impact of climate change on agriculture

Important Environmental Issues Affecting Agriculture

Ø  Population Growth

Ø  Increasing and Wasteful Resource Uses

Ø  Global Climate Change

Ø  Biodiversity:

Ø  Extinction of plant and animals and destruction and degradation of wildlife habitat

Ø  Pollution

Ø  Poverty

Ø  All of the above issues are inter-linked, interrelated and mutually dependant both positively and negatively; locally, regionally and globally.

Ø  Most of them are growing exponentially

Despite technological advances, such as

v  Improved varieties,

v  Genetically modified organisms

v  Irrigation system,

            weather is  still a key factor in agricultural productivity, as well as soil properties and natural communities

Effects of Climate Change

  Agriculture

•         Shift in food growing areas

•         Changes in crop yields

•         Increased irrigation demands

•         Increased pests, crop diseases and weeds in warmer areas

Increased CO₂
Impacts on Plant Disease

v  Increased CO2 may increase plant resistance to diseases through changes in host morphology, physiology, nutrient balance

v  Decreased stomatal density increases resistance to pathogens that infect through stomatas

v  Faster mobilization of assimilates to defense sites

v  Reduced N rates decreases susceptibility to some pathogens

Potential Effects of Rising Temperature on Plant Disease

v  Wheat and oats have been found to be more susceptible to rusts at higher temperatures

Increased CO₂
Impacts on Plant Disease

v  Slower debris decomposition rates may increase inoculum carryover between crops

v  Early blight on tomato

v  White mold sclerotia on cabbage

v  increased CO₂ may cause  increased sporulation  of pathogens

Plant Canopy Effects:  Increased Moisture OR CO₂

v  Faster plant growth and/or ample moisture results in denser canopies, increasing humidity, favoring pathogens

How Do Cows Respond to Heat Stress?

n  Higher body temperatures

n  Increased respiration rates (>70/hour)

n  Less activity

n  Increased water intake

n  Seek shade

n  Look for cool areas in the barn

Functions                   

--Lower dry matter intake                  

-          - Alterations in nutrient use   

-          -  Can drop 10 to > 25%

Water Resources

•         Changes in water supply

•         Decreased water quality

•         Increased drought

•         Increased flooding

Forests

•         Changes in forest composition and locations

•         Disappearance of some forests

•         Increased fires from drying

•         Loss of wildlife habitat and species

Sea level

•         Rising sea levels

•         Flooding of low-lying coastal area

•         Beach erosion

•         Disruption of costal fisheries

•         Contamination of coastal aquifers with salt water

Weather Extremes

•         Prolonged heat waves and drought

•         Increased flooding from more frequent, intense, and

•         heavy rainfall in some areas

Human health

•         Increased deaths from heat and diseases

•         Disruption of food and water supplies

•         Increased respiratory diseases and pollen allergies

•         Increased water pollution from coastal flooding

Human Population

•         Increased deaths

•         More environmental refuges

•         Increased migration

The impacts and implications of climate change are:

Ø  Global, far reaching and largely irreversible

Ø  Increases the risk of exposure to hunger, malnutrition and food insecurity among the poorest and most vulnerable people

Ø  Natural disasters are becoming more frequent and intense, land and water are becoming more scarce and difficult to access, and increases in agriculture are becoming more difficult to achieve

What is climate change?

n  Climate:

n  Climate (from Ancient Greek klima, meaning inclination) is the weather averaged over a long period of time usually for 30 years

n  Climate change:

n  It is a change in the statistical distribution of weather over periods of time that range from decades to millions of years. It may be regional or global.

n  In recent usage, especially in the context of environmental policy, climate change usually refers to changes in modern climate. It may be qualified as anthropogenic climate change, more generally known as "global warming" or "anthropogenic global warming" (AGW).

Causes of Climate Change

v  Plate tectonics

v  Solar output

v  Orbital variations

v  Volcanism

v  Ocean variability

v  Human influences

Factors affecting changes in the earth’s average temperature:

Ø  Will the earth continue to get warmer?

Ø  Solar output affect the earth’s temperatures

Ø  Changes in the earth’s reflectivity  affect atmospheric temperatures

Ø  Global warming affect climate by changing ocean currents

Ø  Changes in average sea level that can affect climate

Ø  Changes in cloud cover affect climate

Ø  Air pollution affect climate

Ø  Effect of Increased CO₂ level on photosynthesis

Ø  Can soil absorb more CO₂

Ø  How rapidly could climate shift

Physical Evidence for Climatic Change

n  Historical and archaeological evidence

n  Glaciers

n  Vegetation

n  Ice cores

n  Dendroclimatology

n  Pollen analysis

n  Insects

Climate change and Human Activities

v  Since the beginning of the industrial revolution around 1750 the following human activities

v  Sharp rise in the use of fossil fuel releasing high amounts of CO₂ and CH₄

v  Deforestation and cleaning and burning of grassland to raise crops increased the release of CO₂ and N₂O

v  Cultivation of rice in paddies and use of inorganic fertilizers which released N₂O

CO₂- Dynamics and Rise in Global Atmospheric Temperature

n  50% of the C photosynthesized by plants is returned to the atmosphere as CO2 through plant respiration

n  50% of the remaining C is assimilated and incorporated in plant parts and deposited on or within the soil

n  Since the beginning of the Industrial Revolution in the late 1800

n  The expansion of agriculture

n  Cleaning of forest

n  Burning of fossil fuels

n  Have led to a dramatic increase in [CO₂] atmosphere from 270 ppm to > 380 ppm. Currently the [CH₄] and [N₂O], the GHG, have also increased

n  The global average temperature rise is > 0.6 ^oC

n  This trend is expected to rise in the coming decades unless strong measures are taken to mitigate it

Mitigating Climate Change

n  What is common to the greatest number gets the least amount of care (Aristotle 384-322 BC)

n  Law of Marginality;

            Marginal soils cultivated with marginal inputs produce marginal yields, support marginal living and create a marginal environment prone to physical, social and economic instability.

n  With the increase in world population, there is no choice but to use cutting-edge science including nanotechnology, biotechnology, information technology, and knowledge management to address issues of soil quality restoration, water purification, soil fertility enhancement, and climate change.

n  Principle:

n  Reduce emission of Green House Gases

n  Increase C Sequestrations

            Potential sequestration of C in Global Agricultural Soils through changes in management practices has been variously estimated between 600 to 900 Mt yr-1 over a period of several decades.

Recommended Practices Includes:

q  Re-forestation

q  Agro-forestry

q  Improved farming practices, no-till farming

q  Planting of cover crops

q  Augmentation of soil nutrients (fertilizers, compost, manure and sludge) and legumes

q  Application of soil amendments (liming to acid soil, Gypsum and S to acid soil)

q  Improved grazing

q  Water Conservation

q  Production of energy crops to replace fossil fuels

q  If adopted and implemented efficiently and consistently on a large scale, these practices can help to mitigate GHG effect, reduce soil erosion, improve soil structure and water quality, enhance biodiversity, boost crop yield and promote food security.

These practices will:

o        Increase carbon sequestration

o        Reduce land clearing

o        Increase the use of bio-fuels

o        Increase N use efficiency = less N₂O

o        Increase manure mgmt = less CH₄

Solutions: Dealing with the threat of climate change

What are our options

n  Four school of thoughts

n  First group:    one is to do nothing

n  2^nd group:       To do more research before acting

n  3^rd group:       the growing group of scientists, economists and business leaders believe that we should act now to reduce the risk from climate change. They call for precautionary measures (preventive measure)

n  4^th group:       Act now as part of a no-regrets strategy

Global Warming

Prevention

•         Cut fossil fuel use (especially coal)

•         Shift from coal to natural gas

•         Transfer energy efficiency and renewable energy technologies to developing countries

•         Improve energy efficiency

•         Shift to renewable energy resources

•         Reduce deforestation

•         Use sustainable agriculture

•         Limit urban sprawl

•         Slow population growth

•         Reduce poverty

Clean up

•         Remove CO₂ from smokestack and vehicle emission

•         Store (sequester) CO₂ by planting trees

•         Sequester CO2 under ground

•         Sequester CO₂ in soil by using no-till cultivation and taking crop land out of production

•         Sequester CO₂ in the deep ocean

•         Repair leaky natural gas pipeline and facilities

•         Use feeds that reduce CH₄ emission by belching cows

Let us Act   before  it is too late