Page 143 - Climate Change and Food Systems

chapter 4: an overview of climate change impact on crop production and its variability in europe, related uncertainties and research challenges
productivity is achieved in the western parts of Europe, including France, the United Kingdom, Ireland, Germany, Denmark and the BE-NE-LUX countries (i.e. Belgium, Netherlands, Luxembourg), with average yields ranging from 7 to 9 tonnes
per hectare over the last decade. On the other hand, average wheat yields remain under 4 tonnes per hectare in southern Europe (e.g. Spain) and eastern Europe (e.g. Poland).
3.2 Future shifts in production possibilities (suitability)
The distribution of agricultural cropping areas is characterized by a high spatiotemporal variability. For example, in the short term, cultivation of a given crop will increase if the cost-price ratio
has been favourable in the previous year. In addition, there are long-term trends, such as increase in the cultivation area of biofuel crops (e.g. maize, rapeseed) in response to increased and continued subsidies (see also Section 3.1). Shifts in the distribution of cropping areas are usually determined by the interaction of biophysical factors – including climate, soils and topography – and socio-economic factors (Britz et al., 2011). Among these factors, CC is expected to have a considerable impact on European agriculture and land use (Olesen and Bindi, 2002; Hermans et al., 2010). Elsgaard et al. (2012) analysed the impact of changes in temperature and precipitation on land suitability for crop cultivation and provided model-based estimates of the distribution of selected cereals, including maize, wheat and
oat, for an area reaching from southern France
to central Finland (45-65o N). According to this study, the cultivation area of maize is expected
to increase in all parts of this area, expanding particularly towards northern Europe, including Denmark, Sweden and Finland. In these Nordic countries, growing conditions for agricultural crops are expected to improve, because of climate warming leading to a longer growing season (see also Trnka et al., 2011; Odgaard et al., 2011; Rötter et al., 2012a; Rötter et al., 2013a). The
same extension towards northern latitudes is also anticipated for wheat, with higher cropping shares in the Nordic and Baltic countries. However, the wheat cultivation area is expected to decline in southern and eastern parts of Europe, including France, Hungary and Romania, because drier and hotter summers in these countries in the future will limit crop growth there (Trnka et al., 2011). Further south, the Mediterranean areas
are at particular risk of drought during spring and summer (see Figure 2), reducing the potential for rainfed production. The area cultivated with oats is expected to decrease in the current production centres in southern Finland and mid-Sweden, although for areas in the Nordic countries with
no oat cultivation currently, the cropping share is projected to increase (Elsgaard et al., 2012).
To our knowledge, a comprehensive study on shifts in production potentials that considers expected future trends of the various influential biophysical and socio-economic factors, their interaction at multiple scales (farm, regional, global) and also the resultant impact on shifts in distribution of cropping areas, has not yet been attempted (Wheeler and von Braun, 2013).
3.3 Projections of relative crop yield change under future climate scenarios
Global and European perspectives
A wide range of local and global impact studies have quantified the effects of changes in climate and CO2 on future crop productivity (e.g. Rosenzweig and Parry, 1994; Wolf and van
Oijen, 2003; Parry et al., 2004; Nelson et al.,
2009, 2010). At a global scale, crop productivity
is expected to decrease in many regions of the world if the CO2 fertilization effect is not taken into account. According to a recent study conducted by Müller and Robertson (2014), which did not take the CO2 effect into account, average global wheat yields could be reduced by up to 20 percent, assuming a high-end RCP (RCP8.5; see Figure 6). Estimated yield losses for maize are even higher,
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