Impact on current Arabica coffee production zones
Most current Arabica coffee producers across the Indonesian islands will be severely affected by climate change, especially in North Sumatra, Aceh and Flores, but also in Sulawesi and Bali. Flores may actually cease to grow Arabica coffee within the coming decades. Through increasing temperatures, the climatically suitable zones for cultivating Arabica coffee will shift upward, and large areas that are currently under coffee will acquire climates that are not currently used for quality coffee production. This is projected to affect 84 % of the current coffee production zones. This does not mean that coffee could not be grown anymore in the areas classified as unsuitable, but that the climate would be sufficiently different from climates currently used for growing Arabica coffee in the country to expect significant impacts on productivity and quality (Table 2). Since coffee quality is sensitive to temperature, the general temperature increase could mean a decrease in quality, while the decrease in rainfall on the southern islands could also result in reduced yields. In very rainy parts of the northern islands, on the other hand, a further increase in rainfall might also negatively affect yields. For example, very low yields of <150 kg ha−1 have been recorded in Sulawesi (Marsh and Neilson 2007; Neilson et al. 2013). These appear to be at least partly due to the absence of a dry period sufficient to trigger abundant flowering and excessive rainfall resulting in poor fruit set. Higher temperatures and rainfall may compel farmers to switch from Arabica to other crops. These may include Robusta coffee (Coffea canephora), a related species better adapted to lowland conditions which is already grown in association with Arabica in some parts of Indonesia, but is considered a bulk product that commands a lower price on international markets. Pest and disease pressures may also change in a warmer and wetter climate (Garrett et al. 2011), notably through an upward expansion of the coffee berry borer (Hypothenemus hampei) (Jaramillo et al. 2009). This suggests that the next generation of existing coffee farmers, at least those not willing to migrate, may gradually have to modify livelihood strategies away from the cultivation of Arabica coffee.
Possible expansion of Arabica coffee production zones
While many current Arabica coffee farmers may have to change crops over coming decades, other farmers may migrate to higher altitudes and establish new coffee farms and potentially new settlements. By 2050, after climate change has taken its toll, the total area with climatically and topographically suitable conditions for growing Arabica coffee (240,000 ha) will be about one-third smaller than the suitable area in the current production zones (360,000 ha; Table 1). However, not all of that currently suitable area is actually used for growing coffee. Based on typical Indonesian yield levels of little over 0.5 t per ha (International Coffee Organization, http://www.ico.org/countries/indonesia.pdf), only approximately 186,000 ha are needed for producing Indonesia’s annual output of 93,000 t of Arabica coffee (average of the last 4 years, http://gain.fas.usda.gov/; see also Table S1). This reflects the fact that in Indonesia, Arabica coffee is mostly grown in small plots within a mosaic of other crops and land uses. Therefore, the estimated area suitable for Arabica coffee in 2050 (240,000 ha) would still be about 30 % larger than the area currently used for growing this crop. This does not include the large suitable areas within protected areas and protection forests, for example, in Aceh (Fig. 1). This suggests that production losses owing to climate change in current production zones could potentially be compensated by new coffee planting in areas that remain or become climatically suitable outside the current production zones. This compensation would especially be possible if the new plantings were managed more intensively than some of the old plantings that may go out of production.
The largest climatically suitable areas for such expansion (or relocation) of coffee farming by 2050 would be in Sulawesi, whose high mountain areas would become more climatically suitable for agriculture through rising temperatures (Fig. 1). Here, about 95,000 ha were classified as climatically suitable in 2050, over twice the suitable area in the current coffee production zone (Table 1). Although much of this area is now relatively inaccessible, it may become increasingly attractive for prospective coffee farmers over the coming decades as long as the predicted increases in rainfall don’t negatively affect yield potentials for these areas. Similar potential of coffee production to shift to areas outside the current production zone was also evident in Aceh (Table 1). In Indonesian Papua, where small amounts of Arabica coffee are currently grown at altitudes between 1,400 and 2,000 m, a substantial expansion potential may also exist based on physical suitability alone. This area was not included in our study, in part because social and political constraints are currently restricting coffee production there.
Winner or loser of climate change?
Our model only identified potentially suitable areas based on climate and topography. Some of these areas at higher altitudes may not be appropriate because of their remoteness, because they have poor soil or are under other land uses, or perhaps because they will be included in future protected areas. Social and economic constraints are also paramount, as coffee farming in Indonesia is highly labor intensive and ultimately depends on a population willing to work in the farms. Therefore, our results should not be seen as a prognosis of future developments in the Indonesian Arabica coffee sector, but rather as an indication of a potential that may or may not be realized, and an input into corresponding discussions and planning processes in the public and private sectors.
Whether coffee production ultimately expands into new climatically suitable areas will depend upon various factors that are almost impossible to predict at this stage, as it is likely that other agricultural commodities, such as vegetable and fruit crops, will face similar supply constraints and may be competing for access to the same land. The ability of lead firms in different commodity-dependent industries to effectively coordinate their supply chains to encourage and maintain production is likely to be a key factor affecting production choices at the farm level. Government decisions regarding support programs will also be influential. Ultimately, crop and livelihood choices will be strongly shaped by prevailing prices and market demand. These depend in part on the fate of other Arabica coffee origins in a changing climate. A number of studies have shown that the climatic suitability of major Arabica coffee origins in Latin America will strongly decline over the next decades (Eakin et al. 2006; Schroth et al. 2009; Rahn et al. 2014). The prospects of African Arabica coffee producer countries under climate change have not been studied to the same extent (Läderach and van Asten 2012), although available information suggests that impacts may be less severe than in Latin America. However, the probable reduction of production volumes and/or quality in Latin America may open a significant niche for other coffee producers such as Indonesia whose physical geography, according to our analysis, would allow current production levels to be maintained and perhaps even increased.
This relatively positive scenario, however, would require significant shifts among coffee production regions within the country. While Aceh may struggle to maintain its current level of production through a local shift in coffee areas, Arabica coffee output from North Sumatra is likely to decrease. Sulawesi, on the other hand, could potentially become a “relative climate change winner” despite the severe effects that climate change will have on current coffee-producing regions. Coffee production practices in Sulawesi are currently notably extensive and characterized by low per-hectare yields (Marsh and Neilson 2007). One can only speculate whether an increase in demand for its coffee as the output from other production regions within and outside Indonesia decreases might trigger intensification and expansion of current farms, and/or attract a wave of migrants, including perhaps climate-displaced coffee farmers from other parts of the country.
Environmental and policy implications
Coffee farming in Indonesia has a history of driving deforestation through forest frontier dynamics, often in combination with migration of farmers (Arifin et al. 2008; Neilson 2008; Gaveau et al. 2009b; Schroth et al. 2011). Sulawesi has emerged as a global hub of production for another tree crop, cocoa (Theobroma cacao), only in the last 30 years on the back of migrant farmers moving into previously underdeveloped lands from more densely populated areas of the country (Ruf et al. 1996). Therefore, an increase in demand for Indonesia’s coffee through production (and quality) decline elsewhere would almost certainly increase pressure on ecologically important mountain ecosystems (Wiramanayake et al. 2002) where many of Indonesia’s protected areas are located (Gaveau et al. 2009a). It is important, then, that the expansion of coffee land be encouraged into areas that will maintain their climatic suitability for coffee farming into the next decades, and that are not currently within protected areas and protection forests. Ideally, new coffee plantings should be encouraged into previously cleared areas where they can contribute positively to landscape restoration, especially if intercropped shaded practices are used as is common in many parts of Indonesia. Incentive models for stabilizing forest frontiers in coffee areas in Indonesia have been piloted (Schroth et al. 2011) and need wider application. This is an important task to be pursued jointly by government and the private sector (Arifin et al. 2008; Neilson 2008).
In consideration of the potential ecological effects of expanding high altitude coffee cultivation in Indonesia, it may be desirable to promote more intensive management practices in Indonesian coffee production (where yields are currently very low by global standards) as a means to limit the area needed for new planting as old coffee areas are becoming climatically unsuitable. Further, we suggest the need to carefully plan infrastructure development and to create new protected areas in those mountain regions that provide multiple ecosystem services, including biodiversity habitat and water provision (Wiramanayake et al. 2002). A changing climate is likely to place unprecedented demands on these ecosystems both to be agriculturally productive and to provision critical environmental services, and the potential for coffee to be cultivated within this contested landscape remains uncertain. Notwithstanding these caveats, this analysis has identified the climatic and topographic potential for the expansion of Arabica coffee within some islands of Indonesia, while other islands may face a medium-term decline of their Arabica coffee industry.