The country’s five leading crops by harvested area are rice,
coconuts, maize, vegetables, and bananas. Apart from
maize, area harvested increased for all these crops between
SUMMARY | APRIL 2010
2001 and 2012, but bananas expanded more rapidly than
rice and coconuts. While maize area did not expand during
that period, maize yields increased by a little more than 50
percent. The increase in the productivity of bananas was
even higher, at just under 60 percent; rice productivity rose
by just over 20 percent; and coconut productivity expanded
by just under 9 percent.
Table 6. Change in mean daily maximum temperature in the
warmest month based on four general circulation models, 2000–
2050
Region
1. Luzon
1.1 Luzon
1.2 CAR
2. Visayas
3. Mindanao
3.1 Mindanao
3.2 ARMM
Total
GFDL
HadGEM
IPSL
MIROC
Degrees Celsius (⁰C)
1.96
1.95
1.98
1.77
1.46
1.47
1.43
1.76
2.58
2.53
2.90
2.31
2.30
2.30
2.31
2.44
1.86
1.86
1.84
1.95
2.10
2.10
2.13
1.96
1.43
1.45
1.25
2.16
1.75
1.77
1.57
1.67
DIRECT IMPACTS OF CLIMATE CHANGE ON AGRICULTURE
Source: Constructed by authors based on WorldClim version 1.4
(Hijmans et al. 2005).
Notes: GFDL = General Fluid Dynamics Laboratory; HadGEM = Hadley
Centre Global Environmental Model; IPSL = Institut Pierre-Simon Laplace; MIROC = Model for Interdisciplinary Research on Climate.
To determine the impact of climate change on yields, the
crop models were used in combination with the Decision
Support System for Agrotechnology Transfer (DSSAT), which
is a software package comprising multiple mathematical
models that “grow” the crop in daily time increments. This
enabled yields to be predicted for every five arc-minute gridcell (approximately 9 or 10 kilometers), the results of which
were then averaged across the major regional groupings,
weighted by crop area.
A comparison of rainfall in the wettest and driest three
months, based on the IPCC’s AR5 analysis and RCP 8.5,
shows changes to 2050 from the 1950–2000 baseline period
(Table 7). Rainfall in both the wet and the dry season increases under all four GCMs. Overall, the HadGEM model
suggests the highest wet season rainfall and the lowest increase in dry season rainfall.
The impact on rainfed rice with low fertilizer use in Luzon is
highly negative in many locations, sometimes exceeding 20
percent (Figure 8). While yield changes in the Cagayan Valley
are projected to be minimal and mostly positive, Central Luzon and MIMAROPA1 are likely to experience large, negative
impacts. On the other hand, Mindanao is likely to experience
yield increases under climate change, with some areas having up to 20 percent higher productivity. Visayas is projected
to experience mostly neutral climate impacts on rainfed rice,
with areas of increase being offset by areas of decrease. Results for rainfed rice and rainfed sugarcane generally show
modest negative impacts (Table 8), with Luzon projected to
experience the greatest impact, followed by Visayas, and
then Mindanao.
Table 7. Comparison of changes in national rainfall levels in the
dry and wet seasons based on four general circulation models,
2000–2050
Rainfall
GFDL
HadGEM
IPSL
Millimeters (mm)
MIROC
Change in the wettest three months
142
176
105
102
Change in the driest
three months
27
17
31
36
Source: Constructed by authors based on the Agricultural Model Intercomparison Project (AgMIP), as part of Phase 5 of the Coupled Model Intercomparison (CMIP5), for Representative Concentration Pathway 8.5.
Notes: GFDL = General Fluid Dynamics Laboratory; HadGEM = Hadley
Centre Global Environmental Model; IPSL = Institut Pierre-Simon Laplace; MIROC = Model for Interdisciplinary Research on Climate.
1
MIMAROPA stands for Mindoro Occidental, Mindoro Oriental, Marinduque, Romblon and Palawan. These are five provinces under Region IV-B in
Luzon.
5