Transcript Slide 1

Impact of agriculture on climate change
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Agriculture and forestry are responsible for about 30% of
greenhouse gas emissions through
 loss of carbon from soils and vegetation
 agricultural activities that produce GHGs such as
methane (CH4) and nitrous oxides (NOx)
Growing demand for food is the dominant driver of the
development and expansion in agriculture and
deforestation
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An indicator of available food in the world is the amount
of grains (cereals) available
Focus on three main cereal crops: maize, wheat, and
rice because they supply half of the energy required by a
person
An active, healthy adult requires 2000 to 3000 Calories
per day
 note: 1 Calorie = 1000 calorie = 1 kcal
 Malaysia: 2,901 Calories per capita
calorie content (per 100 g):
 maize = 355, rice = 325, wheat = 341
 vegetables and fruits = < 100
 potatoes = 77
Land use trends
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Agriculture land covers 5 billion hectares (about onethird or 35% of Earth’s ice-free land area)
 1.5 billion ha of cropland (11% of the Earth's ice-free
land surface)
 3.5 billion ha of rangeland (pasture) (25%)
Changes have occurred between forested land to
agricultural land (cropland and rangeland) due to
increase in the world population and the demand for food
Over the last 40 years agricultural land has increased by
about 500 million hectare (Mha) or 10%
 half of this increase came from deforested land
Global agricultural cropland area distribution
Ramankutty, N.; Evan, A.T., Monfreda, C. and Foley, J.A. (2008). "Farming the planet: 1. Geographic
distribution of global agricultural lands in the year 2000". Global Biogeochemical Cycles 22: GB1003.
Global agricultural rangeland area distribution
Ramankutty, N.; Evan, A.T., Monfreda, C. and Foley, J.A. (2008). "Farming the planet: 1. Geographic
distribution of global agricultural lands in the year 2000". Global Biogeochemical Cycles 22: GB1003.
Bert Metz, 2010, Controlling Climate Change, Cambridge University Press, Cambridge
Challenges and effects
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The following are the challenges faced by agriculture
today, and how they cause, either directly or indirectly,
detrimental climate change:
1. Falling crop productivity
2. Over-dependency on fossil fuel (oil) for energy
3. Increasing demand for meat
4. Increasing world population
5. Competition between food and biofuel crops
6. Deforestation
Falling crop productivity
Green Revolution
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In the 1950-60s, poor yields in India, Africa, and Mexico
caused problems of world food shortages and
starvations
But in the late 1960s, Green Revolution brought huge
increases in crop yields primarily through improved crop
varieties
 Mexico: wheat yields 6x more than 1944 yields
 India: wheat yields 2x more between 1965-72
As a result, world famine was greatly alleviated as there
was plentiful of food (with the exception of some parts
in Africa), and food prices fell
To many governments, it appeared then that our
problem of food supply was over
Diminishing returns
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Grain yields increased impressively throughout the
1970s and 1980s, but since then, yield increases are no
longer as large as they once were
Grain production per person, for instance, peaked at 346
kilograms in 1984, fell to less than 300 kilograms today,
and is expected to be at 247 kilograms in 2020
Before 1984, total grain production increased 3% per
year. Now, it is increases at average of 1.6% only
OUTPUT
approaching the end, smaller increases
at the beginning, large increases
INPUT
Falling increase in world crop productivity
3.5
3.0
3.2
2.7
2.5
2.0
2.2
2.0
2.1
2.0
1.8
1.7
1981-2000
1.3
1.5
1961-1980
2001-2008
1.0
0.5
0.0
Maize
Rice
Wheat
Biological limit
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It appears we have reached the limits of Green
Revolution
Extra fertiliser and water brought increased yields but
with diminishing returns (not as high or as dramatic as
before)
Plants, given their current physiology and genetic
makeup, can only produce so much
Adding increasingly more inputs only continues to push
against the ceiling—the plant’s photosynthetic limits
 biological limit: further inputs will no longer enhance
yields or smaller increases
Over-dependency on fossil fuel for energy
50-year dependency on oil
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Oil is the lifeblood of the global economy
Agriculture is heavily dependent on oil
 fertilizers, herbicides, and pesticides
 fuel for machinery
 fuel for transportation
 food processing
 electricity
 especially for controlled climate conditions
 hydroponics, aeroponics, artificial lighting, egg
incubators, other machinery
High inputs
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Agriculture is heavily dependent on inputs such as
fertilizers and pesticides (including herbicides) to
increase and protect crop yields
 typically over one-third of the total cost of farm
expenditure
Fertilisers and pesticides are made from fossil fuels
Nitrogen is one major nutrient for plant growth, but N
exists as inert (very stable) gas
To make nitrogen fertilizer (like urea), high temperature
and pressure needed to break apart the N2 gas (break
the triple bond)
 where to get that energy to produce that high
temperature and high pressure to break the bonds?
 answer: fossil fuel
Fertiliser use
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The use of fertilisers for the world, for instance,
increased by 55% from 1971 to 2007
 in just ten years from 1995/96 to 2005/06, the fertiliser
use in Malaysia increased by a staggering 66%,
making it one of the largest rise in the world
In 2009: 3.5 billion tonnes of fertilizers imported by
Malaysia, of that amount:
 90% is for oil palm
 5% is for rubber and cocoa
 5% is for vegetables, rice, and fruits
Worldwide fertiliser use
http://www.nytimes.com
Pesticide use
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Worldwide, pesticide use increases 2 to 5 percent
annually
Malaysia sees a slightly higher increase of 3 to 9 percent
each year
 Malaysia has one of the highest pesticide use per
hectare of agriculture land in the world (more than 23
kilograms of active ingredient per hectare), second
only to South Korea in the Asia region
 world average is only 2 kg active ingredient per
hectare
“Food miles”
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Food miles
 total distance the food has to travel to reach the
consumers
Lots of food shuttling
 very dependent on transportation = more dependency
on fossil fuels
 favourite food items such as apples, oranges and
grapes, to name just a few, are commonly seen in the
Malaysian market all year round. Such food items are
transported over long distance, often by airfreight,
from their respective countries to reach our shores
 Inefficient food distribution system that means
wasteful and expensive use of energy
US food transportation
http://attra.ncat.org/attra-pub/foodmiles.html
Increasing world population
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World population currently stands at about 6.7 billion and
is expected to rise to about 9 billion in 2050 after which
world population will decline gradually
http://www.census.gov/ipc/www/idb/worldpopgraph.php
After rapid increases from 1900s to 1960, world population growth rate is now declining.
In 2008, world population growth rate is 1.17%
http://upload.wikimedia.org/wikipedia/en/1/13/World_population_growth_rates_1800-2005.png
World population density (2006)
persons per square kilometer
Malaysia: 84 persons per square km (2008 data)
http://www.mapsharing.org/MS-maps/map-pages-worldmap/6-world-map-population-density.html
City lights, Aug 15, 2003
http://science.nasa.gov/
World total fertility rate (TFR)
Years
TFR
Years
TFR
1950–1955
4.92
2000–2005
2.67
1955–1960
4.81
2005–2010
2.56
1960–1965
4.91
2010–2015
2.49
1965–1970
4.78
2015–2020
2.40
1970–1975
4.32
2020–2025
2.30
1975–1980
3.83
2025–2030
2.21
1980–1985
3.61
2030–2035
2.15
1985–1990
3.43
2035–2040
2.1
1990–1995
3.08
2040–2045
2.15
1995–2000
2.82
2045–2050
2.02
projected
Malaysia’s fertility rate
Malaysia has the same fertility rate as the world average
http://data.worldbank.org
Malaysia’s statistics
Malaysia Population
30.0
million people
25.0
20.0
15.0
10.0
5.0
0.0
1960
1970
1980
1990
2000
2010
2020
Year
• one birth for every 58 seconds
• one death for every 4 minutes and 36 seconds
• one gain on net migration (International) for every 5 minutes and 15 seconds
• overall increase in population, one person for every 56 seconds
• annual increment rate: +1.7%
Increasing demand for meat
Increasing demand for meat
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From 1950 to 2000, meat intake per person grew from
17 to 38 kg per year
The richer a nation, the more meat they eat!
 likewise, the richer you are, you eat more meat
 a country with a growing economy would see higher
demand for meat
About one third of world grain production is diverted to
livestock feed, away from human consumption
 our food going to animals, but feed efficiency is low
 1 kg animal feed does not give us 1 kg of meat
Food fed to animals are made from grain (corn, rice, and
wheat)
 For every 1 kilogram of beef, pork and chicken costs
7, 4 and 2 kilograms of grain feed, respectively.
Meat production
http://newscientist.com/
(Rich) China’s meat demand
1970
2008
China
Europe
US
China
Europe
US
4
49
56
89
124
89
Annual meat demand (kg per capita)
China: from 4 to 49 kg per capita; 12 times increase in 38 years!
World average is 38 kg per capita
Malaysia’s food consumption
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By 2020,
 Beef consumption to increase from 0.26 kg per capita
in 2005 to 0.45 kg per capita
 Chicken consumption per capita to double
From 1985 to 2000,
 Rice consumption declined 16%
 Wheat consumption increased 9% from 1985 to 2000
 Fruit, vegetable and fish consumption doubled
 Chicken and beef consumption increased by 141 and
121%, respectively
Competition between food and biofuel crops
Biofuels
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Food crops grown for fuel
Starch and cellulose from corn, sugar cane, cassava,
coconut, wheat, sorghum, and soybean
 transesterification process to convert starch and
cellulose into ethanol
Oil palm and jatropha
 oil extracted as biodiesel (also a biofuel)
 oil palm has the highest oil production
http://www.nrel.gov
Jatropha
http://www.bayercropscience.com/
http://www.treeoilsindia.com/
Previously considered as a weed.
Seeds and leaves are poisonous.
http://www.biodieselnow.com/b/site/archive/2009/06/17/daily-news-06-17.aspx
40 N/S
20 N/S
L/ha
L/ha
http://www.thebioenergysite.com/articles/571/biodiesel-the-sustainability-dimensions
Biofuel = carbon neutral?
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If harvesting is done sustainably, biofuel does not
contribute to emissions
 CO2 is taken up in the vegetation
 burning causes CO2 emission
 so, no net CO2 emission: intake CO2 = outgoing CO2
But in reality this sustainability assumption is not met
because of disturbance or fossil fuel use for
maintenance, harvesting, and processing
 so biofuel can have a +ve net CO2 emission: emit
more CO2 than that absorbed during photosynthesis
High oil prices = more demand for biofuel crops
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High fuel prices have made the cultivation of biofuel
crops extremely attractive
 forests are cleared for biofuel crops
 in farms, increasingly more tracts of land are
dedicated to growing biofuel crops, reducing the land
acreage that would otherwise be used to grow food
 before: all land area is for growing crop for food
 now: some land area is for growing crops for food,
and the other is for fuel
 so, less food available
In other words, there is a competition between biofuel
and food crops
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The amount of corn required to fill up an SUV (Sports
Utility Vehicle) tank just once is equivalent to feeding a
person in Africa for one whole year
If 100% jet fuel in a plane comes from oil palm biodiesel:
 every 1 km flight requires biodiesel from 2 or more oil
palm trees
 to support the world aviation industry for a year, the
total land area needed for oil palm is larger than
whole of Malaysia
Deforestation
Deforestation
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Net loss of forest area (7.3 Mha/year) is the result of the
difference between
 deforestation on average about 12.9 Mha/year
between 2000 and 2005 and
 the increase in newly forested areas about 5.7
Mha/year
The largest losses are found in South America, Africa,
and South-East Asia
Most of the increase in forestation is in Europe and East
Asia (China)
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% managed forested land
 90% in Europe
 10% in developing countries
Forest plantations only cover about 3% of the total
forested area, but are growing by almost 3 Mha/year
About 30% of all forest land is degraded
Deforestation in Malaysia
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Malaysia is over 58% covered by forest
 UK – 12% forested
 Australia – 21%
 France – 28%
 USA – 33%
 Germany – 32%
The land area of Malaysia is merely 0.25% of the total
land area in the world, but yet this tiny area contains
over 10% of the world’s plant species and 7% of the
world’s animal species
Tropical rainforests like ours contain the largest store of
carbon (and nutrients) than other forest types
In short, our rainforests are more precious than others
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Malaysia deforestation statistics (2010)
 Forest area: 19.324 million ha (58.6% of land area)
 Mean deforestation rate: 68,400 ha per year
Malaysia’s forest area is less than 0.5% of total forest
area in the world
 but we contribute 13% of the world’s deforestation
Malaysia’s deforestation rate is also equivalent to the
forest size clearing of 11 football (or soccer) fields per
hour
Malaysia loses about 0.19% of her forest annually
 Malaysia would be reduced to 50% forest cover by
2057
GHG emissions
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Agricultural lands and forest represent enormous
reservoirs of CO2, in the form of organic matter and
wood
The amount of carbon stored in forest biomass and soils
is larger than what is contained in the atmosphere
 much of that carbon is underground
So GHG emissions are not only determined by activities
that generate emissions, but also by the loss or gain in
these carbon reservoirs
Bert Metz, 2010, Controlling Climate Change, Cambridge University Press, Cambridge
Bert Metz, 2010, Controlling Climate Change, Cambridge University Press, Cambridge
Bert Metz, 2010, Controlling Climate Change, Cambridge University Press, Cambridge
Emissions from agriculture
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Emissions from agriculture consist predominantly
 methane (CH4) from animals, manure, and rice
production
 nitrous oxide (N2O) from nitrogen fertilizer application
N2O emissions from fertilized soils is the largest source
(38%), followed by methane production in animals
(32%), burning of crop residues (12%), rice fields (11%),
and manure (7%)
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Although there are large amounts (fluxes) of CO2 going
into agricultural crops and soils, there are equally large
fluxes going out (digestion and decomposition of
agricultural crops and crop residues)
 thus, the net flux is therefore small
Total CH4 and N2O emissions are about 6.2 Gt CO2-eq
per year
Net CO2 emissions due to the slowly decreasing carbon
content of agricultural soils are less than 1% of that
amount
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Magnitude and relative importance of CH4 and N2O
depends on regional differences
Because of the importance of agriculture in developing
countries and the large population, these countries are
responsible for about 75% of all emissions in the world
Emissions from manure are biggest in developed
countries
 large livestock populations in Latin America, Eastern
Europe, and Australia and New Zealand make this
the dominant source in those regions
Tropical agriculture
Trumper, K., Bertzky, M., Dickson, B., van der Heijden, G., Jenkins, M., Manning, P. June 2009. The Natural Fix? The role of ecosystems in
climate mitigation. A UNEP rapid response assessment. United Nations Environnent Programme, UNEPWCMC, Cambridge, UK
Nitrogen cycle
Fluxes (red) are in teragrams (1 Tg = 1012 g = 109 kg = 106 ton = 1 mil. ton) N/year
Industrial nitrogen fixation is the production of nitrogen fertilizer from N2 by the chemical
Haber-Bosch process.
As carbon dioxide rises, food quality will decline without careful nitrogen management by Arnold J. Bloom, California Agriculture
63(2):67-72, 2009
Emissions from forestry
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Emissions from the forestry sector are predominantly
caused by
 loss from the large carbon reservoirs through
deforestation and forest degradation (loss of trees
due to selective logging or other disturbance)
 decomposition of wood residues
 emissions of CH4 from burning
 emissions of N2O from
 fertilized managed forests or forest plantations
(about 5.8 Gt CO2/year)
 dewatering and oxidation or burning of
(deforested) peat lands (about 2.7 Gt CO2/year)
Trumper, K., Bertzky, M., Dickson, B., van der Heijden, G., Jenkins, M., Manning, P. June 2009. The Natural Fix? The role of ecosystems in
climate mitigation. A UNEP rapid response assessment. United Nations Environnent Programme, UNEPWCMC, Cambridge, UK
Trumper, K., Bertzky, M., Dickson, B., van der Heijden, G., Jenkins, M., Manning, P. June 2009. The Natural Fix? The role of ecosystems in
climate mitigation. A UNEP rapid response assessment. United Nations Environnent Programme, UNEPWCMC, Cambridge, UK
Peat lands
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Peat lands are water logged, high organic soils produced
by accumulation of rotting vegetation
In many countries a significant part of peatlands has
been dewatered and is used for agriculture or forest
plantations
Agriculture and forestry are responsible for 80% of peat
land loss
 peat harvesting for fuel or soil supplement
 urbanization
 infrastructure
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Dewatered peat land produces CO2 emissions through
oxidation of organic material and through fires that keep
burning underground
 largest losses are now happening in Indonesia and
Malaysia
 fires are responsible for about 2 Gt CO2/year
Bert Metz, 2010, Controlling Climate Change, Cambridge University Press, Cambridge
Trumper, K., Bertzky, M., Dickson, B., van der Heijden, G., Jenkins, M., Manning, P. June 2009. The Natural Fix? The role of ecosystems in
climate mitigation. A UNEP rapid response assessment. United Nations Environnent Programme, UNEPWCMC, Cambridge, UK
Wood products
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Wood products are a temporary storage of carbon
Wooden houses and other structures and furniture form
a carbon reservoir of the order of 5 GtC
 very small amount compared to what is stored in
vegetation and soils
Since wood products, including paper, have an average
lifetime of about 30 years, the accumulation of carbon in
wood products is limited
Wood products therefore have a very small contribution
to emissions
Changes in rainfall pattern from deforestation
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Deforestation also changes the rainfall pattern
 with forest, ¼ of rain ends up at rivers or oceans, and
¾ is recycled back into the atmosphere
 without forest, ¾ of rain ends up at rivers or oceans,
and ¼ is recycled back into the atmosphere (the
opposite occurs)
 less recyclable water available, eventually less rain,
and less water for humans/animals/plants
 over-pumping of water from aquifers
Summary
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Increasing population and income (wealth) pushes up
the demand for food and meat
Increasing oil prices increases the demand for biofuel
which competes (and reduces) available food
Global grain demand is projected to increase by 75%
between 2000 and 2050 and global meat demand is
expected to double
More than three-quarters of growth in demand in both
grains and meat is projected to be in developing
countries
All these mean greater expansion of agriculture needed
to meet those demands
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But greater expansion of agriculture means greater use
of fossil fuels (e.g., electricity, transportation, fertilizers,
pesticides, machinery) and more deforestation (opening
up of new agricultural lands)
Estimated another 400 – 500 Mha additional agricultural
land will be needed between today and 2020, even if
crop productivity were to improve further
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Ultimately, more agriculture would lead to greater GHGs
emissions and detrimental climate change
Total GHG emissions from agriculture and forestry are
now about 14.7 Gt CO2-eq/year, approximately 30% of
the global total
 however, this figure is uncertain (could be several Gt
higher or lower) because many of the emissions are
not easily measured, such as N2O from grasslands,
CH4 from rice production or savannah burning, and
CO2 from peat land, and forest degradation
The emissions from agriculture is expected to go up from
the current 6.2 to 8.3 Gt CO2-eq/year by 2030