Reply on RC1

Alexander Raphael Groos

doi:10.5194/essd-2021-268-ac1

Abstract

Tropical mountains and highlands in Africa are under pressure because of anthropogenic climate and land-use change. To determine the impacts of global climate change on the afro-alpine environment and to assess the potential socio-economic consequences, the monitoring of essential climate and environmental variables at high elevation is fundamental. However, long-term climate observations on the continent above 3,000 m are very rare. Here we present a consistent multinannual ground temperature dataset for the BaleMountains in the southern Ethiopian Highlands, which comprise Africa's largest tropical alpine area. 29 ground temperature data loggers have been installed at 16 sites since 2017 to characterise and continuously monitor the mountain climate and ecosystem of the Bale Mountains along an elevation gradient from 3493 to 4377 m. At five sites above ∼ 3900 m, the monitoring will be continued to trace long-term changes. The generated time series provide insights in the spatio temporal ground temperature variations at high elevation, the energy exchange between the ground surface and atmosphere, as well as the impact of vegetation and slope orientation on the thermal dynamics of the ground. To promote the further use of the ground temperature dataset by the wider research community dealing with the climate and geo-ecology of tropical mountains in Eastern Africa, it is made freely available via the open-access repository Zenodo: https://doi.org/10.5281/zenodo.5172002 (Groos et al., 2021b).

Highlights

Tropical mountains and highlands cover only a relatively small area of the terrestrial surface, but they comprise a variety of landscapes, ecosystems, and climates and provide essential ecosystem services (e.g. Buytaert et al, 2011; Peters et al, 2019)
Tropical alpine environments occur in the New Guinea Highlands in Australasia, in the Andes in South America, and in the Ethiopian Highlands and Eastern Arc Mountains in Africa
Because of the high number of thermistors installed in the Bale Mountains, data gaps in the affected ground temperature time series could be interpolated using hourly data from other measuring sites

Summary

Introduction

Tropical mountains and highlands cover only a relatively small area of the terrestrial surface, but they comprise a variety of landscapes, ecosystems, and climates and provide essential ecosystem services (e.g. Buytaert et al, 2011; Peters et al, 2019). The local impacts of ongoing anthropogenic climate and land-use change on individual tropical mountains are difficult to assess, but general developments such as the continuous shrinkage of mountain glaciers, the elevational shift of ecosystem boundaries, as well as the loss of certain habitats and species are evident (e.g. Kaser, 1999; Colwell et al, 2008; Buytaert et al, 2011; Peters et al, 2019; Rahbek et al, 2019; Veettil and Kamp, 2019). Other effects such as the reduction of the organic 10 carbon storage potential below ground, associated with drier and warmer soil conditions, are discussed as well in this context (Buytaert et al, 2011). Meteorological and ground temperature measurements from a few sites above 4000 m exist for the period 1984-1991 (Hillman, 1986; Gottelli and Sillero-Zubiri, 1990; Miehe and Miehe, 1994), but the data have not yet been digitised, revised, and made publicly available. 35 Within the framework of the joint Ethio-European research unit “The Mountain Exile Hypothesis” (Ossendorf et al, 2019), 10

Results

Discussion

Conclusion