The end of the beginning...

Climate change manifests itself in a number of ways in the areas I have examined, and the impacts of this on East Africa’s water are multi-faceted and complex. There is a fundamental need to increase hydrological and meteorological measurements, improving available meltwater, groundwater and river discharge data. This is essential if we are to improve understanding of relationships between climate change and water availability in vulnerable parts of East Africa. With increased data, it may be possible to anticipate when large recharge events, that sustain groundwater abstraction, will occur.

Regional and local aspects of climate change mustn't be overlooked, as hydroclimatic changes are non-uniform across the continent. Entire livelihoods can be based on one seasonal flood. If that flood doesn't arrive in a warmer, uncertain future, crops will fail, livestock will starve, and farmers will lose money. Economic development, without promoting fossil fuel consumption, should be a paramount consideration in policies (UNEP 2012).

An explicit message is sent by the rapid loss of some of Africa's key glaciers: our climate is rapidly changing within the time-frame of human lifetimes. With anthropogenic GHG emissions expected to continue rising indefinitely over the next decade, natural Earth Systems will continue being perturbed. The mountains in tropical East Africa have wider importance to surrounding communities, and climate change impacts local people and their religious traditions as well as affecting physical water availability. Before all ice is lost on Kilimanjaro and the Rwenzoris, we must endeavour to improve understanding of atmospheric drivers behind glacier decay, and apply this knowledge to our planet's other vulnerable tropical regions (Kaser et al 2004). The book of Africa's future water supply is still largely unwritten with uncertain conclusions. Could regularly replenished groundwater from an intensified hydrological cycle be a glimmer of hope in what seems like a desolate future? One thing seems fairly certain: in a warming world, not all of Africa's taps will run dry.

The Breadbasket of Tanzania

The focus of this blog post is policy documentation from the International Union for Conservation of Nature (IUCN) Water and Nature Initiative (WANI) case study, looking at the Pangani River Basin (PRB) in North-East Tanzania (Welling et al 2011). The basin covers an area of 56,300 km² (95%) in Tanzania, with 4,880 km² (5%) of this situated within Kenya (Welling et al 2011). In order to improve management of the limited water resources available for the basin's 3.4 million inhabitants and gather technical information, with an overarching aim of strengthening Integrated Water Resources Management (IWRM), the Pangani River Basin Management Project (PRBMP) was set up in 2002.

A map of the Pangani River Basin (Source: Pangani River Basin, Tanzania Report)

Fertile soils and abundant rainfall mean this basin has been referred to as the 'breadbasket of Tanzania' (Welling et al 2011). In 2011, it was estimated by the WANI case study that ~55,000ha of the basin was being intensely irrigated with inefficient furrow irrigation. As well as irrigation, water from the multiple rivers constituting the basin serve several hydroelectric power (HEP) stations, collectively providing 17% of Tanzania's electricity demand (Welling et al 2011). Together, irrigation and HEP use nearly 90% of surface flow in the Pangani (Barchiesi et al 2011).

Problems within the basin

The basin is already defined as water-stressed (<1200m3 water per person, per year), and thus climate change is exacerbating the problem of there not being enough water supply to meet demands (PRBMP 2015; Welling et al 2011). We saw in my last post that Mount Kilimanjaro's glaciers are receding at dramatic rates due to impacts of climate change, and this is impacting flows in the nearby PRB (IUCN 2011). Flows which used to be several hundreds of metres per second have diminished to below 40m3 (Welling et al 2011; IUCN 2011)! The combined effects of 1.8-3.6°C temperature rise in Tanzania, intensified and unpredictable precipitation patterns, and increased evaporation and evapotranspiration are expected to cause a 6-10% decline in annual basin flows (PRBMP 2015). The reduction in river flow has already caused seawater intrusion 20km upstream from the estuary (PRBMP 2015) and thus future additional reduction will put livelihoods, industry and the economy of Tanzania at stake.

A warming world, with urbanisation, population growth, intensified agriculture, and rising energy demands have all led to increased competition and overexploitation of water resources in the basin (Barchiesi et al). This has caused conflicts to emerge between various stakeholders, such as large-scale and small-scale farmers, livestock keepers, coastal communities, and HEP producers downstream (Welling et al 2011; PRBMP). There is not enough physical water available in the basin to meet the allocations made, thus over-allocation of limited supplies is a key issue to be resolved by the PRBMP.

How to manage these issues?

A growing awareness of problems in the PRB has stimulated action, both in the form of governments and stakeholders. The PRBMP have undertaken climate change modelling assessments, groundwater studies, and integrated flow research in order to improve understanding of environmental flows and thus to better inform decision making for allocation of water in the basin. I believe that encouraging community participation and IWRM, getting opinions and perspectives from all stakeholders, will hopefully reduce conflict between users of the basin in a modifying climatic future.

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).