6. CONCLUSIONES Y RECOMENDACIONES GENERALES
7.6 Población y Objetivo
that can reduce the risk of negative climate change impacts on agriculture, and to reduce GHG emissions from the agriculture sector.
2.0
OBJECTIVES
At the end of this unit, you should be able to:
• explain the impact of climate change on agriculture
• discuss the potential effects of climate change on pests, diseases and weeds
• discuss the effects of glacier retreat and disappearance on agriculture
• explain the effects of temperature on growing period
• explain the effects of elevated carbon dioxide on crops.
3.0 MAIN CONTENT
iv) Rural space, through the loss and gains of cultivated lands, land speculation, land renunciation and hydraulic amenities.
v) Adaption, organisms may become more or less competitive, as well as human may develop urgency to develop more competitive organisms such as flood resistant or salt resist and varieties of rice.
Agronomists believed that agricultural production will be mostly affected by the severity and the pace of climate change. If change is gradual, there may be enough time for biota adjustment. Rapid change in climate could harm agriculture in many countries, especially those that are already suffering from rather poor soil and climate conditions because there is less time for optimum natural selection and adaptation.
(Briggs and Smithson, 1985).
3.1.1 Observed Impact of Climate Change on Agriculture
Change in crops phenology provides significant evidence of the response to climate change. Phenology is the study of natural phenomena that reoccur periodically and how these phenomena relate to climate and seasonal changes. Phenology has been observed significantly in agriculture and forestry in large parts of the northern hemisphere.Secondly, droughts have been occurring more frequently because of global warming and they are expected to become more frequent and intense mostly in some parts of Africa, and other parts of the world continents. The impacts are aggravated because of increased water demand, population growth urban expansions, and environmental protection efforts in many areas. Drought results in crop failure and loss of pasture grazing land for livestock.
According to IPCC forth assessment report, on impacts of climate change on food security, there could be large decreases in hunger globally by 2080, compared to the previous one experience in 2006.
Reduction in hunger was driven by projected socio-economic development. In Africa, 70% of the populations rely on rain-fed agriculture for their livelihoods; therefore the tendency of food insecurity may likely be in upward projection.
3.1.2 Potential Effects of Temperature on Growing Period
Duration of crop growth cycles are above all, related to temperature. An increase in temperature will speed up development. For instance, annual crops duration of sowing and harvesting will shorten, especially formaize between one and four weeks. The shortening of such cycle may have an adverse effect on productivity.
3.1.3 Effects of Elevated Carbon Dioxide (CO
2) on Crops
In the process of photosynthesis, carbon dioxide is essential to plant growth. Rising CO2 concentration in the atmosphere can have both positive and negative consequences. Increased carbon dioxide CO2 is expected to have positive physiological effects by increasing the rate of photosynthesis. This is known as carbon fertilization. Currently, the amount of CO2 in the atmosphere is 380 parts per million. In comparison, the amount of oxygen is 210, 000 ppm, this means that, plants may be starved of carbon dioxide as the enzymes that fixes CO2
also fixes oxygen in the process called photorespiration. The effects of an increase in CO2 would be higher on C3 crops (such as wheat) than C4
crops (such as maize) because maize is more susceptible to carbon dioxide shortage.
3.1.4 Effects of Climate Change on Quality of Agricultural Products
The importance of climate change impacts on grain and forage quality emerges from new research. For grains such as rice, the amylose content of the grain which is the major determinant of cooking quality may increase under elevated CO2. Cooked rice grain from plants grown in high CO2 environments would be firmer than that from present plants.
However, iron and zinc concentrations will be lower which are important for human nutrition.
The protein content of grains decreases under the combined increase of temperature and CO2 because increase in CO2 leads to decreased concentrations of micronutrients in crop plants. This may have effect on other parts of the ecosystems as herbivores will need to eat more food to gain the same amount of protein. Higher level of CO2 leads to reduced plant uptake of nitrogen resulting in crops with lower nutritional value.
This would impact primarily on populations in poorer countries less able to compensate by eating more food, more varied diets or possibly taking supplements.
Reduced nitrogen content in fields meant for grazing has also been shown to reduce animal productivity especially in sheep, which depends on microbes in their gut to digest plants which in turn depends on nitrogen intake.