M. Mohsin Iqbal, Muhammad Arif Goheer, Humaira Sultana, Sajida Ali Noor, Muhammad. Mudasser , Kashif ...... Mann RA, W.A. Jehangir and I. Masih. 2004.
Research Report GCISC–RR–16
Climate Change and Agriculture in Pakistan: Adaptation Strategies to Cope with Negative Impacts
M. Mohsin Iqbal, Muhammad Arif Goheer, Humaira Sultana, Sajida Ali Noor, Muhammad Mudasser , Kashif Majeed Salik, Syed Sajidin Hussain, Arshad M. Khan
June 2009
Global Change Impact Studies Centre Islamabad, Pakistan
Research Report GCISC-RR-16
Climate Change and Agriculture in Pakistan: Adaptation Strategies to Cope with Negative Impacts
Muhammad Mohsin Iqbal, Muhammad Arif Goheer, Humaira Sultana, Sajida Ali Noor, Muhammad Mudasser, Kashif Majeed Salik, Syed Sajidin Hussain Arshad Muhammad Khan
June 2009
Global Change Impact Studies Centre (GCISC) National Centre for Physics (NCP) Complex Quaid-i-Azam University Campus P.O. Box 3022, Islamabad, Pakistán
Published by: Global Change Impact studies Centre (GCISC) National Centre for Physics (NCP) Complex Quaid-i-Azam University Campus P.O. Box 3022, Shahdra Road Islamabad-44000 Pakistan
ISBN: 978-969-9395-15-4
@ GCISC Copyright. This Report, or any part of it, may not be used for resale or any other commercial or gainful purpose without prior permission of Global Change Impact Studies Centre, Islamabad, Pakistan. For educational or non-profit use, however, any part of the Report may be reproduced with appropriate acknowledgement.
Published in: June 2009
This Report may be cited as follows: Iqbal, M, M., M.A. Goheer, H. Sultana, S.A. Noor, M. Mudasser, K.M. Salik, S.S. Hussain and A.M. Khan, (2009), Climate Change and Agriculture in Pakistan: Adaptation Strategies to Cope with Negative Impacts, GCISC-RR-16, Global Change Impact Studies Centre (GCISC), Islamabad, Pakistan
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CONTENTS Foreword ………………………………………………………….
i
Preface……………………………………………………………… ii List of Tables ………………………………………………………... iii List of Figures ………………………………………………………. iv 1.
Global Climate Change……………………………………………… 1
2.
Impacts on Agriculture……………………………………………… 2 2.1 2.2
Past/Current impacts………………………………………....2 Future impacts…………………………………………...........3
3.
Vulnerability of agricultural system to climate change………….. ..4
4.
Agriculture in Pakistan …………………………………………....... 5
5.
Climate Change studies in Pakistan………………………………….6
6.
Impacts on crop productivity in Pakistan…………………………... 9
7.
Need for adaptation…………………………………………………....10
8.
Adaptation studies at GCISC…………………………………..….... 10
Wheat………………………………………………………………………… .10 Alterations in sowing windows…………….....................................................10 Improving irrigation water use efficiency………….......................................12 Irrigation scheduling at critical growth stages…….. ………………………14 Impacts of climate change and water resources on wheat production…….15 Rice…………………………………………………………………………….18 Dry sowing vs transplanting ………………………........................................18 Optimization of transplanting dates ………………. ……………………….19 9. 10.
Other adaptation options……………………………………………...20 Conclusions …………………………………………………………....22 References ……………………………………………………………..24
i
FOREWORD Global Change Impact Studies Centre (GCISC) was established in 2002 as a dedicated research centre for climate change and other global change related studies, at the initiative of Dr. Ishfaq Ahmad, NI, HI, SI , the then Special Advisor to Chief Executive of Pakistan. The Centre has since been engaged in research on past and projected climate change in different sub regions of Pakistan, corresponding impacts on the country’s key sectors, in particular Water and Agriculture, and adaptation measures to counter the negative impacts. The work described in this report was carried out at GCISC and was supported in part by APN (Asia Pacific Network for Global Change Research), Kobe, Japan, through its CAPaBLE Programme under a 3-year capacity enhancement cum research Project titled “Enhancement of national capabilities in the application of simulation models for assessment of climate change and its impacts on water resources, and food and agricultural production”, awarded to GCISC in 2003 in collaboration with Pakistan Meteorological Department (PMD). It is hoped that the report will provide useful information to national planners and policymakers as well as to academic and research organizations in the country on issues related to impacts of climate change on Pakistan. The keen interest and support by Dr. Ishfaq Ahmad, Advisor (S & T) to the Planning Commission, and useful technical advice by Dr. Amir Muhammed, Rector, National University for Computer and Emerging Sciences and Member, Scientific Planning Group, APN, throughout the course of this work are gratefully acknowledged.
Dr. Arshad M. Khan Executive Director, GCISC
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PREFACE This Report contains the work done in the Agriculture Section of Global Change Impact Studies Centre (GCISC) on the application of Crop Growth Simulation Models, CERESWheat and CERES-Rice, for studying some possible adaptation strategies and identifying appropriate measures to counter the negative impacts of climate change on agricultural productivity in Pakistan. The crop simulation modelling work in Pakistan got an impetus, for the first time, after organization of an International Workshop by GCISC in Chiang Mai, Thailand, in 2004, under the framework of a 3-year APN CAPaBLE project (No. 2005-CRP01CMY-Khan), coordinated by GCISC. The participating countries of the Project were Pakistan, Bangladesh and Nepal. The Project helped build capacity of scientists from various organizations in these countries in crop simulation modelling. The impacts of climate change on the two major cereal crops of Pakistan, namely wheat and rice, were studied at GCISC using the CERES-Wheat and CERES-Rice models, and their results reported in Research Reports (GCISC-RR-14 and GCISC-RR-15). It was found that the yield of wheat will have negative impacts in the northern sub-mountainous region, southern semi-arid plains and southern arid plains while positive impacts only in the northern mountainous region. The yield of rice will also face negative impact in the semi-arid plains. In the light of these studies, efforts were made at GCISC to identify and analyze some adaptation measures to counter the negative impacts of climate change. This work and its results are described in this report. The adaptation strategies studied and described in this Report include: Alteration in sowing window for wheat; Improving water use efficiency by increasing the number of irrigations with total quantity of irrigation water remaining the same; Irrigation scheduling of wheat at critical water-sensitive growth stages; Different method of sowing of Basmati rice (conventional transplanting vs dry sowing); Optimization of transplanting dates of rice, etc. Some other possible adaptation measures related to crop, soil, water use, farm management, and policy improvement were also identified. Further work on studying other aspects of adaptation using crop simulation models, such as technological interventions involving better fertilizer usage, irrigation efficiency improvement, pest and disease control, weed control, and strategies for other major crops is planned.
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List of Tables
Table 1
Farm size in Pakistan
Table 2
DSSAT-based families of crop simulation models acquired by GCISC
8
DSSAT-based crop simulation models currently in use at GCISC
9
5
Table 3
Table 4
Growing season length as influenced by temperature and sowing dates in high-mountainous and sub-mountainous areas of Pakistan
12
Table 5
Impact of irrigation rescheduling on wheat yield
15
Table 6
Water use efficiency for Transplanting and direct seeding of rice
18
Yields of transplanted and direct-seeded rice under different number of irrigations
19
Effect of planting method on growth phases of anthesis and maturity
19
Simulated grain yields under optimal growing season
20
Table 7
Table 8
Table 9
iii iv
List of Figures
Figure 1
The simulated wheat yield under nine sowing dates as influenced by increase in temperature
12
Figure 2
Impact of change in CO2 concentration, temperature and water availability on wheat yield
Figure 3
Change in wheat area under varying climate and water supply for sustaining baseline wheat production
17
Optimization of planting date of rice under temperature and CO2 change
20
Figure 4
iv v
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Climate Change and Agriculture in Pakistan: Adaptation Strategies to Cope with the Negative Impacts 1. Global Climate Change The climate change is very much happening leading inter alia to global temperature increases. The Fourth Assessment Report of Inter Governmental Panel on Climate Change (IPCC) describes that that ‘Warming of the climate system is unequivocal, as is evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level’. They have further provided data leading to high confidence that warming has been due to the globally averaged net effect of human activities (IPCC, SPM, WG-I, 2007). The warming has been more intense during the past decade; 11 of the last 12 years (1995-2006) rank among the 12 warmest years in the instrumental record of global temperatures (since 1850). The linear warming trend over the last 50 years is nearly twice that for the last 100 years. For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES (IPCC Special Report on Emission Scenarios) emission scenarios. Model experiments showed that even if all radiative forcing agents were held constant at year 2000 level, a further warming trend would occur in the next two decades at a rate of 0.1°C per decade. Global warming is primarily the result of increased Greenhouse Gases (mainly CO2, CH4 and N2O). The small concentrations of these gases within the atmosphere cause warming of atmosphere by insulating the earth from heat loss like a blanket on our bed. Since the start of Industrial Revolution in 1750’s, the influence of human activities on climate has picked up tremendously resulting in an increase in the concentration of Greenhouse gases (GHG) which now far exceed the pre-industrial values (CO2 280 ppm, CH4715 ppb and N2O 270 ppb, determined by ice cores spanning many thousands of years) to 379 ppm, 1774 ppb and 319 ppb respectively in 2005. Continued greenhouse gas emissions at or above the current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed in the 20th century (IPCC, 2007). Carbon dioxide, among GHGs, is the most important anthropogenic gas. The annual carbon dioxide concentration growth rate was larger during the last 10 years (1995-2005 average: 1.9 ppm per year) than it had been since the beginning of continuous direct atmospheric measurements (1960-2005 average: 1.4 ppm per year) although there is year to year variability in growth rates. For agricultural crops, higher carbon dioxide levels in the atmosphere may be beneficial as they increase the growth of crops. This is mainly through their effect on crop’s photosynthetic process, as higher levels of carbon dioxide mean that plants absorb more of it – a process known as carbon dioxide fertilization. The increased photosynthetic activity, however, cannot compensate the negative impacts the higher temperatures are exerting on various ecosystems.
2. Impacts on Agriculture In developing countries, nearly 70% of people live in rural areas where agriculture is the largest supporter of livelihood. Growth in agricultural incomes in developing countries prompts the demand for non-basic goods and services fundamental to human development. According to FAO (2004), livelihoods of roughly 450 million of the world’s poorest people are entirely dependent on managed ecosystems including agriculture. These systems are highly sensitive/vulnerable to climate change. Some of the key impacts identified by IPCC are listed below. 2.1 Past/Current Impacts 1. Modelling studies suggest crop yield losses with minimal warming in the tropics. Temperate crops benefit from a small amount of warming (~+2°C) but decline after that. 2. Carbon dioxide fertilization effects increase with warmth but fall once optimal photosynthetic temperatures are exceeded. The CO2 effect may be relatively greater, compared to irrigated crops, for crops under moisture stress. 3. Recent results from Free Air Carbon Enrichment (FACE) studies of CO2 fertilization confirm conclusions from TAR that crop yields at 550 ppm CO2 concentration increase by an average of 17% (Long et al. 2004). Crop model estimates of CO2 fertilization are in the range of FACE results (Tubiello et al. 2006). 4. Crop modelling studies that include extremes in addition to changes in mean climate show lower yields than for changes in means alone (Porter and Semenov, 2005). 5. Rainfed wheat grown at 450 ppm CO2 showed that yield increases upto 0.8°C warming and then declines beyond 1.5°C warming; additional irrigation was needed to counterbalance the negative effects (Xiao et al. 2005). 6. Potential negative yield impacts are particularly pronounced in several regions where food security is already challenged and where the underlying natural resource base is already poor. 7. Climate changes increase irrigation demand in majority of world regions due to combination of increased evaporation from soil surface and increased transpiration from plant leaf surface arising from increased temperatures. This combines with decreased precipitation in some regions and poses a significant challenge to future food security. 8. There is very high confidence that recent warming is strongly affecting terrestrial biological systems, including such changes as:
earlier timing of spring events, such as leaf unfolding, bird migration and egg laying poleward and upward shifts in ranges in plant and animal species High temperatures during flowering may lower CO2 fertilizing effect by reducing grain number, size and quality (Caldwell et al. 2005; Baker et al. 2004; Thomas et al. 2003)
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9. The role of pests has become clearer. The poleward spread of diseases and pests which were previously found at lower latitudes is observed and predicted to continue. The magnitude of the overall effect is unknown but is likely to be highly regionalized. 10. Countries with greater wealth and natural resource endowments adapt more efficiently than those with less. 2.2 Future Impacts 1. Substantial decreases in cereal production potential in Asia could be likely by the end of this century as a consequence of climate change. However, regional differences in the response of wheat, maize and rice yields to projected climate change are likely to be significant (Parry et al. 1999, Rozenweig et al. 2001). 2. Crop simulation modelling studies based on future climate scenarios indicate that substantial losses are likely in rainfed wheat in South and Southeast Asia (Fischer at al. 2002). In South Asia, the drop in yields in non-irrigated wheat and rice will be significant for a temperature increase greater than 2.5°C, incurring a loss in farm level net revenue between 0 and 25% (Kumar and Parekh, 1998). The net cereal production in South Asian countries is projected to decline at least between 4 to 10% by the end of this century under the most conservative climate change scenarios (Lal, 2005). 3. Crop productivity is projected to increase slightly at mid to high latitudes for local mean temperature increases of upto 1-3°C depending on the crop, and then decrease beyond that in some regions 4. At lower latitudes, especially seasonally dry tropical regions, crop productivity is projected to decrease for even small local temperature increases (1-2°C), which would increase risk of hunger. 5. Globally, the potential for food production is projected to increase with increases in local average temperature over a range of 1-3°C, but above this it is projected to decrease. 6. Increase in the frequency of droughts and floods are projected to affect local production negatively, especially in subsistence sectors at low latitudes. 7. Drought affected areas will likely increase in extent. Heavy precipitation events, which are very likely to increase in frequency, will augment food risk. 8. Adaptations such as altered cultivars and planting times allow low- and mid- to high-latitude cereal yields to be maintained at or above baseline yields for modest warming.
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3. Vulnerability of agricultural system to climate change Vulnerability is the degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change, including climate variability and extremes. It is a function of the character, magnitude, and rate of climate variation to which a system, e.g. agriculture, is exposed, and its sensitivity and adaptive capacity. The vulnerability of agriculture system to climate change differs across regions and across populations within regions. Regional differences in baseline climate and expected climate change give rise to different exposures to climate stimuli. The vulnerability can be exacerbated by the presence of other stresses. Non-climate stresses can increase vulnerability to climate change by reducing resilience and can also reduce adaptive capacity because of resource allocation to competing needs. Vulnerable regions face multiple stresses that affect their exposure and sensitivity as well as their capacity to adapt. These stresses arise from, for example, current climate hazard, poverty and unequal access to resources, food insecurity, trends in economic globalization, conflict and incidence of diseases such as HIV/AIDS, Malaria, etc. The productivity of agricultural system is driven by a number of physical, chemical and biological processes and is affected by inter-annual, monthly and daily distribution of climate variables, e.g. temperature, radiation, precipitation, water vapour pressure in the air and wind speed. In some areas, such as hyper arid areas, water resources are already stressed and are highly vulnerable, with intense competition for water supply. Total seasonal precipitation as well as its pattern of variability (Olesen and Bindi, 2002) are both of major importance for agricultural system. Prevailing temperatures determine crop performance when moisture conditions are met. Similarly, when temperature requirements are met, the growth of a crop is dependent on how well its growth cycle fits within the period when water is available. Current vulnerability to climate variability thus depends not only on exposure and sensitivity to these climatic conditions, but on resources and institutions and on the capacity to cope with or adapt to changing conditions including extreme events. It is both hazard- and context-dependent (Brooks, et al 2005). The impacts, adaptive capacity and vulnerability may vary from region to region and even within regions. These differences give rise to key concerns for each region.
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4. Agriculture in Pakistan In Pakistan, agriculture is the mainstay of national economy. It contributes 24% to Gross Domestic Product (GDP), accounts for 60-70% of country’s exports, provides livelihood to 68% of the country’s population living in rural areas and employs 42% of the national labor force. The foremost challenge to agriculture sector is provision of livelihood and other basic needs of the growing population without irreversibly damaging the fragile ecosystem. Being open to vagaries of nature, this sector is highly vulnerable to climate change phenomena. The climate change and variability will impact food and agriculture due to the effects on plant growth and yield of elevated CO2, higher temperatures, altered precipitation and transpiration regimes, increased climate variability, as well as modified weed, pest and pathogen pressure. The key climate-related vulnerabilities in respect of agriculture sector in Pakistan include: • Heat stress on crops due to increasing temperatures • Water shortages – due to increased evapotranspiration and low rainfall in dry areas • Erratic and uncertain rainfall pattern • Increased frequency and intensity of extreme climate events of floods, drought and cyclones • Lack of general awareness about climate change repercussions • Lack of adaptive capacity to adverse climate impacts due to lack of technical know how and low financial resources The communities/regions most vulnerable to climate change in Pakistan are: • Small land holders: 99% of the farmers in Pakistan have land area of 10 hectares (ha) or less, corresponding to 79% of the farmed area (Table 1). Table1. Farm size in Pakistan Farm Size (ha)
% of Farms
Farmed Area (%)
20
1
21
(Source: GoP, 2007). Farmers in the arid and hyper arid regions: Out of total cultivated area of Pakistan of 22.51 million ha (mha), 2.5 mha (10%) are semi-arid, 10.7 mha are arid (48%) and 7.3 mha (32%) are hyper-arid, based on the Aridity Index of Pakistan Agricultural Research Council (PARC). Province-wise, the dry areas constitute 23% of the cultivated area of Punjab, 54% of Sindh, and 60% of both NWFP (North West Frontier Province) and Baluchistan.
5
•
• • •
Farmers of degraded lands: About 17% of land in Pakistan is prone to water erosion, 7.6% to wind erosion, 5.1% to water-logging, and 8.6% to salinity and sodicity. Also, more than 95% of soils are poor in organic matter having less than 1% organic matter content, hence need some sort of external nutrition in the form of commercial fertilizers or organic manures. Farmers of mountainous regions: The mountain ecosystems are very fragile as slight changes in weather parameters can have far reaching effects on their agriculture, livelihood and food security. Farmers of coastal area: The coastal areas are at risk of rising sea level in the wake of global warming as well as of incursion of sea water. The mangrove reserves in the coastal areas of Karachi are already reported to have declined. Farmers of deltaic region: In view of inadequate quantities of river water to repulse the tidal waves in certain years, there can be instances of sea water intrusion into deltaic region with the consequences of increased salinization of soil, shortage of fresh drinking water, crop failures or serious losses in crop yields.
5. Climate change studies in Pakistan Given that Pakistan has a varied type of climate ranging from sub-zero temperatures in the north to above 50°C in the south, a diversity of ecosystems, and a large farming sector with a high level of dependence on irrigation, the impact of changing climate on its society can be wide ranging. The climate change particularly an increase in temperature with a decrease in precipitation would have negative impacts on the production of major agricultural commodities. Some of the earlier studies related to climate change undertaken by Ministry of Environment in collaboration with other national and international organizations are listed below. i)
The Pakistan National Conservation Strategy (1992): The report, prepared by the Government of Pakistan (Environment and Urban Affairs Division) in collaboration with IUCN-The World Conservation Union and funded by CIDA (Canadian International Development Agency), provides national perceptions for planning the development of different sectors of national economy within the context of a National Environmental Plan. Regarding climate change, the report stated, that implications for Pakistan could be potentially large, affecting patterns of agriculture, fisheries and forestry, and that like other countries, Pakistan needs to consider possible effects of global climate change on its developmental plans.
ii)
Climate Change in Asia – Regional Study on Global Environmental Issues (1992-1994): The report, supported by funding from Asian Development Bank (ADB) and finalized in 1994, provided an analysis of Pakistan’s vulnerability to climate events and recommended the technical and economic feasibility of options that could be undertaken to adapt to climate change and also limit GHG emissions or enhance their sinks. A national response strategy was also proposed as part of the study (GoP, 2003).
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iii)
Asia Least Cost Abatement Strategy (ALGAS): Funded largely by Asian Development Bank and completed in 1998, ALGAS project involved 12 Asian nations including Pakistan. The report included the formulation of national GHG abatement strategies consistent with national development priorities, and the preparation of a portfolio of GHG abatement projects and national action plans embodying national development objectives (ALGAS, 1998).
iv)
Country Case Study on Climate Change Impacts and Adaptations Assessment (1996-1998): The study was carried out in implementation of the United Nations Framework Convention on Climate Change (UNFCCC) which aims at stabilization of GHG concentrations at a level that would prevent dangerous anthropogenic interferences with the climate system. Pakistan is a party to this convention. Completed in 1998 through the assistance of GEFUNEP, the study helped assess the impacts of climate change on four major sectors of economy, namely agriculture, forestry, water resources and meteorology. In the Agriculture sector, the impact of climate change on spatial boundaries; growing degree days; growth, yield and water use of wheat, rice and maize crops was studied in the four climatic zones of Pakistan representing humid, sub-humid, semi-arid and arid climates. The present climate change studies in the area of impacts and adaptation have benefited from the work undertaken in the project (GoP/UNEP/GEF, 1998).
v)
CICERO report on Developing strategies for climate change (2000): The study mentioned at 5(iii) above was monitored and reviewed continuously by holding three national Workshops in which national and international experts provided by CICERO (Centre for International Climate and Environmental Research, Oslo, Norway) participated. In 2000, CICERO summarized the results of the above study in a Four-Country Report including Antigua & Barbuda, Cameroon, Estonia and Pakistan. The report provided a basic foundation for understanding the potential impacts of climate change and adaptation measures necessary to address them (CICERO, 2003).
vi)
First National Communication on Climate Change (2003): Having been an active member of ‘Global Commons’, Pakistan signed the UNFCCC in 1992 and ratified the treaty on June 1, 1994. Fulfilling its national obligation as a signatory to UNFCCC, the Government of Pakistan prepared the First National Communication on Climate Change in 2003. Although Pakistan contributes very little to overall global GHG emissions, the report presents a national GHG inventory and identifies sources and sinks of direct and indirect GHGs. The GHG inventory preparation builds on the earlier work on inventory undertaken as part of the ALGAS Project. The report attempts to provide detailed analysis of issues confronting Pakistan climate change planners (GoP, 2003). The report was funded by GEF through UNEP.
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vii) Establishment of Global Change Impact Studies Centre (2002-03): The systematic and planned research work related to climate change in Pakistan became possible after the establishment of Global Change Impact Studies Centre (GCISC) in 2002-03. The Centre was established at the initiative of Dr. Ishfaq Ahmad, Special Advisor to Prime Minister of Pakistan. The Centre set out to study the impacts of climate change on important sectors of national economy such as Water resources, Agriculture, Food security, Energy, Environment, Biodiversity, Health, etc. The efforts were bolstered by approval/award of a 3-year Regional APN CAPaBLE Project in 2003, prepared by GCISC, by Asia Pacific Network for Global Change Research, Japan. Pakistan was the lead country and Nepal and Bangladesh were the two partner countries. The objective of the Project is to build/enhance national capacities of the participating countries in the application of Simulation Models for assessment of climate change and its impacts on water resources, and food and agricultural production. Under this Project, the Agriculture Section of GCISC acquired a Decision Support System for Agro-technology Transfer (DSSAT) incorporating a family of crop models, from Dr. G. Hoogenboom and his group of University of Georgia, Griffin, Georgia, USA (Table 2). Necessary training to selected scientists from the participating countries was provided by Dr. Hoogenboom during a two-week ‘South Asia Training Workshop on Crop Simulation Modelling’ organized by GCISC at Chiang Mai University, Thailand, from June 28-July 9, 2004. For the past three years, the Section has done work using some of these models (Table 3) on assessment of impacts of climate change on productivity of wheat and rice in different agro-ecological zones of Pakistan. Before actual studies on impacts, the CERES-Wheat and CERES-Rice models were calibrated and evaluated under local conditions (Iqbal et al. 2007a and 2007b).
Table 2. DSSAT-based families of crop simulation models acquired by GCISC Models CERES (for Cereals)
Crops Corn, Wheat, Rice, Barley, Sorghum, Millet
CROPGRO (for Grain Legumes Soybean, Peanut, Dry Bean, Chickpea, Cotton and Fiber crops) CROPSIM (for Root Crops)
Potato, Cassava
Oilseed Crops Vegetables Other Crops
Sunflower Bell pepper, Cabbage, Tomato Sugarcane, Pasture
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Table 3. DSSAT based crop simulation models currently in use at GCISC Crop
Crop Model
Use at GCISC
Wheat
CERES-Wheat
In use
Rice Potato Cotton
CERES-Rice SUBSTOR-Potato Cotton-GRO
In use Being tested Being tested
The researchers in Agriculture Section then studied impacts of changing climate on major crops of Pakistan. They studied current effects of increasing temperature and Carbon dioxide levels on growing season length and yields of wheat and rice, using CERESWheat and CERES-Rice models (Iqbal, et al. 2007a and 2007b). They are also studying likely future impacts of rising temperatures, in the wake of global warming, under IPCCSRES A2 and B2 scenarios developed by GCISC for Pakistan from an ensemble of 17 GCMs (Islam, 2007). For wheat, the studies encompassed four agro-climatic zones, viz humid, sub-humid, semi-arid and arid areas of Pakistan, and for rice, semi-arid areas of Pakistan.
6. Impacts on crop productivity in Pakistan The impacts of climatic parameters on wheat and rice productivity in Pakistan have been described in detail in two separate reports prepared by GCISC under APN CAPaBLE project (Iqbal et al., 2007a and 2007b). A list of these impacts has been mentioned here in relation to possible adaptation measures. •
For wheat, the impact of increasing temperature on growing season length was studied in Northern mountainous region (represented by Shangla district, near Gilgit), Northern sub-mountainous region (represented by Islamabad district), Southern semi-arid plains (represented by Faisalabad district) and Southern arid plains (represented by Bahawalpur district) using CERES-Wheat model. The results showed that increase in temperature resulted in reduction in growing season length in all the regions but at a faster rate in the Mountainous region compared to arid and semiarid plains.
•
The impact on yield of wheat, of rise in temperature in the same regions, showed that yield increased in the mountainous region but decreased in the submountainous, arid and semi-arid regions.
•
The increase in CO2 concentration was found to have a positive effect on yield in all the regions, due to CO2 fertilization effect.
•
With the increase of ambient CO2 to 550 ppm as compared to the current level of 380 ppm, the baseline wheat yield in the arid and semi-arid plains could be sustained for temperature increases upto 3°C. In the mountainous areas, the wheat
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yield at 550 ppm CO2 concentration will be higher than the base yield upto 5°C increase in temperature. •
For rice, the impact of increase in temperature on growing season length and yield was studied in Semi-arid plains of Punjab, Pakistan (Sheikhupura district) using CERES-Rice model. The results showed that with rise in temperature by 1 and 5°C over baseline temperature, the growing season length was reduced, from108 days to 102 and 89 days, respectively.
•
Regarding grain yield of rice, the rise in temperature at the ambient CO2 level of 360 ppm resulted in a decreasing trend. Increasing the CO2 level to 550 ppm, on the other hand, increased yield. Due to the combined effect of temperature and CO2 , the baseline rice yield could be sustained for temperature increases upto 1°C provided the ambient CO2 concentration level were to increase from 360 to 550 ppm.
•
7. Need for Adaptation The GCISC studies cited above as well as numerous other studies reported in literature, point to the negative effects of increase in global temperature on crop productivity resulting in possible production shortfalls. The magnitude of increase in temperature may vary from region to region and country to country. The effects may be direct or indirect. The direct effects range from reduction in yield, shortening of growing cycle of plants, sensitivity of reproductive growth stages to heat stress, increased evapotranspiration leading to increased crop water requirements, volatilization losses of surface-applied fertilizer nutrients, surge in insect pests and disease incidence after heavy rain spells, etc. The indirect effects include temporary or permanent excess or shortage of water supplies, and development of biological/physical processes in the soil profile exerting injurious effects on crop health, e.g. water-logging which may lead to salinization of soil, denitrification which may lead to losses of nitrogenous fertilizers, anoxic conditions which may lead to unavailability of certain nutrients, etc. Such negative effects call for some urgent coping mechanisms or adaptation measures to counter them.
8. Adaptation Studies at GCISC Adaptation refers to adjustment in natural or human system in response to actual or expected climate stimuli or their effects, which moderate harm or exploit beneficial opportunities. Various types of adaptations can be distinguished; e.g. anticipatory or reactive, private or public, and autonomous or planned. 8.1
Wheat
8.1.1 Alterations in sowing window In the wake of global warming, the dry arid areas are likely to experience vulnerability of sensitive growth stages of wheat to high temperatures causing drastic 10
reduction in yields whereas the colder mountainous areas are likely to benefit from rising temperatures as low temperature is the key stress in these areas. Aslam et al (2004) stated that analysis of historical climate data offered an opportunity for improvements in the wheat planting window and selection of wheat varieties accordingly. Keeping this in view, the option of change in sowing window was tried to evade the negative effects of high/low temperature on wheat yields in different agro ecological zones of the country and also to assess suitability of sowing date for timely sowing of next crop in the wheat based cropping pattern. st
Nine sowing dates starting from 1 week of October to last week of December at 10-
day interval were tried for wheat sowing in the mountainous and sub-mountainous areas. The simulation results showed that in the high-mountainous area, yields improved with an increase in temperature and a shift towards earlier planting from the current optimum planting date. Freezing temperatures (
