A bitter cup:
climate change profile of global production of Arabica and Robusta coffee
Christian Bunn*
Source: Climatic Change - An
Interdisciplinary, International Journal Devoted to the Description, Causes and
Implications of Climatic Change
Via SpringerLink
Published online: December 13, 2014
Abstract
Coffee has proven to be highly sensitive to climate change.
Because coffee plantations have a lifespan of about thirty years, the likely
effects of future climates are already a concern. Forward-looking research on
adaptation is therefore in high demand across the entire supply chain. In this
paper we seek to project current and future climate suitability for coffee
production (Coffea arabica and Coffea
canephora) on a global scale. We used machine learning algorithms to
derive functions of climatic suitability from a database of geo-referenced
production locations. Use of several parameter combinations enhances the
robustness of our analysis. The resulting multi-model ensemble suggests that
higher temperatures may reduce yields of C. arabica, while C. canephora could suffer from increasing
variability of intra-seasonal temperatures. Climate change will reduce the
global area suitable for coffee by about 50 % across emission scenarios.
Impacts are highest at low latitudes and low altitudes. Impacts at higher
altitudes and higher latitudes are still negative but less pronounced. The
world’s dominant production regions in Brazil and Vietnam may experience
substantial reductions in area available for coffee. Some regions in East
Africa and Asia may become more suitable, but these are partially in forested areas,
which could pose a challenge to mitigation efforts.
Discussion
The goal of this study was to examine the implications of
climate change for global coffee production. Analysis of changes in suitability
under the RCP 6.0 scenario shows that climate change may reduce production of
Arabica coffee in many areas, especially in Brazil. Robusta may also be less
suitable in important regions in Brazil and Vietnam. Gains elsewhere will do
little to offset these losses, giving global losses in suitability for both
species of about 50 %. Only East Africa and the Asian island states show
substantial gains in suitability for both species.
We developed a methodology that is based on the notion that an
ensemble of models captures more relevant information than a single model can.
By using a mean of models based on several feasible parameter combinations
rather than a single model our analysis is more robust than previous regional
studies. The extrapolation of the models with spatially-explicit climate
information gave global maps of bothC. arabica and C. canephora that indicate suitability scores in
regions of major production. We applied the underlying models to the outputs of
five global climate models for the RCP 2.6, RCP 6.0 and RCP 8.5 emission
scenarios. We averaged across emissions scenarios to produce maps and analyzed
the change in suitability scores.
Both species show important changes in accumulated suitability
scores at lower latitudes, which become less negative, albeit not positive, at
higher latitudes. A southward latitudinal migration was also proposed by Zullo
et al. (2011) in a regional study in
Brazil. However, we did not find such impacts of climate change in other
regions. Moreover, the gains in suitability in southern Brazil may not be
enough to compensate for losses in suitability over large areas elsewhere.
Similarly, losses in suitability are mostly at low altitudes while higher
altitudes gain in suitability. Schroth et al. (2009) and Simonett (1988) identified similar
altitudinal migration for Arabica in Central America and for Robusta in Uganda,
respectively. These local studies confirm our analysis, which shows that
altitudinal migration of coffee production will likely be a global trend. The
magnitude of this effect, however, depends on how climate change will impact
local conditions.
It has previously been hypothesized that Robusta production may
be able to replace in part the losses in Arabica production due to climate
change. The hypothesis rests on the notion that C.
arabica is heat sensitive and would thus suffer in a hotter
world. In contrast, C. canephora can
tolerate higher temperatures and could thus replace heat-stressed Arabica
coffee. This scenario may be viable in some regions, but our analysis
emphasizes that C. canephora needs climates
with little intra-seasonal variability. This limits the Robusta crop to low
latitudes. Also, as climate may not only become hotter, but also more variable,
this may aggravate negative effects on Robusta coffee production. Thus,
globally both species appear to be equally affected by climate change. It is
noteworthy that the Congo basin, the center of origin of C. canephora, may become unsuitable for the species by
2050 in the high emissions scenario. This warrants further investigation as
many see indigenous varieties as the key to adapt coffee to climate change.
We found that Arabica production in Eastern Africa is less
impacted than in other regions. In contrast, Davis et al. (2012) proposed substantial
reduction in the area suitable for indigenous Arabica varieties in Eastern
Africa. Our data are based on the distribution of commercial plantations, which
have adapted to a broader range of climates than those of Arabica’s native
range. This difference suggests that in areas where coffee production remains
feasible production systems will have to be adapted. The necessary fundamental
changes in local production systems would pose substantial challenges to
smallholder farmers.
Moreover, given the long lifespan of coffee plantations the
feasibility of migrating coffee to land that will be more suitable under
climate change needs further study. The areas of East Africa that will become
more suitable for coffee are currently not forested, in contrast to the Asian
areas that will gain suitability, which currently are under forest.
Climate-induced migration may thus result in further emissions from land-use
change. Whether or not newly-suitable areas will be threatened by conversion to
agriculture depends on economic incentives. Our analysis shows that highly
productive areas of coffee in Brazil and Vietnam may become unsuitable for
coffee in the future. World markets may thus create economic opportunities in
East Africa, but may induce additional deforestation in Asia, where coffee is
already a frontier crop. Policy-makers need to be aware that these are
challenges that they will need to confront.
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Funding: This research was
conducted under the CGIAR Research Program on Climate Change, Agriculture and
Food Security (CCAFS). Christian Bunn received a “Klimafolgenforschung”
fellowship through the Stiftung Humboldt Universität.
Open Access: This article is
distributed under the terms of the Creative Commons Attribution License which
permits any use, distribution, and reproduction in any medium, provided the
original author(s) and the source are credited.
Complete
report: https://www.scribd.com/doc/250478557/A-Bitter-Cup-Climate-Change-Profile-of-Global-Production-of-Arabica-and-Robusta-Coffee
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