hidayat35/climate-signature-of-Africa

This repository contains the analysis code and the derived data needed to reproduce the figures, tables, and headline numbers of the paper: Recovery restriction, not degradation acceleration, is the dominant climate signature in African land-system change since 1985 Hidayat Ullah et al. (in preparation, 2026) # Antecedent drought and African land-cover transitions, 1985–2022 Analysis code for the paper: > **Antecedent drought is more strongly associated with restricted vegetation recovery than with accelerated degradation across Africa, 1985–2022** > Hidayat Ullah, Wilson Kalisa, Shawkat Ali, Jiahua Zhang The study links 30-m land-cover transitions (GLC_FCS30D, 1985–2022) to antecedent drought across the five IPCC AR5 Africa reference regions, using canonical SPEI and SPI series computed from CHIRPS precipitation and TerraClimate potential evapotranspiration. It tests whether the climate signature acts through degradation acceleration, recovery restriction, or both. The **derived data** (analysis rasters and published-table / figure-source CSVs) are archived on Zenodo at **doi.org, because the rasters exceed GitHub's file-size limits. ## Headline findings | Finding | Value | Reference | |---|---|---| | Continental recovery effect (Cohen's *d*), five estimators | −0.158 to −0.182, every interval excluding zero | §3.2 | | Continental degradation effect | +0.015 to +0.040, no interval excluding zero | §3.2 | | Recovery interval excludes zero | 8 of 8 timescale × window combinations | §3.3 | | Recovery–degradation contrast | significant in all 8 combinations (Welch, permutation, mixed-effects) | §3.3, §3.4 | | Degradation equivalent to zero within \|*d*\| = 0.20 | 13 of 14 estimator × timescale tests | §3.2 | | Sahel Recovery Suppression Index | −0.484 (*p* = 0.048) | §3.2 | | Continental AED contribution to drought severity | 26.0%, scaling from 11.3% (SAF) to 44.4% (SAH) | §3.1 | | Wetting vs drying precipitation pixels, Sahara-Sahel | 5.4 : 1, while SPEI-12 dries over 58.1% of pixels | §3.1 | ## Aggregation rule Continental category means are computed in **two stages**, and this matters for anyone reproducing the numbers: 1. Within each region × pathway cell, interval-level *d* values are collapsed by a **transition-pixel-weighte …