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

Lead Research Organisation: University of Portsmouth
Department Name: Geography

Abstract

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.

Planned Impact

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.

Publications


10 25 50
 
Description We have now collected 3 years of data for 23 sites across Kilimanjaro forming a transect across the mountain from SW to NE. We have discovered that moisture moves up the mountain from the lower slopes to the summit during the daytime and this water availability is influenced by vegetation cover. The NE slope is drier overall than the SW slope and the forest provides moisture to the surroundings.
We have analysed the data to obtain detailed patterns (seasonal and diurnal changes) in the moisture availability across the mountain and this shows that there are daytime contrasts in the cloudiness patterns on the two slopes related to vegetation. It also shows that under widespread precipitation events however that the whole mountain becomes wet/cloudy and thus slope aspect or land cover is less influential in such high precipitation events.
Exploitation Route Use of data in other modelling studies (e.g. paleo-glacial extent).
Use of data in terms of satellite validation of high elevation climate change.
Understanding influence of vegetation on summit ice fields may help land-use policy and conservation.
Sectors Agriculture, Food and Drink,Environment
 
Description Some small amount of data has been used to help with paleo-climate modelling work (see other details) Conservation companies looking at trying to halt deforestation on the slopes of Kilimanjaro have been in contact with me saying they have been inspired by my research. Nothing formal has happened in terms of collaboration yet but we are keeping in touch. The work on deforestation was noted by scientists working on a summary of the benefits of planting trees on global climate (presented in Paris summit in Dec 2016) Climate data on Kilimanjaro has been used by trekking companies to advertise routes etc and advise clients who wish to climb on the mountain
First Year Of Impact 2016
Sector Agriculture, Food and Drink,Environment,Leisure Activities, including Sports, Recreation and Tourism
Impact Types Societal
 
Title Kilimanjaro Climate Data 
Description 25 weather stations have been installed up the slopes of Kilimanjaro - with 10 on the NE slope, 10 on the SW slope, 2 on the summit, and 3 at the bottom of the mountain. These data have collected air temperature and relative humidity every hour since 2004, but only the data since September 2012 is part of that funded by the grant. So far data has been collected for September 2012 to September 2015 for most sites, so we have three years of complete data. The data includes air temperature (degC) and relative humidity (%) measured every hour. It has been archived with NERC at CEDA (Centre for Environmental Data Analysis) Pepin, N. (2016): Hourly climate data from 23 stations on Kilimanjaro (East Africa) over three years - Version 1.0. Centre for Environmental Data Analysis, 09 February 2016. doi:10.5285/10ca2f67-1da5-4d4f-854b-dd2895846edb. http://dx.doi.org/10.5285/10ca2f67-1da5-4d4f-854b-dd2895846edb 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact I have offered to provide this data as a project partner on another grant application (Dr Stephanie Mills). This application I believe was unsuccessful but I have still provided the data for paleo-climate modelling of glacial extent on Kilimanjaro. I have also provided this data to modellers in the United States (Dr Udaysankar Nair) for validation of modelling efforts of cloud and precipitation formation on Kilimanjaro. 
URL http://catalogue.ceda.ac.uk/uuid/57116a45a09847a68395c75362436e05
 
Description Paleo-climate modelling of past glacial extent on Kilimanjaro 
Organisation University of Plymouth
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution I have provided some meteorological data from the slopes of Kilimanjaro to aid in paleo-climate modelling of past glacial extent. The partners applied for a research grant from NERC to understand moraine patterns on Kili in more detail, on which I was a project partner.
Collaborator Contribution The partners are undertaking their study to understand past climate of Kilimanjaro and past glacial extent. My data is being used to calibrate their models. I will get joint publications from this possibly in the future.
Impact A grant application to NERC in 2014 by Dr Stephanie Mills of Plymouth (Co-I).
Start Year 2014
 
Description Use of air temperature data to help validate MODIS satellite land-surface temperatures 
Organisation University of Helsinki
Country Finland, Republic of 
Sector Academic/University 
PI Contribution The Department of Geosciences had already spent a lot of time using satellite data to map temperature patterns on Kilimanjaro and the advent of real field data was obviously of interest to them. This lead to a joint study comparing MODIS LST and their previous mapping with my air temperature results.
Collaborator Contribution They provided their satellite maps of Kilimanjaro and the satellite temperature predictions.
Impact One paper submitted to JGR Atmospheres (see publication list)
Start Year 2015
 
Description Open Day presentations on Kili research 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Dr Pepin discussed his research in mountain areas (including Kilimanjaro) to interested potential students at university open days. This has encouraged some students to come to Portsmouth or to become interested in climate science - although it is difficult to get exact numbers because it was part of a much broader program (many other speakers etc).
I have put I am not aware of impact because I don't know (I do think there was but it is not evidenced).
Year(s) Of Engagement Activity 2014,2015
 
Description Workshop on use of satellite data for high elevation climate change monitoring 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This was a spin off workshop associated with the GlobTemp User Consultation Meeting in June 2016 sponsored by the Mountain Research Initiative and the European Space Agency about how to use satellite data to examine climate change at high elevations. This was held at IPMA in Lisbon (which is the main meteorological forecasting agency in Portugal) and was primarily for the satellite community and those practitioners who use such data for environmental programmes. In this way it was not my own academic community so was reaching out beyond the project.
I presented a paper on how the Kilimanjaro data could be used to test and evaluate satellite methods which can be applied worldwide to monitoring climate change in mountain regions.
Year(s) Of Engagement Activity 2016