Climate Change and Distribution of Date Palms Figure 8. The climate (EI) for P. dactylifera in current time and projected using CLIMEX under the MIROC-H GCM running the SRES A2 scenario and for 2030, 2050, 2070 and 2100 for the northern and southern Africa and the Middle East. doi:10.1371/journal.pone.0048021.g008 Interestingly, from northern Venezuela to the central regions, the climate was predicted to be highly suitable for date palms by 2100. In southern Africa (Figure 5), the CS model predicted an expansion of the range of P. dactylifera further inland from now to 2100. In North Africa, particularly in central and southern Algeria, Mauritania, Mali, Niger, all of the Sudan excluding the western side, and southern Tunisia were projected to become progressively less suitable (EI = 0 or EI,1–10) by 2070 and totally unsuitable by 2100 (Figure 5). The CS GCM for the Middle East indicated that by 2030, Saudi Arabia, Iraq and western Iran would remain climatically suitable (Figure 5). However, by 2050 a reduction in climate suitability for P. dactylifera was predicted for all three countries; this trend was particularly accentuated in Saudi Arabia and Iraq by 2100 (Figure 5). In Asia, especially in northern India, eastern Pakistan and southern Afghanistan (Figure 5), and in north- western Australia (Figure 6), there was a considerable reduction in climate suitability for date palms between 2050 and 2100. b) Results from MR model. From the MR GCM, it can be seen that in the Americas, much of the south-western coast of Mexico, North America, eastern Brazil, south-eastern Bolivia, northern Venezuela, Cuba, northern Colombia, and Paraguay are projected to become climatically suitable for date palms between 2030 and 2100 (Figure 7). Moreover, the MR GCM predicted that more areas around Florida may become suitable for this species’ growth by 2100 (Figure 7). The MR GCM projected that by 2100, western Argentina would be more climatically suitable than it is currently. The MR GCM predicted that almost all of the southern regions on the African continent may become suitable for P. dactylifera in the future (Figure 8). In contrast, some countries in North Africa such as Algeria, Mali, Niger, Mauritania and Sudan are projected to become progressively less suitable, with date production becoming completely unviable by 2100 (Figure 8). However, this model projected that some countries such as Namibia, Botswana and parts of southern Zambia are likely to become highly suitable, particularly from 2070 onwards (Figure 8). The MR GCM for the Middle East projected that Saudi Arabia, Iraq and western Iran may remain climatically suitable for date palms until 2050 (Figure 8). However, the model projected that by 2070 the climate of Saudi Arabia, Iraq and western Iran would be significantly less suitable and that by 2100, the climate in large parts of Saudi Arabia and Iraq would be unsuitable for date palm cultivation. Moreover, a considerable reduction in suitability of climate for date palms was found from 2050 to 2100 in Asia, particularly in northern India, eastern Pakistan and southern Afghanistan (Figure 8). The results indicated that there were some differences in the projection of date palm distribution between the CSIRO-Mk3.0 and MIROC-H GCMs. These differing results were due to the varying predictions of future climate by the two GCMs. Based on the two models, cold and wet stresses appear to be the major factors restricting date palm distribution. For example, cold PLOS ONE | www.plosone.org 8 October 2012 | Volume 7 | Issue 10 | e48021