Deepak Kumar Rijal, Ph.D. POTENTIAL IMPACTS OF CLIMATE CHANGE ON AGRICULTURE AND AGRICULTURAL BIODIVERSITY Trade Union Debates around Climate Change 2 Sept 2009, Summit Hotel, Lalitpur
Definition of terms
Evidence of climate change
Impact of climate change on agriculture
Climate change and agro-biodiversity
Climate change adaptation
Biological diversity means the variability among living
organisms; species adapted to current environments.
Genetic resources means genetic material of actual or
Land degradation - reduction or loss of the biological or economic productivity of agricultural land.
Climate change - any change in climate over time whether due to natural variability or as a result of human activity (IPCC, 1996).
Cloud cover and solar radiation
Greenhouse gases - gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and re-emit infrared radiation.
- affects climate
- affects plant growth directly
- affects climate
- does not directly affect plant growth but crop and cropping systems contribute to release of atmospheric CH 4
N 2 O concentration has increased from a pre-industrial value of about 270 to 319ppb in 2005 (IPPC, 2007) but growth rate is approx. constant since 1980.
Change of greenhouse gases
Atmospheric CO 2 concentration has increased from a pre-industrial value of about 280 to 379 ppm in 2005 (IPCC, 2007).
CH 4 concentration has increased from a pre-industrial value of about 715 to 1774ppb in 2005 ( IPCC, 2007) .
(Source: UNEP, GEF, STAP)
Change of temperature
Global temperature has increased (0.76 ºC in 150
years) and continues increasing (IPCC, 2007).
temperature increase differed by regions and seasons.
predicted to increase over time which directly impacts on plant growth.
Change of temperature Estimated change in temperature (ºC) for Nepal (Yogacharya and Shreshtha 1997). 2.9 (0.5) 3.2 (1.0) 3.0 (0.7) 2100 1.6 (0.4) 1.8 (0.6) 1.7 (0.4) 2050 1.1 (0.2) 1.3 (0.4) 1.2 (0.3) 2030 JJF DJF Annual average Baseline Temperature change mean (ºC) (standard deviation) Year
Amount of rain fall increased in some regions
and decreased on the other (IPCC, 2007).
Intensity, frequency and distribution of rain fall
Atmospheric water vapour (RH) change which
rate of evaporation,
rate of potential evapotranspiration,
disease and pests infestation.
Change of rain fall
Cloud cover, humidity and solar radiation
Cloud cover - rain fall - solar radiation related which directly impact plant growth.
Crop may benefit from sunny days as seen in irrigated rice.
- producitvity of monsoon and spring season rice.
Monsoon season crops more vulnerable to
- pest and diseases
Impact of change of rain fall on agriculture
Amount, distribution and intensity of rain fall directly
affect plant growth:
Water is most often a yield limiting factor
poorly supports crop growth,
crop damage by rain fall occurs at critical stages,
less recharging of ground water.
Impacts of climate change on land degradation:
increases soil erosivity,
increased intensity and thunderstorms
sediments in single event could be huge,
degraded areas become more susceptible
Impacts of climate change Drier and prolonged summer? Hotter? Wetter? Hotter? Wet area Drier summer? Warmer? Drier? Hotter? Dry area Cold Areas /Warm-temperate Hot areas / Tropics / Sub-tropics
HOW IS CROP PRODUCTION DETERMINED CO 2 Radiation Temperature Plant character -physiology -phenology -artchitecture. Water Nutrients Soils Weeds Pests Diseases Pollutants Defining factors Limiting factors Reducing factors PRODUCTION LEVEL Actual Attainable Potential PRODUCTION SITUATION (Modified from Lovenstein et al., 1995)
The optimum range of air temperature for successful growth of a crop. Source: Hunsigi and Krishna 1998; Balasubramaniyan and Palaniappan, 2001. Medium 25-30 10 35 Soybean Medium 22-28 18 33 Groundnut Low 27-32 12 40 Cotton Medium 23-30 13 38 Orange Low 18-25 10 35 Tomato Medium 17 10 24 Cabbage Low 18-25 - - Sunflower Medium 15-20 10 27 Beans Very high 17 10 23 Peas High 27 16 38 Banana High 22-30 10 45 Sugarcane Very high 12-20 10 30 Potato Medium 15-20 5 35 Wheat Very high 25 10 45 Maize High 22-30 12 48 Rice Effect of humidity Average air temp ( o C) Minimum air temp. ( o C) Maximum air temp. ( o C) Crops
Comparison of C 3 and C 4 species Does this change affect plant growth? 25 º C 10 º C C 4 Species 15 º C 0 º C C 3 Species Optimum temp. for assimilation Minimum temp. for assimilation Crops
C3 plants evolved first, and represent over 90% of the worlds plant species.
C4 plant species evolved millions years later, in response to changing conditions – lower water availability, higher temperatures and lower level of atmospheric CO2.
C3 plant species do best with increased CO2 concentration but C4 plants perform best in increased temperature conditions.
C3 plants lose 97% of the water uptake up through their roots to transpiration. Under temperate conditions they are more efficient than C4 plants. Yields of most crops, in most areas, could fall as a result of climate change.
C4 plants absorb CO2 much faster and more efficiently than C3 plants. C4 plants produce 50% more biomass yield than C3.
C4 plants will not be affected by climate change directly but indirectly through greater competition from C3 weeds .
Yields of some cereal crops decrease with increasing temperatures and increased solar radiation. At lower latitudes where the vast majority of the worlds poor live – production will fall by 20 to 40% (Seccarelli, 2009).
Impact of increased temperature on C 3 and C 4 species Source: Proc. Crop. Soc. Japan 31, 315-322 C 4 C 3
Research evidence - rice case
temperature of -5 ºC to + 5 ºC with an increment of 1 ºC over observed data
rain fall of -16mm to +16mm with a mean increment of 2mm for rainy days
CO 2 180 to 1230 where control considered was 330ppm.
Mean climatic data between 24 and 42 years used as baseline for the simulation of
Effect of temperature on grain yield of rice, India. Sensitivity of rice yield to atmospheric temperature changes between – 6 _C and + 6_C as simulated by the CERES-Rice model (Saseendran et al ., 2000)
Effects of rainfall on grain yield of rice, India. Sensitivity of rice yield to rainfall receipt as simulated by the CERES-Rice model (Saseendran et al ., 2000)
Effect of climate change in rice yield, India. Comparison between average rice yields at different locations under Climate Change Scenario (cc scenario) and baseline climate (control) scenario. Yield simulated under cc scenario is expressed as percentage departure from the control. (Saseendran et al ., 2000) Δ Yield with projected rain fall, CO 2 conc temperature. Δ Yield with projected temperature
Impact of elevated CO 2 on agriculture
A 10 to 50% increase in growth and yield of C3 crops and a 0 to 10% increase for C4 crops with the doubling of CO2 (Warrick et al ., 1986; Saseendran et al ., 2000).
Effects on water use
-C 4 species uses less water (low PET)
-C 3 species requires more water (high PET)
Damage by air pollutants
- Under elevated CO 2 damage to plant growth done by air pollutants like NOx, SO 2 and O 3 could be reduced because of decreased stomata opening time ( Van de Geijn et al ., 1993 )
Weed crop interactions
A study in USA showed that Increase in aerial temperature above 32 0C would enhance weed competitiveness in soybean field (Tungate et al., 2007).
Recent study shows that taro varieties adapt to wide geographic areas and also local rices to different environments (Rijal, 2007).
hot and humid environments
luxurious growth of the crop
development of alternative habitats
spread and infestation expanding to new areas
diversity of races of diseases and pests
Diseases and pests infestation
Do our genetic resources adapt to cope with climate change?
Do we have enough genetic resources to develop varieties adaptable under climate changed conditions?
Does wild species capable enough to adapt
Is our present research, developement and
Scenario 2 - climates change faster
Present genetic reosurces
Genetic resources are dwindling in times when their needs have been increasing than ever to cope with climate change
Increase temperature, greenhouse gases may restructure diversity when
some species adapted better to climate change
natural or intentional selections of certain species
habitats changed for species with localized adaptation
some species adapt to a wide variety of changes
Grain yield differences for cultivars grown under different ecosystems, Kaski.
Knowledge about genetic resources
Drought tolerant rice landraces grew well when re-introduced to new environment from ex situ . Though adaptation and some quality traits wered changed grain yield unaffected (Tin et al., 2001).
Some taro cultivars adapt to varying temperature and environmental conditions (Rijal, 2007).
Some varieties grow widely across ecosystems while others adapted to environments different than where they are currently grown in (Rijal, 2007).
Sury and Saraswati making crosses between wild rice and traditional varieties to develop varieties adaptable to swampy areas of Begnas, Kaski. Wild rice ( O rufipogon ) at 1150m
Crops and cropping systems that release less methane
Local variety releases 30 to 38% more CH 4 (Liang., et al., 1994;Nue et al., 1994) than improved varieties.
Old plant types vs new plant types
Do present day crop varieties release less methane?
Demand for crops and cropping systems that releases less CH 4
Flooded rice fields greatly contribute to atmospheric CH 4
Source: Neue et al ., 1994
Some changes are predictable
Some changes are unpredictable
Diseases and pests
Aggregate interaction effects
Climate change adaptation C3 or C4, improved or local variety based against monitory, nutrition and resource use Cleverly select species and variety to fit farm plots through an informed manner Crop cover, introduce legumes, green manure, inter-cropping, Green marketing, carbon sequestration, Organic agriculture could be good option –nutrition and food security, Recycling, Reuse, Reduce, and Regenerate R4 Optimum use of synthetic and organic fertilizers, Avoid flooding, and promote intermittent flooding Synthetic fertilizers emit methane FYMcompost also release methane – ground water contamination Select right modern or local variety Some traditional varieties release more methane
Climate change adaptation Recognition, crop insurance and pension scheme and priority under government program Attract trained and educated people Train and empower producers Agriculture hardly retains educated and trained human resources - disincentives to do agriculture Promote knowledge and science based agriculture adaptable to local conditions Promotion of local and scientific knowledge based agriculture Decrease subsidies with increased commercial agriculture and vice versa Policy incentives provisioned for both modern and organic agriculture Two-way, urban-rural demand -supply strategy Subsistence and traditional agriculture supports livelihoods
SADP Nepal - Sustainable Agriculture
LEAD Nepal – Research, community empowerment, organic farming,