Global projections of future cropland expansion to 2050 and direct impacts on biodiversity and carbon storage.

Amy Molotoks,Elke Stehfest,Nuala Fitton,Terence P Dawson,Jonathan Doelman,Pete Smith,Fabrizio Albanito

doi:10.1111/gcb.14459

Abstract

Cropland expansion threatens biodiversity by driving habitat loss and impacts carbon storage through loss of biomass and soil carbon (C). There is a growing concern land‐use change (LUC) to cropland will result in a loss of ecosystem function and various ecosystem services essential for human health and well‐being. This paper examines projections of future cropland expansion from an integrated assessment model IMAGE 3.0 under a “business as usual” scenario and the direct impact on both biodiversity and C storage. By focusing on biodiversity hotspots and Alliance for Zero Extinction (AZE) sites, loss of habitat as well as potential impacts on endangered and critically endangered species are explored. With regards to C storage, the impact on both soil and vegetation standing C stocks are examined. We show that if projected trends are realized, there are likely to be severe consequences for these resources. Substantial loss of habitat in biodiversity hotspots such as Indo‐Burma, and the Philippians is expected as well as 50% of species in AZE sites losing part of their last remaining habitat. An estimated 13.7% of vegetation standing C stocks and 4.6% of soil C stocks are also projected to be lost in areas affected with Brazil and Mexico being identified as priorities in terms of both biodiversity and C losses from cropland expansion. Changes in policy to regulate projected cropland expansion, and increased measures to protect natural resources, are highly likely to be required to prevent these biodiversity and C losses in the future.

Highlights

One of the greatest challenges of the 21st century is to meet society's growing food needs whilst simultaneously reducing the environmental impact of agriculture (Foley et al, 2011)
Biodiversity hotspots cover over 23million km2 of which an estimated 0.9 million km2, approximately 3.76%, are projected to be converted to cropland by 2050 (Table 1)
50% of all Alliance for Zero Extinction (AZE) species are estimated to be impacted through habitat destruction from this land‐use change (LUC) (Table 2)

Summary

Introduction

One of the greatest challenges of the 21st century is to meet society's growing food needs whilst simultaneously reducing the environmental impact of agriculture (Foley et al, 2011). Of the world's 13.4 billion hectare land surface, only 3 billion is suitable for crop production (Bruinsma, 2003), which is restricted by availability of land resources and local natural conditions (Delzeit et al, 2017). Half of this is already cultivated (Smith et al, 2010), and there is still a large area of land that would be highly suitable for agriculture that is not currently under cultivation (Delzeit et al, 2017), a large fraction of remaining land is currently beneath tropical forests (Smith et al, 2010). It is extremely undesirable to convert these natural ecosystems, the consequences of which would include increased greenhouse emissions, deterioration of soil quality, degradation of land and freshwater through pollution from chemical fertilisers and loss of biodiversity (Foley et al, 2005, 2011; Smith et al, 2013)

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