Abstract
Species’ vulnerability to extinction is strongly impacted by their geographical range size. Formulating effective conservation strategies therefore requires a better understanding of how the ranges of the world’s species have changed in the past, and how they will change under alternative future scenarios. Here, we use reconstructions of global land use and biomes since 1700, and 16 possible climatic and socio-economic scenarios until the year 2100, to map the habitat ranges of 16,919 mammal, bird, and amphibian species through time. We estimate that species have lost an average of 18% of their natural habitat range sizes thus far, and may lose up to 23% by 2100. Our data reveal that range losses have been increasing disproportionately in relation to the area of destroyed habitat, driven by a long-term increase of land use in tropical biodiversity hotspots. The outcomes of different future climate and land use trajectories for global habitat ranges vary drastically, providing important quantitative evidence for conservation planners and policy makers of the costs and benefits of alternative pathways for the future of global biodiversity.
Highlights
Species’ vulnerability to extinction is strongly impacted by their geographical range size
Two major drivers of the decline of geographic range sizes—the conversion of natural vegetation to agricultural and urban land, and the transformation of suitable habitat caused by climate change—are considered two of the most important threats to global terrestrial biodiversity[3]
Our analysis reveals that species have lost an average of 18% of their natural range sizes far, a figure that may drop to 13% or increase to 23% by the end of the century, depending on future global climatic and socioeconomic developments
Summary
Whilst the first billion hectares converted since 1700 caused an average 3% loss of habitat size, the most recently converted half billion hectares are responsible for an average loss of 6% of natural range sizes This acceleration of marginal range losses can be explained by a long-term trend in the location of land-use change towards tropical regions, where both local species richness is higher and average ranges sizes are smaller, and where the destruction of natural habitat leads to high relative range losses[36] (Fig. 2b, c). Whilst SSP 1 would enable the re-expansion of ranges in many parts of the world as the result of the abandonment of agricultural areas, notably in Southeast Asia, SSP 3 represents a continuation of land-use change in the tropics, most strongly in the Congo basin (Supplementary Fig. 4). Whilst our data quantify the drastic consequences for species’ ranges if global land use and climate change are left unchecked, they demonstrate the tremendous potential of timely and concerted policy action for halting and partially reversing previous trends in global range contractions
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