The role of land-use change on influencing mountain climate on Kilimanjaro, East Africa

Kilimanjaro is changing. There has been extensive deforestation. The summit ice-fields are retreating. The water supply on the lower slopes of the mountain is becoming more unreliable with more flash flooding and more periods of drought. The main cause of the summit ice retreat is that the climate is becoming drier, with less precipitation (hence accumulation of snow), and fewer clouds meaning more sunlight which causes intense sublimation and hence ablation.
The reasons for drying, however, are not well understood. They are believed to be a combination of free air changes due to changes in the Indian ocean upstream to the east, and local-scale land use change (such as deforestation) which may dry out the air locally.
Because the mountain is in the tropics, the sun is strong and it heats the mountain each day. This causes upslope winds that help transport moisture from the rainforests on the lower slopes to the summit region where it is deposited as snow (or at the very least forms cloud that protects the ice fields from sunlight). The upper air itself is normally extremely dry, so it is possible that deforestation could in theory cause ice field decline.
Unfortunately, although we have much high publicity research focusing on the ice-field decline, there is no field data on the slopes of the mountain that measures climate, although high profile and well-funded international campaigns have looked at the mountain summit in isolation. There are also lots of computer models of Kilimanjaro's climate and the effects of deforestation but they have no data against which to validate their simulations.

This research proposes to fill this gap by collecting field observations of temperature and moisture on both the windward dry north-east slope and the lee forested south-west slope, expanding on data already collected by the research team since 2004. The funding will allow collection of two years of data on the south-west slope (10 years in total), and two years on the drier north-eastern slope. As well as the comparison between slopes, we will collect data from subsidiary studies at a more local scale (at given elevations on the south-west slope) examining the contrast between vegetated and deforested/unvegetated locations.

We will be able to compare our results with free-air temperatures and moisture at the same elevations (from reanalysis products which are based on weather balloon records) which will show us how the mountain surface itself is influencing the climate.
We will be able to compare the two slopes to quantify the large scale effect of vegetation (the south-west slope has healthy forest cover but the north-east slope does not) and local scale effects by comparing vegetated/non-vegetated readings on the south-west slope.

We will be able to use the differences we obtain to reconstruct mountain climate back in the past, and also to compare/validate the computer models that are attempting to simulate the effects of land-use change on the mountain.

An understanding of present mountain climate on Kilimanjaro and how vegetation influences temperature and moisture availability and its transport up and downslope is of critical importance to many people in Africa, and indeed around the world. The forests on Kilimanjaro also have a great role in water stabilisation, providing a steady water supply for those who live and farm on the lower slopes below the forest zone and understanding the climatic role of forests will help these people conserve their environment.

Beneficiaries include

1) Those interested in understanding summit ice-field behaviour including glaciologists, cryospheric scientists, and trekking agencies (the tourism industry depends heavily on the presence of summit ice).
2) Those interested in understanding how local land-use change and sustainable practices may effect the hydrological cycle on the mountain - this includes effects on moisture supply on the agricultural lower slopes as well as on the summit ice.

The Kilimanjaro National Park Authorities (KINAPA) have a vested interest in conserving the natural environment and would strongly benefit from a more detailed understanding of the mountain climate for a whole variety of reasons, including plant ecology, tourism safety, animal behaviour etc. Our field data will be of valuable assistance for local ecological studies.
The local economy is based on trekking and tourists who come to see the "mountain snows" - thus the trekking agencies and all those involved in the tourist economy will benefit from a greater understanding of what controls ice behaviour.
Those attempting to conserve the natural forest ecosystems such as TAWIRI (Tanzanian Wildlife Research Institute) will benefit from greater understanding of the role of the forest ecosystem on mountain scale climate, particularly if we can show the extent to which the forests have an overall stabilizing effect on the mountain climate and hydrological cycle. Similarly, the 1 million+ people who live and farm on the fertile lower slopes of the Kilimanjaro region (source: 2003 Tanzanian census report) have a vested interest in forest conservation.

Many organisations including the Tanzanian Academy of Science and the East African Universities Programme (ESAURP) are concerned to promote sustainable development, and research such as this could reinforce the importance of land-use conservation.

A good example of a beneficiary is the local "Roots for Shoots" community-based conservation programme partnership project in north-eastern Tanzania which is attempting to promote sustainable activities on the mountain including development of tree nurseries and fuel efficient stoves; it will also benefit from a greater understanding of the role of surface land-use on mountain climate.

Results from this research could ultimately feed into local policy, including conservation of forest resources, and improvement of living conditions for those reliant on water resources on the lower slopes.