Northward shift of the agricultural climate zone under 21st-century global climate change

Myron King,Adrian Unc,Lakshman Galagedara,Daniel Altdorff,Joseph Holden,Pengfei Li

doi:10.1038/s41598-018-26321-8

Abstract

As agricultural regions are threatened by climate change, warming of high latitude regions and increasing food demands may lead to northward expansion of global agriculture. While socio-economic demands and edaphic conditions may govern the expansion, climate is a key limiting factor. Extant literature on future crop projections considers established agricultural regions and is mainly temperature based. We employed growing degree days (GDD), as the physiological link between temperature and crop growth, to assess the global northward shift of agricultural climate zones under 21st-century climate change. Using ClimGen scenarios for seven global climate models (GCMs), based on greenhouse gas (GHG) emissions and transient GHGs, we delineated the future extent of GDD areas, feasible for small cereals, and assessed the projected changes in rainfall and potential evapotranspiration. By 2099, roughly 76% (55% to 89%) of the boreal region might reach crop feasible GDD conditions, compared to the current 32%. The leading edge of the feasible GDD will shift northwards up to 1200 km by 2099 while the altitudinal shift remains marginal. However, most of the newly gained areas are associated with highly seasonal and monthly variations in climatic water balances, a critical component of any future land-use and management decisions.

Highlights

A projected consequence of climate change is the decrease of farmland and crop production[1,2,3] in established agricultural regions due to more irregular and extreme weather throughout the cropping season[4,5]
A greater linear northward shift was projected for the western parts of North America, with >850 km in places by 2069, and as much as 932 km (Alberta, Canada) by 2099
We found that the projected GDD5 ≥ 1200 areas in the boreal zone trebled by the end of the 21st-century

Summary

Introduction

A projected consequence of climate change is the decrease of farmland and crop production[1,2,3] in established agricultural regions due to more irregular and extreme weather throughout the cropping season[4,5]. The gain of agronomically feasible areas was projected based on assumptions of temporally stable edaphic conditions[10] and by employing a single climate model, not accounting for kinetic and model-related uncertainties. Understanding of the areas that might reach climatic feasibility for future agronomic use ought to be the first step for any consideration of a northward extension of agriculture. The projection of the future extent of climatically feasible areas requires suitable understanding of plant available heat units and temperature ranges in relation to crop phenology and growth, both commonly integrated and described by growing degree days (GDD) intervals[15,16]. We used the GDD5 ≥ 1200 (°C) threshold to predict future climatic suitability for crops in boreal regions. We offer a baseline for the identification of regions that might warrant in-depth, structured agronomic research, that addresses comprehensively crop, edaphic and economic constraints

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