend on this water for irrigation and domestic use (UNEP et al. 2016).

Warmer, drier conditions due to climate change are triggering more forest fires in Kilimanjaro’s forests, and 13,000 hectares of forest have been destroyed since 1976. Several rivers have dried up as a result of the forest degradation, and this has impacted civilisation below. For example, serious water shortages have hit the town of Moshi situated in the mountain foothills, and the Chagga people living on the southern slopes are lacking water for their irrigation practices, particularly in the dry season. This will impact their food security and livelihoods, but the greatest burden will be shouldered by the women and children who will have to travel further distances to collect the water (UNEP et al. 2016). It is estimated that the reduced fog interception has caused annual dew from the forest to drop by 25%, which is equivalent to the annual water demand of the 1 million people living near Kilimanjaro. Even more worryingly, at this current rate of deforestation, it is estimated that the forest will be completely decimated within the next few years (Hemp 2005).

Therefore UNEP has called on the Tanzanian government to prioritise reforestation projects to reverse these effects and protect this vital water catchment. Such human intervention can be a powerful weapon in the fight against the threat of climate change on water supply – so let’s hope this opportunity isn’t wasted.