AMBO University Woliso Campus Department of Agricultural Economics Course out line for the Course Economics of Climate Change
Program: Agricultural Economics
ECTS Credits (CP):
5/3
• Course Title: Economics of Climate Change Course Code: AgEc 462 Name of Instructor: Getahun G.Sem/Year/ Dept: II/AgEc/ IV
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Content Description: Climate Change in Agricultural Economics aims to provide students with a foundational understanding of climate change science, as
well as the opportunity to think critically about its economic consequences and opportunities to apply that expertise in climate change response activities
and market studies. The course covers theoretical understanding of the evolving climate system, as well as the causes of climate change and its
biophysical implications. Implement and evaluate economic analyses of climate change. This study focuses on cost-benefit analyses of climate change
mitigation, the role of adaptation, and alternative approaches to quantifying climate change impacts, particularly in agriculture and agricultural business.
The course encourages critical thinking about economic analysis, including uncertainties about the underlying science and how to value costs and benefits;
and the role of norms and values, especially concerning the health effects of climate change. The course also provides an introduction to the climate
change policies and carbon emission arguments. Putting climate change in the framework of economic analysis, we can consider greenhouse gas
emissions, which cause planetary warming and other changes in weather patterns, as both a cause of environmental externalities and a case of the overuse
of a common property resource.
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Course Objectives: At the end of the course, the student should be able to:
Understand the concepts and theories of climate change
Understand causes and relationships between agriculture and climate change.
Describe climate change effects on major economic activities (Agriculture, industry & service sectors)and impacts and
contributions of these activities to climate change
Explain and critically evaluate alternative approaches to assessing the economic effects of climate change, particularly in
agriculture, and the role for adaptation and mitigation.
Apply knowledge of the science and responses against climate change including climate smart agricultural practices, adoption
and mitigation and effective communication strategies
Apply cost and benefit analysis concepts in valuation of climate change damage in agriculture and cost and benefits climate
change adaptation and mitigation practices
Assess the link between climate change and food and nutrition security in developing countries
Explain the scientific and economic implications of climate change in agriculture and develop ideas for effective policy
responses in the context of your country
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Chapter One: Introduction to climate change
1.1. Concepts of climate change
1.2. Causes of climate change
1.3. Predictable and unpredictable climate change
By: Getahun Gebru W/Mariam
AUWC Dept. of Agricultural Economics
CONCEPTS OF CLIMATE CHANGE
• The global climate system although humans and other living beings experience climate
locally, we need to look at the global Earth system to gain an understanding of what
constitutes climate. This involves understanding how air, land, oceans, snow and ice, and all
living things contribute to and interact with the global climate.
• This complex array of relationships is commonly referred to as the climate system (IPCC,
2007a).
• All the parameters of the Earth’s climate (wind, rain, clouds, temperature, etc.) are the result
of energy transfer and transformations within the atmosphere at the Earth’s surface and in the
oceans. Over time, the Earth’s climate remains largely stable because the energy received is
equal to that lost (the energy budget is balanced). The sunlight hitting earth (solar radiance) is
on average, 1370 watts per square meter (W/m²) (World Meteorological Organization 2012).
• The glass walls in a greenhouse reduce airflow and increase the temperature of the air inside.
Analogously, but through a different physical process, the Earth’s greenhouse effect warms
the surface of the planet. Without the natural greenhouse effect, the average temperature at
Earth’s surface would be below the freezing point of water.
• Thus, Earth’s natural greenhouse effect makes life as we know it possible. The Sun powers
Earth’s climate, radiating energy at very short wavelengths, predominately in the visible or
near-visible (e.g., ultraviolet) part of the spectrum. Roughly one-third of the solar energy that
reaches the top of Earth’s atmosphere is reflected directly back to space. The remaining twothirds is absorbed by the surface and, to a lesser extent, by the atmosphere (IPCC, 2007a).
• https://www.epa.gov/climatechange-science/frequently-asked-questions-about-climate-change
• Below are answers to some frequently asked questions about climate change. For
information about evidence of climate change, the greenhouse effect, and the human
role in climate change, please see EPA Climate Science.
• On this page:
• Terms
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What is the difference between weather and climate?
What is climate change?
What is the difference between global warming and climate change?
What is the difference between climate change and climate variability?
• Today’s Climate Change
• Why has my town experienced record-breaking cold and snowfall if the climate is warming?
• Is there scientific consensus that people are causing today’s climate change?
• Do natural variations in climate contribute to today’s climate change?
• Impacts
• Why be concerned about a degree or two change in the average global temperature?
• How does climate change affect people’s health?
• Who is most at risk from the impacts of climate change?
• Solutions
• How can people reduce the risks of climate change?
• What are the benefits of taking action now?
CONCEPTS OF CLIMATE CHANGE
• To balance the absorbed incoming energy, the Earth must, on average, radiate the same amount
of energy back to space. Because the Earth is much colder than the Sun, it radiates at much
longer wavelengths, primarily in the infrared part of the spectrum.
• Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere,
including clouds, and reradiated back to Earth.
• This is called the greenhouse effect. Part of the energy absorbed at the Earth’s surface is
radiated back (or re-admitted) to the atmosphere and space in the form of heat energy. The
temperature we feel is a measure of this heat energy.
• In the atmosphere, not all radiation emitted by the Earth reaches outer space. Part of it is
reflected back to the Earth’s surface by the atmosphere (the greenhouse effect) leading to a
global average of around 14°C, well above the -19°C which would be felt without the natural
greenhouse effect.
• Because the Earth is ovoid and because of its position in the solar system, more solar energy is
absorbed in the tropics creating temperature differences from the equator to the poles.
• Atmospheric and oceanic circulation contributes to reducing these differences by transporting
heat from the tropics to the mid-latitudes and the Polar Regions.
• These equator-to-pole exchanges are the main driving force of the climate system. The energy
budget of the Earth can be changed, which in turn can affect the Earth’s temperature.
CONCEPTS OF CLIMATE CHANGE
• An increase in the greenhouse effect, feedbacks in the climate system, or other changes can
modify the energy budget of the Earth.
• It is important to note that many people commonly confuse weather and climate or consider
them to be one and the same thing. In a scientific sense, and to understand climate change, it is
important to differentiate between weather and climate. Weather is the status of the atmosphere.
• Weather typically changes on a daily basis. The weather can be observed by measuring
meteorological parameters such as temperature, rainfall, atmospheric pressure, relative
humidity, and wind speed.
• Climate is the average status of the atmosphere. It is typically defined over a standard period
of 30 year. While it is possible to observe the day-to-day changes in weather, it is impossible to
directly observe the climate without further scientific analysis (IPCC, 2007a).
• Observations of a changing climate Instrumental observations one and a half centuries show that
temperatures at the surface have risen globally, with important regional variations.
• For the global average, warming in the last century has occurred in two phases, from the 1910s
to the 1940s (0.35°C), and more strongly from the 1970s to the present (0.55°C). An increasing
rate of warming has taken place over the last 25 years, and 11 of the 12 warmest years on record
have occurred in the past 12 years.
• Above the surface, global observations since the late 1950s show that the troposphere (up to
about 10 km) has warmed at a slightly greater rate than the surface, while the stratosphere
(about 10–30 km) has cooled markedly since 1979 (IPCC, 2007a).
CONCEPTS OF CLIMATE CHANGE
• The recent decade (2001- 2010) has produced some of the warmest years globally on record. In 2011, the
average temperature was warmer than the 30-year average in most regions around the world. Warming
was particularly strong in the northern hemisphere, close to the Arctic Circle (Munich Re 2012).
Confirmation of global warming comes from warming of the oceans, rising sea levels, glaciers
melting, sea ice retreating in the Arctic and diminished snow cover in the Northern Hemisphere.
• Consistent with observed increases in surface temperature, there have been decreases in the length of river and lake ice seasons.
Further, there has been an almost worldwide reduction in glacial mass and extent in the 20th century; melting of the Greenland
Ice Sheet has recently become apparent; snow cover has decreased in many Northern Hemisphere regions; sea ice thickness and
extent have decreased in the Arctic in all seasons, most dramatically in spring and summer; the oceans are warming; and sea
level is rising due to thermal expansion of the oceans and melting of land ice (IPCC, 2007a).
• Natural climatic variability Natural fluctuations of the global climate have always occurred and will
continue to influence the Earth’s climate. These fluctuations, also called natural radiative forcings, arise
due to solar changes and explosive volcanic eruptions. Solar output has increased gradually in the
industrial era, causing a small positive radiative forcing (i.e. relative warming).
• This is in addition to the cyclic changes in solar radiation that follow an 11-year cycle. Solar energy
directly heats the climate system and can also affect the atmospheric abundance of some greenhouse
gases, such as stratospheric ozone.
• Explosive volcanic eruptions can create a short-lived (2 to 3 years) negative forcing (i.e. relative cooling)
through the temporary increases that occur in sulphate aerosol in the stratosphere. The stratosphere is
currently free of volcanic aerosol, since the last major eruption was in 1991 (Mt. Pinatubo).
CONCEPTS OF CLIMATE CHANGE
• The differences in natural radiative forcing estimates between the present day and the start of the
industrial era for solar irradiance changes and volcanoes are both very small compared to the differences
in radiative forcing estimated to have resulted from human activities.
• As a result, in today’s atmosphere, the radiative forcing from human activities is much more important
for current and future climate change than the estimated radiative forcing from changes in natural
processes Climate change is also influenced by various regional patterns of climate variability, some of
which may become exacerbated by climate change.
• For example, El Niño Southern Oscillation (ENSO) is a climatic phenomenon that occurs in the southern
Pacific Ocean episodically. ENSO can be linked to global anomalies in climate. These temperature
anomalies are an overlay to the general warming trend observed globally.
• The World Meteorological Organization summarizes ENSO as follows: “Research conducted over recent
decades has shed considerable light on the important role played by interactions between the atmosphere
and ocean in the tropical belt of the Pacific Ocean in altering global weather and climate patterns.
• During El Niño events, for example, sea temperatures at the surface in the central and eastern tropical
Pacific Ocean become substantially higher than normal. In contrast, during La Niña events, the sea
surface temperatures in these regions become lower than normal.
• These temperature changes are strongly linked to major climate fluctuations around the globe and, once
initiated, such events can last for 12 months or more. The strong El Niño event of 1997-1998 was
followed by a prolonged La Niña phase that extended from mid-1998 to early 2001. El Niño/La Niña
events change the likelihood of particular climate patterns around the globe, but the outcomes of each
event are never exactly the same.
CONCEPTS OF CLIMATE CHANGE
• Furthermore, while there is generally a relationship between the global impacts of an El Niño/La Niña event and its
intensity, there is always potential for an event to generate serious impacts in some regions irrespective of its
intensity.” (Source: World Meteorological Organization 2012: n.p.)
• Anthropogenic greenhouse gas emissions Human activities are responsible for post-industrial age climate change
by causing changes in Earth’s atmosphere in the amounts of greenhouse gases, aerosols (small particles), and
cloudiness.
• The largest known contribution comes from the burning of fossil fuels, which releases carbon dioxide gas to the
atmosphere. Greenhouse gases and aerosols affect climate by altering incoming solar radiation and outgoing
infrared (thermal) radiation that are part of Earth’s energy balance.
• The most significant greenhouse gases and their origins are (IPCC, 2007b).
• Carbon dioxide has increased from fossil fuel use in transportation, building heating and• cooling and the
manufacture of cement and other goods.
• Deforestation releases CO2 and reduces its uptake by plants. Carbon dioxide is also released in natural processes
such as the decay of plant matter. Methane has increased as a result of human activities related to agriculture,
natural gas• distribution and landfills.
• Methane is also released from natural processes that occur, for example, in wetlands. Methane concentrations are
not currently increasing in the atmosphere because growth rates decreased over the last two decades.
• Nitrous oxide is also emitted by human activities such as fertilizer use and fossil fuel• burning. Natural processes in
soils and the oceans also release nitrous oxide.
• Halocarbon gas concentrations have increased primarily due to human activities. Natural• processes are also a
small source. Principal halocarbons include the chlorofluorocarbons (e.g., CFC-11 and CFC-12), which were used
extensively as refrigeration agents and in other industrial processes before their presence in the atmosphere was
found to cause stratospheric ozone depletion. The abundance of chlorofluorocarbon gases is decreasing as a result
of international regulations designed to protect the ozone layer.
CONCEPTS OF CLIMATE CHANGE
• Ozone is a greenhouse gas that is continually produced and destroyed in the atmosphere by chemical reactions. In the
troposphere, human activities have increased ozone through the release of gases such as carbon monoxide, hydrocarbons and
nitrogen oxide, which chemically react to produce ozone.
• As mentioned above, halocarbons released by human activities destroy ozone in the stratosphere and have caused the ozone hole
over Antarctica. Water vapour is the most abundant and important greenhouse gas in the atmosphere.
• • However, human activities have only a small direct influence on the amount of atmospheric water vapour. Indirectly, humans
have the potential to affect water vapour substantially by changing climate. For example, a warmer atmosphere contains more
water vapour.
• Human activities also influence water vapour through CH4 emissions, because CH4 undergoes chemical destruction in the
stratosphere, producing a small amount of water vapour. Aerosols are small particles present in the atmosphere with widely
varying size,• concentration and chemical composition. Some aerosols are emitted directly into the atmosphere while others are
formed from emitted compounds. Aerosols contain both naturally occurring compounds and those emitted as a result of human
activities. Fossil fuel and biomass burning have increased aerosols containing sulphur compounds, organic compounds and
black carbon (soot).
• Human activities such as surface mining and industrial processes have increased dust in the atmosphere. Natural aerosols
include mineral dust released from the surface, sea salt aerosols, biogenic emissions from the land and oceans and sulphate and
dust aerosols produced by volcanic eruptions. Often, global greenhouse gas emissions are expressed as CO2e, which refers to
‘carbon dioxide equivalent’.
• This is a measure for describing how much global warming a given type and amount of greenhouse gas may cause, expressed as
the equivalent amount or concentration of carbon dioxide (CO2). As the IPCC confirmed in 2007, greenhouse gas
concentrations in the atmosphere have increased significantly over the past 250 years when compared with the longtime average
over the past 2,000 years (IPCC, 2007a).
• But where do these greenhouse gas emissions come from? The production of greenhouse gases is distributed quite unevenly in
geographic terms and across sectors. While power generation is the origin of over one quarter of all greenhouse gas emissions,
industry, land-use change and forestry, agriculture and transportation are other sectors that significantly contribute to global
emissions. Urban planning can have an effect on a number of these sectors, and it is often directly responsible for land use
changes, as well as a critical force in making changes to transportation systems and efficient power use (The World Bank, 2010).
CONCEPTS OF CLIMATE CHANGE
• Weather is a specific event or condition that happens over a period of hours or days. For example, a thunderstorm, a snowstorm, and today's temperature
all describe the weather.
• Climate refers to the average weather conditions in a place over many years (usually at least 30 years). For example, the climate in Minneapolis is cold
and snowy in the winter, while Miami's climate is hot and humid. The average climate around the world is called global climate.
• Weather conditions can change from one year to the next. For example, Minneapolis might have a warm winter one year and a much colder winter the
next. This kind of change is normal. But when the average pattern over many years changes, it could be a sign of climate change.
• Here's an easy way to remember the difference between weather and climate: Climate helps you decide what clothes to buy, and weather helps you decide
what clothes to wear each day.
• Climate is what we expect, weather is what we get. – Mark Twain
• Climate refers to the average weather conditions in a certain place over many years. For example, the climate in Minnesota is cold and snowy in the
winter, and the climate in Honolulu, Hawaii, is warm and humid all year long. The climate in one area, like the Midwest or Hawaii, is called a regional
climate. The average climate around the world is called global climate.
• When scientists talk about global climate change, they're talking about the global climate and a pattern of change that's happening over many years. One
of the most important trends that scientists look at is the average temperature of the Earth, which has been increasing for many years. This is called global
warming.
• Rising global temperatures lead to other changes around the world, such as stronger hurricanes, melting glaciers, and the loss of wildlife habitats. That's
because the Earth's air, water, and land are all related to one another and to the climate. This means a change in one place can lead to other changes
somewhere else. For example, when air temperatures rise, the oceans absorb more heat from the atmosphere and become warmer. Warmer oceans, in turn,
can cause stronger storms.
• Weather versus Climate
• Weather is a specific event or condition that happens over a period of hours or days. For example, a thunderstorm, a snowstorm, and today's temperature
all describe the weather. Climate refers to the average weather conditions in a place over many years (usually at least 30 years). For example, the climate
in Minneapolis is cold and snowy in the winter, while Miami's climate is hot and humid. The average climate around the world is called global climate.
Weather conditions can change from one year to the next. For example, Minneapolis might have a warm winter one year and a much colder winter the
next. This kind of change is normal. But when the average pattern over many years changes, it could be a sign of climate change.
• Here's an easy way to remember the difference between weather and climate: Climate helps you decide what clothes to buy, and weather helps you decide
what clothes to wear each day.
CONCEPTS OF CLIMATE CHANGE
CONCEPTS OF CLIMATE CHANGE
• Today's Climate Change
• More than 100 years ago, people around the world started burning large amounts
of coal, oil, and natural gas to power their homes, factories, and vehicles. Today,
most of the world relies on these fossil fuels for their energy needs. Burning fossil
fuels releases carbon dioxide, a heat-trapping gas, into the atmosphere, which is
the main reason why the climate is changing.
• Heat-trapping gases are also called greenhouse gases. They exist naturally in the
atmosphere, where they help keep the Earth warm enough for plants and animals
to live. But people are adding extra greenhouse gases to the atmosphere. These
extra gases are causing the Earth to get warmer, setting off all sorts of other
changes around the world—on land, in the oceans, and in the atmosphere. And
these changes affect people, plants, and animals in many ways.
• Learn more about carbon dioxide and other greenhouse gases and how they are
changing the Earth's climate:
CONCEPTS OF CLIMATE CHANGE: Basics
of Climate Change
• Some of the key concepts related to climate change:..\..\Earth science.pdf
The Greenhouse Effect
Key Greenhouse Gases
Other Greenhouse Gases
Aerosols
Climate Feedbacks
• The earth's climate is changing. Multiple lines of evidence show changes in our weather,
oceans, and ecosystems, such as:
• Changing temperature and precipitation patterns.
• Increases in ocean temperatures, sea level, and acidity.
• Melting of glaciers and sea ice. Changes in the frequency, intensity, and duration
of extreme weather events.
• Shifts in ecosystem characteristics, like the length of the growing season, timing of
flower blooms, and migration of birds.
CONCEPTS OF CLIMATE CHANGE
• These changes are due to a buildup of greenhouse gases in our atmosphere and the
warming of the planet due to the greenhouse effect
• GHGs: The earth's temperature depends on the balance between energy entering and
leaving the planet’s system. When sunlight reaches the earth’s surface, it can either be
reflected back into space or absorbed by the earth. Incoming energy that is absorbed by
the earth warms the planet.
• Once absorbed, the planet releases some of the energy back into the atmosphere as heat
(also called infrared radiation). Solar energy that is reflected back to space does not
warm the earth.
• Certain gases in the atmosphere absorb energy, slowing or preventing the loss of heat to
space. Those gases are known as “greenhouse gases.” They act like a blanket, making
the earth warmer than it would otherwise be.
• This process, commonly known as the “greenhouse effect,” is natural and necessary to
support life.
• However, the recent buildup of greenhouse gases in the atmosphere from human
activities has changed the earth's climate and resulted in dangerous effects to human
health and welfare and to ecosystems.
CONCEPTS OF CLIMATE CHANGE: Key
Greenhouse Gases
• Most of the warming since 1950 has been caused by human emissions of greenhouse
gases.4 Greenhouse gases come from a variety of human activities, including burning fossil
fuels for heat and energy, clearing forests, fertilizing crops, storing waste in landfills, raising
livestock, and producing some kinds of industrial products.
• Carbon Dioxide
• Carbon dioxide is the primary greenhouse gas contributing to recent climate change. Carbon
dioxide enters the atmosphere through burning fossil fuels, solid waste, trees, and other
biological materials, and as a result of certain chemical reactions, such as cement
manufacturing.
• Carbon dioxide is absorbed and emitted naturally as part of the carbon cycle, through plant and
animal respiration, volcanic eruptions, and ocean-atmosphere exchange.
• The carbon cycle is the process by which carbon continually moves from the atmosphere to the
earth and then back to the atmosphere. On the earth, carbon is stored in rocks, sediments, the
ocean, and in living organisms. Carbon is released back into the atmosphere when plants and
animals die, as well as when fires burn, volcanoes erupt, and fossil fuels (such as coal, natural
gas, and oil) are combusted.
• The carbon cycle ensures there is a balanced concentration of carbon in the different reservoirs
on the planet. But a change in the amount of carbon in one reservoir affects all the others.
• Today, people are disturbing the carbon cycle by burning fossil fuels, which release large
amounts of carbon dioxide into the atmosphere, and through land use changes that remove
plants, which absorb carbon from the atmosphere.
Key gas
• Methane
• Both natural and human activities produce methane. For example, natural wetlands, agricultural
activities, and fossil fuel extraction and transport all emit methane.
• Nitrous Oxide
• Nitrous oxide is produced mainly through agricultural activities and natural biological processes. Fossil
fuel burning and industrial processes also create nitrous oxide.
• F-Gases
• Chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, perfluorocarbons, and sulfur
hexafluoride, together called F-gases, are often used in coolants, foaming agents, fire extinguishers,
solvents, pesticides, and aerosol propellants.
• ther Greenhouse Gases
• Ground-Level Ozone
• Ground-level ozone is created by a chemical reaction between emissions of nitrogen oxides and volatile
organic compounds from automobiles, power plants, and other industrial and commercial sources in
the presence of sunlight. In addition to trapping heat, ground-level ozone is a pollutant that can cause
respiratory health problems and damage crops and ecosystems.
• Water Vapor
• Water vapor is another greenhouse gas and plays a key role in climate feedbacks because of its heattrapping ability. Warmer air holds more moisture than cooler air. Therefore, as greenhouse gas
concentrations increase and global temperatures rise, the total amount of water vapor in the
atmosphere also increases, further amplifying the warming effect.
CONCEPTS OF CLIMATE CHANGE
• Aerosols in the atmosphere can affect climate. Aerosols are microscopic (solid or liquid)
particles that are so small that instead of quickly falling to the surface like larger
particles, they remain suspended in the air for days to weeks. Human activities, such as
burning fossil fuels and biomass, contribute to emissions of these substances, although
some aerosols also come from natural sources such as volcanoes and marine plankton.
• Unlike greenhouse gases, the climate effects of aerosols vary depending on what they are
made of and where they are emitted. Depending on their color and other factors, aerosols
can either absorb or reflect sunlight. Aerosols that reflect sunlight, such as particles from
volcanic eruptions or sulfur emissions from burning coal, have a cooling effect. Those
that absorb sunlight, such as black carbon (a part of soot), have a warming effect.
• Not only can black carbon directly absorb incoming and reflected sunlight, but it can
also absorb infrared radiation. Black carbon can also be deposited on snow and ice,
darkening the surface and thereby increasing the snow's absorption of sunlight and
accelerating melt.7 While reductions in all aerosols can lead to more warming, targeted
reductions in black carbon emissions can reduce global warming. Warming and cooling
aerosols can also interact with clouds, changing their ability to form and dissipate, as
well as their reflectivity and precipitation rates. Clouds can contribute both to cooling,
by reflecting sunlight, and warming, by trapping outgoing heat.
Climate Feedbacks
• Climate feedbacks are natural processes that respond to global warming by offsetting or further
increasing change in the climate system. Feedbacks that offset the change in climate are called negative
feedbacks. Feedbacks that amplify changes are called positive feedbacks.
• Water vapor appears to cause the most important positive feedback. As the earth
warms, the rate of evaporation and the amount of water vapor in the air both increase.
Because water vapor is a greenhouse gas, this leads to further warming.
• The melting of Arctic sea ice is another example of a positive climate feedback. As
temperatures rise, sea ice retreats. The loss of ice exposes the underlying sea surface,
which is darker and absorbs more sunlight than ice, increasing the total amount of
warming. Less snow cover during warm winters has a similar effect.
• Clouds can have both warming and cooling effects on climate. They cool the planet by
reflecting sunlight during the day, and they warm the planet by slowing the escape of
heat to space (this is most apparent at night, as cloudy nights are usually warmer than
clear nights).
• Climate change can lead to changes in the coverage, altitude, and reflectivity of clouds.
These changes can then either amplify (positive feedback) or dampen (negative
feedback) the original change. The net effect of these changes is likely an amplifying, or
positive, feedback due mainly to increasing altitude of high clouds in the tropics, which
makes them better able to trap heat, and reductions in coverage of lower-level clouds
in the mid-latitudes, which reduces the amount of sunlight they reflect. The magnitude
of this feedback is uncertain due to the complex nature of cloud/climate interactions
CAUSES….
TO BE CONTINUED….
LECTURE 2
1.2. CAUSES AND CONSEQUENCES OF CLIMATE CHANGE
Intro
• In terms of economic analysis, greenhouse gas emissions, which cause planetary
climate changes, represent both an environmental externality and the overuse of a
common property resource.
• The atmosphere is a global commons into which individuals and firms can release
pollution.
• Global pollution creates a “public bad” born by all -- a negative externality with a wide
impact.
• In many countries environmental protection laws limit the release of local and regional
air pollutants.
• In these situations, in economic terminology, the negative externalities associated with
local and regional pollutants have to some degree been internalized.
• But few controls exist for carbon dioxide (CO2), the major greenhouse gas.
• This global air pollutant has no short-term damaging effects at ground level, but
atmospheric accumulations of carbon dioxide and other greenhouse gases will have
significant effects on global temperature and weather, although there is uncertainty about
the probable scale and timing of these effects.
IS THE GREENHOUSE EFFECT CAUSE?
• If indeed the effects of climate change are likely to be severe, it is in everyone’s interest
to lower their emissions for the common good.
• If no agreement or rules on emissions exist, actions by individual firms, cities or nations
will be inadequate.
Climate change can thus be viewed as a public good issue, requiring collaborative
action.
• Since the problem is global, only a strong international agreement binding nations to act
for the common good can prevent serious environmental consequences
• The sun’s rays travel through a greenhouse’s glass to warm the air inside, but the glass
acts as a barrier to the escape of heat. Thus plants that require warm weather can be
grown in cold climates.
• The global greenhouse effect, through which the earth’s atmosphere acts like the glass in
a greenhouse, was first described by French scientist Jean Baptiste Fourier in 1824.
• Clouds, water vapor, and the natural greenhouse gases carbon dioxide (CO2), methane,
nitrous oxide, and ozone allow inbound solar radiation to pass through, but serve as a
barrier to outgoing infrared heat.
GREENHOUSE EFFECT? …………………
• This creates the natural greenhouse effect, which makes the planet
suitable for life. Without it, the average surface temperature on the
planet would average around -18° C (0ºF), instead of approximately
15°C (60º F).
• The possibility of an enhanced or human-induced greenhouse effect
was introduced one hundred years ago by the Swedish scientist
Svante Arrhenius.
• He hypothesized that the increased burning of coal would lead to an
increased concentration of carbon dioxide in the atmosphere, and
would warm the earth.
• Since Arrhenius’ time greenhouse gas emissions have grown
dramatically.
• Carbon dioxide concentrations in the atmosphere have increased by
about 35% over pre-industrial levels.
INADDITION: CAUSES….
• In addition to increased burning of fossil fuels such as coal, oil and natural gas, synthetic
chemical substances such as chlorofluorocarbons (CFCs) as well as methane and nitrous
oxide emissions from agriculture and industry contribute to the greenhouse effect.
• Scientists have developed complex computer models that estimate the effect of current
and future greenhouse gas emissions on the global climate.
• While considerable uncertainty remains in these models, virtually all scientists agree that
the human-induced greenhouse effect poses a significant threat to the global ecosystem.
• The global average temperature has increased by about 0.7°C (1.3°F) during the 20th
century. The Intergovernmental Panel on Climate Change (IPCC) concluded in 2001 that
humans are already having a discernable impact on the global climate: “most of the
observed warming over the last 50 years is likely to have been due to the increase in
greenhouse gas concentrations.”
• In 2007 they reaffirmed and strengthened this conclusion. Current emissions trends will
lead to a doubling of greenhouse gas concentration over pre-industrial levels by around
2050.
• The IPCC projects a global average temperature increase of 1 to 6 degrees Centigrade, or
2 to 10 degrees Fahrenheit, by 2100. This would have significant impacts on climate
throughout the world.
CAUSES….
CAUSES….
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LECTURE TWO CAUSES….
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BASIC FACTS ON EMISSIONS….
BASIC FACTS ON EMISSIONS Emission per capita: although emissions in the us have decreased; they are still the highest per
capita in the world.
CAUSES OF EMISSIONS: CO2 EMISSIONS BY SOURCE 1. Coal 2. Oil 3. Gas 4. Cement
EMISSION PROJECTIONS FOR 2019: Problem that we are al causing, not just some country.
 Either for the total amount, or for the amount per capita.
• Ex. China is causing a lot of the emission, but they have lots of inhabitants.
• For total emissions, China is very high, but not the highest for percapita emission.
 In fact, quite low per capita emission. (USA, Russia and Japan have more per capita emissions)
GREENHOUSE GAS EMISSIONS BY ECONOMIC SECTORS
1. Electricity and heat production (industry, trnasport, buildings, AFOLU: agriculture, forestry and
other land use) 2. AFOLU (agricolture forestry and other land use) 3. Transport 4. Industry
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About GHGs
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1.3. PREDICTABLE AND UNPREDICTABLE CLIMATE CHANGE
PREDICTABLE AND UNPREDICTABLE CLIMATE CHANGE
• What climate scientists mean by predictability without having to read an entire book on
statistics! As you might guess, climate scientists use the word predictability a little differently
than the rest of the world.
• For instance, you might say that I am predictable because I take the same path each day on my
morning walk, with small variations.
• On the other hand, for a climate scientist concerned with predictability, the question is whether
it’s possible to forecast how my walk tomorrow will differ from its usual path.
• Predicting that I’ll take my usual path is a climatological forecast in the sense that it is based
only on the long-term average (climate) of past events. For a climate scientist, predictability is
all about how forecasts differ from the climatological forecast.
• In fact, if the climatological forecast of an event is the only forecast available, the climate
scientist will say that the event is unpredictable.
• So, my morning walk could be predictable to you but unpredictable to a climate scientist.
• A number of factors prevent more accurate predictions of climate change, and many of
these will persist
PREDICTABLE AND UNPREDICTABLE CLIMATE CHANGE
• While advances continue to be made in our understanding of climate physics and the response of the climate system
to increases in greenhouse gases, many uncertainties are likely to persist.
• The rate of future global warming depends on future emissions, feedback processes that dampen or reinforce
disturbances to the climate system, and unpredictable natural influences on climate like volcanic eruptions.
• Uncertain processes that will affect how fast the world warms for a given emissions pathway are dominated by
cloud formation, but also include water vapour and ice feedbacks, ocean circulation changes, and natural cycles of
greenhouse gases.
• Although information from past climate changes largely corroborates model calculations, this is also uncertain due
to inaccuracies in the data and potentially important factors about which we have incomplete information.
• It is very difficult to tell in detail how climate change will affect individual locations, particularly with respect to
rainfall.
• Even if a global change were broadly known, its regional expression would depend on detailed changes in wind
patterns, ocean currents, plants, and soils.
• The climate system can throw up surprises: abrupt climate transitions have occurred in Earth’s history, the timing
and likelihood of which cannot generally be foreseen with confidence.
PREDICTABLE AND UNPREDICTABLE CLIMATE CHANGE
• Despite these uncertainties, there is near-unanimous agreement among climate scientists that human-caused
global warming is real
• It is known that human activities since the industrial revolution have sharply increased greenhouse gas
concentrations; these gases have a warming effect; warming has been observed; the calculated warming is comparable
to the observed warming; and continued reliance on fossil fuels would lead to greater impacts in the future than if this
were curtailed.
• This understanding represents the work of thousands of experts over more than a century, and is extremely unlikely
to be altered by further discoveries.
• Uncertainty works in both directions: future climate change could be greater or less than present-day best
projections
• Any action involves risk if its outcomes cannot be foreseen and the possibility of significant harm cannot be ruled
out.
• Uncertainty about the climate system does not decrease risk associated with greenhouse gas emissions, because it
works in both directions: climate change could prove to be less severe than current estimates, but could also prove to
be worse.
• Even if future changes from greenhouse gas emissions are at the low end of the expected range, a high-emissions
pathway would still be enough to take the planet to temperatures it has not seen for many millions of years, well
before humans evolved. In this situation, there can be no assurance that significant harm would not occur.
• Science has an important role in identifying and resolving uncertainties and informing public policy on
climate change
• All societies routinely make decisions to balance or minimise risk with only partial knowledge of how these risks
will play out.
• This is true in defence, finance, the economy and many other areas. Societies have faced and made choices about
asbestos, lead, CFCs, and tobacco.
• Although each case has unique aspects, all carried scientifically demonstrated but hard-to-quantify risks, and were
contentious, in common with climate change.
• Mechanisms have been put in place nationally and internationally to facilitate scientific input into decision making.
In particular, the international Intergovernmental Panel on Climate Change (IPCC) has prepared thorough, ‘policyneutral but policy-relevant’ assessments of the state of knowledge and uncertainties of the science since 1990, with
the most recent assessment completed in 2014.
• Australian scientists have made a major contribution to the quality and integrity of these international IPCC
assessments.
QUIZ ONE
END OF UNIT ONE!!!!!
UNIT TWO Climate Change and Agriculture
• Chapter Two: Climate change and Agriculture
• 2.1 Climate change vs crop production
• 2.2 Climate change vs livestock production
• 2.3 Climate change and agriculture sector
• 2.4 Climate change and Industry sector
• 2.5 Climate change and Service sector
[6 Hr]
Climate change vs crop production ….
LECTURE 3
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END OF UNIT TWO!!!!!