The Impact of Climate Variability and Change on Crop Production

Transcription

1 The Impact of Climate Variability and Change on Crop Production Zoran Dimov Faculty of Agricultural Sciencies and Food

2 Facing with Unprecedented Conditions Climate Change are recognized as a serious environmental issues. The build up of greenhouse gases in the atmosphere means that we can expect significant changes in the next few decades and probably for the whole 21th century. A decade ago, researchers asked the what if question. Now: how do we respond effectively to prevent damaging impacts and take advantage of new climatic opportunities. This question requires detailed in information regarding expected impacts and effective adaptive measures. Will yields be maintained on the present range of farms? Where will new crops be grown? Will new processing plants be required? Will there be competition for water?

3 What is Climate Change? World Meteorological Organization (WMO): long-term changes in average weather conditions. Global Climate Observing System (GCOS): all changes in the climate system, including the drivers of change, the changes themselves and their effects International Joint Commission (IJC): refers to climate change as longer term changes in these average conditions, whether due to natural variability or as a result of human activity; usually measured by temperature and precipitation. These changes are typically described in terms of years, decades, or even centuries and millennia. Intergovernmental Panel on Climate Change (IPCC): as a statistically significant variation in the average state of the climate, or in the consistency of weather patterns (typically lasting decades or even longer). U.N. Framework on Climate Change (UNFCC): a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.

4 What is Climate Variability? UNFCC: Climate has been in a constant state of change throughout the earth s 4.5 billion-year history, but most of these changes occur on astronomical or geological time scales, and are too slow to be observed on a human scale. Natural climate variation on these scales is sometimes referred to as climate variability, as distinct from human-induced climate change. WMO: climate variability refers only to the year-toyear variations of atmospheric conditions around a mean state

5 Food demand World population Increase in Food demand 6.7 Billions - 14 billion hectares of ice-free land on Earth,10% are used for crop cultivation, (additional 25% of land is used for pasture). - Over 2 billion tons of grains are produced yearly for food and feed; - Resource management is key to achieve current production levels; for instance, although irrigated land is only 17% of total arable land, irrigated crops supply a significant portion of total production (40% in the case of cereals) consuming 2,500 billion m3 water, or 75% of the total fresh water resources consumed annually; - Agriculture is a significant contributor to land degradation and anthropogenic global greenhouse gas emissions, being responsible for 25% of carbon (largely from deforestation), 50% of methane, and 75% of N2O emitted annually by human activities. - The most important challenge in coming decades = the need to feed increasing numbers of people while conserving soil and water resources, without significantly increasing current arable land

6 Climate Change Effects on Plant Growth and Yield Crop suitability and crop production: Increases in crop yields are only expected in Northern Europe, while the largest reductions are expected around the Mediterranean and in the Southwest Balkans and in the South of European Russia. In Southern Europe, large decreases in yield are expected for spring-sown crops (e.g. maize, sunflower and soybeans). Whilst, on autumn-sown crops (e.g. winter and spring wheat) the impact is more geographically variable, yield is expected to strongly decrease in the most Southern areas and increase in the northern or cooler areas (e.g. northern parts of Portugal and Spain). Some crops that currently grow mostly in Southern Europe (e.g. maize, sunflower and soybeans) will become more suitable further north or in higher altitude areas in the south. The projections scenarios show a 30-50% increase in suitable area for grain maize production in Europe by the end of the 21st century, including Ireland, Scotland, Southern Sweden and Finland. By 2050 energy crops show a northward expansion in potential cropping area.

7 Effects of Elevated CO 2 Plant biomass and yield tend to increase significantly as CO 2 concentrations increase above current levels (robust results in experimental settings: controlled environment closed chambers, greenhouses, open and closed field top chambers, free-air carbon dioxide enrichment (FACE) experiments). Elevated CO 2 concentrations stimulate photosynthesis, increased plant productivity and modified water and nutrient cycles (experiments when double the atmospheric CO 2 concentration: increases leaf photosynthesis by 30% 50% in C3 plant species and 10% 25% in C4 species). Crop yield increase is lower than the photosynthetic response (10 20% for C3 crops and 0 10% for C4 crops). Disagreements of some authors.

8 Interactions of Elevated CO 2 with Temperature and Precipitation Climate changes may often limit the direct CO2 effects on crop and pasture plant species. For instance, high temperature during the critical flowering period may lower positive CO 2 effects on yield (reducing grain number, size, and quality). Increased temperatures during the growing period may also reduce CO 2 effects indirectly, by increasing water demand (yield of rain-fed wheat grown at 450 ppm CO 2 was found to increase up to 0.8 C warming, then declined beyond 1.5 C warming; additional irrigation was needed to counterbalance these negative effects). In pastures, elevated CO2 together with increases in temperature, precipitation, and N deposition resulted in increased primary production, with changes in species distribution and composition. Future CO2 levels may favor C3 plants over C4; yet the opposite is expected under associated temperature increases the net effects remain uncertain.

9 Status of field crops in R. Macedonia in 2008 Agriculture is of significant importance to R. of Macedonia, in terms of employment, rural livelihoods, food security, and exports. Cropland and pastures occupies approximately 50% of the surface area of Macedonia

10 wheat barley maize sunflower 4647 poppy oil rape tobacco rice paddy 2586 rye 3923 sorghum soybean 2852 oats alfalfa sainfoin 3000

11 Climate Projections up to 2100 Cukaliev O, Mukaetov D, Andonov S, Ristevski P, Mircevski I II Comunication to UNCCC; Sector: Agriculture (Applied Methods: analyze of temperature and sum of active temperatures (year and growing period), effective rainfalls (year and growing period), evapotranspiration (year and growing period), water deficit based on difference between water demand (evapotranspiration) and available water (effective rainfalls), length of growing period and some agro-climatic indexes (De Martone and Lang), for periods ( and ). The average increase of temperature in the Republic of Macedonia will be between 1.0 C in 2025, 1.9 C in 2050, 2.9 C in 2075, and 3.8 C in The average sum of precipitation is expected to decrease from -3% in 2025, -5% in 2050, -8% in 2075 to -13% in 2100 in comparison with the reference period

12 Most vulnerable zone to climate changes in R. Macedonia Most vulnerable zone: Povardarie region, especially area of conjunction of Crna and Bregalnica River with Vardar (Kavadarci as coresponding meteorological station). Very vulnerable zones are: Southeastern Part of the country (Strumica) Southern Vardar valley (Gevgelija) Skopje-Kumanovo Valley (Skopje) Ovche Pole (Stip) Less vulnerable zones: Pelagonija Valley (Bitola) Polog (Tetovo and Gostivar - no climate scenario) Big Lake Region (Resen)

13 Crop Production sector 1. Vine grape Povardarie Region 2. Tomato South Eastern part of the country (Gevgelija - Strumica) 3. Winter wheat Skopje - Kumanovo and Ovche Pole area 4. Apple in Big lakes region, especially Resen 5. Alfalfa Bitola area,

14 Yield decreasing (in %) as result of climate changes impact for some field crops area crop Skopje Stip w. wheat w. wheat Bitola alfalfa Calculations 1. Potential Evapotranspiration for three vulnerable region using climate changes according 84 climate scenarios, using mean value 2. FAO methodology for calculation of Crop Yield Response to Water Deficit 3. Crop response factor (ky)

15 Expected decreasing of winter wheat production in Republic of Macedonia year Total annual production / t Decreasing of production / t Cost of decreased production/mil , , , ,6

16 Expected decreasing of alfalfa production in Republic of Macedonia year Total annual production / t Decreasing of production / t Cost of decreased production/mil , , , ,5

17 t/ha Production of maize in R. of Macedonia East Europe West Europe Europa Austr. & NZ Africa North America Azia Macedonia Bulgaria Croatia Greece Serbia Turkey World

18 for maize, moderate (0-10%) and severe yield declines (10-25%) are projected for the majority of Macedonia by However, by 2050 almost all of Macedonia is projected to experience severe maize yield declines of up to 25%, with some highly vulnerable areas projecting catastrophic yield declines of greater than 25%. As maize is a summer crop, these declining yield projections can also be used to some extent as a proxy indicator for other rain fed summer crops, like vegetables

19 Adaptation to climatic change To avoid or at least reduce negative effects and exploit possible positive effects, several agronomic adaptation strategies for agriculture have been suggested. The agronomic strategies available include: 1. short-term adjustments and 2. long-term adaptations. Short-term adjustments = relatively little cost to the farmers, Long-term adaptations and changes in farming systems, institutions, land use etc. may carry considerably higher costs. Some of these costs can be reduced, if timely action is taken.

20 Short-term adjustment (Autonomous adaptations ) Short-term adjustments: efforts to optimise production without major system changes. They are autonomous in the sense that no other sectors (e.g. policy, research, etc.) are needed in their development and implementation. Examples of short-term adjustments are: changes in varieties, sowing dates and fertilizer and pesticide use (through for instance better monitoring, diversified crop rotations, or integrated pest management methods changes in crop species (e.g. replacing winter wheat with triticale cultivars grown during winter season), changes in cultivars and sowing dates (e.g. for winter crops, sowing the same cultivar earlier, or choosing cultivars with longer crop cycle; for summer irrigated crops, earlier sowing for preventing yield reductions or reducing water demand), choosing crops and varieties better adapted to the expected length of the growing season and water availability, and more resistant to new conditions of temperature and humidity; There are many plant traits that may be modified to better adapt varieties to increased temperature and reduced water supply. New crops and varieties may be introduced only if improved varieties will be introduced to respond to specific characteristics of the growing seasons (e.g. length of the day)

21 Long-term adaptations The long-term adaptations: refer to major structural changes to overcome adversity caused by climate change. This involves: changes in land allocation and farming systems, breeding of crop varieties, new land management techniques, etc. This involves changes of land use that result from the farmer's response to the differential response of crops to climate change. The changes in land allocation = means substitution of crops with high inter-annual yield variability (e.g. wheat or maize) by crops with lower productivity but more stable yields (e.g. pasture or sorghum). Crop substitution may be useful also for the conservation of soil moisture. breeding of crop varieties (with higher resilience to increased temperatures, lower precipitation and drought), new land management techniques to conserve water or increase irrigation use efficiencies, and more drastic changes in farming systems (including land abandonment). Increasing the supply of water for irrigation may not be a viable option, since the projections show a considerable reduction in total runoff.

22 Mitigation measures in agriculture There a number of possibilities for reducing emissions of methane and nitrous oxide emissions through improving management practices and introducing new technologies. These options can be grouped according to gases and modes of action: Reduction in direct energy use (fuel, electricity, heating) and indirect energy use (e.g. fertilisers). Substitution of fossil energy through biofuel production and anaerobic digestion of manure etc Increased carbon storage in soils through higher inputs (straw incorporation, manure, cover crops, grass in rotation) and reduced soil organic matter turnover (no-till) Reduced nitrous oxide emissions through tighter nitrogen cycling and through technical measures to reduce emissions from manure stores and from manures and fertilisers applied to soil

23 Suggestions for research needs within agronomy proposed at the 9th Congress of the European Society for Agronomy in Warsaw Genotypic differences in response to CO2 and climate changes need to better understood; Improved understanding of secondary effects, e.g. nutrient losses, weeds, pests and diseases, and their interaction with climate and CO2 change, and inclusion of these effects in crop models; Improved understanding (including experiments) of the effects of extreme events (heat waves, droughts, floods, high intensity rainfall) for the entire agroecosystem functioning; Improved models of climate effects on yield quality; Better models of adaptation options and their applicability at farm and regional scales; Better understanding on how climate change should be linked with improvements in technology (e.g. biotechnology, tillage, pesticides); Improved understanding and tools to improve management across sectors (e.g. between the agricultural and the water sector); Development of models for bioenergy crops and their utilisation; Development of water saving technologies and management practices