Part I - Agriculture, food security and ecosystems: current and future challenges Module 2: Climate variability and climate change “CLIMATE-SMART” AGRICULTURE, an information package for government authorities. This online information package was written with the idea of providing an overview of the challenges that the agriculture sector - and to a certain extent the food production chain - faces to feed the world while becoming more efficient. It also explores ways to address these challenges. ©FAO

1. Module 2. Climate variability and climate change
CLIMATE-RESILIENT AND
ENVIRONMENTALLY SOUND AGRICULTURE
OR “CLIMATE-SMART” AGRICULTURE
Information package for government
authorities

2. Module 2. Climate variability and climate change
Introduction to the information package
The future of humankind and the planet relies on human activities becoming more
efficient, the food chain being no exception. This online information package was
written with the idea of providing an overview of the challenges that the agriculture
sector—and to a certain extent the food production chain—faces to feed the world
while becoming more efficient. It also explores ways to address these challenges.
Through simplified concepts and relevant resources and examples, we explore the
impacts of global change on agriculture, the impacts of agriculture on ecosystems
and possible technical and policy considerations that can help building food security
under current and future challenges.
The technical and policy considerations explored are meant to contribute towards
climate-resilient and environmentally sound or “climate-smart” agriculture—
agriculture that increases productivity; enhances resilience to global change; stops
ecosystem services deterioration; and produces economic and social benefits.
The information presented here comes from findings, experience and ideas from all
over the world, as we believe there are already elements to catalyse change. We
also believe this change has to come largely from local communities, for which
reason, wherever possible, we provide examples at local levels.
See how to use the information package.

3. Module 2. Climate variability and climate change
PART I
AGRICULTURE, FOOD SECURITY AND ECOSYSTEMS: CURRENT
AND FUTURE CHALLENGES
PART II
ADDRESSING CHALLENGES
PACKAGE CONTENT

4. Module 2. Climate variability and climate change
MODULE 2
CLIMATE VARIABILITY AND CLIMATE
CHANGE

5. Module 2. Climate variability and climate change
Module structure
Module 2. Climate variability and climate change
Objectives
The objective of this module is to summarise climate change concepts.
Structure
The module provides simple definitions of weather and climate; discusses climate
variability and climate change; gives some evidence of climatic change; and briefly
looks at projections of how climate may be for the rest of the century. Illustrations
are linked to files with a larger view, expanding on the topics covered, or providing
access to full text documents
Caveat
The information provided in this module provides comes from models which are
currently believed to be the best available but they need to be looked out with
caution as models are continuously refined.

6. Module 2. Climate variability and climate change
Climate and weather
• Climate and weather are different
• Weather is what happens in a given time (e.g. days or hours), climate is the
average weather over long periods
• Factors that can affect climate are called “climate forcing mechanisms”
Weather and climate are different. Weather is the conditions, such
as temperature, rain and wind that we see over short periods. These
can change hour by hour, day by day.
Climate can be thought of as the average weather over a long
period. It results from the interactions between the atmosphere,
oceans, ice sheets, land masses and vegetation. Scientists have
defined characteristic climate zones around the world (see map).
They give us an indication of the average climatic conditions of an
area, i.e. arid, warm temperate, polar, etc.
The factors that affect climate are called climate forcing
mechanisms; they can include variations in solar radiation,
deviations in the Earth's orbit, volcanic activity, continental drift, and
greenhouse gas concentrations.Köppen-Geiger Climatic
Classification.

7. Module 2. Climate variability and climate change
Climate and weather
Examples
“Climate is what we expect,
weather is what we get”
See the difference between
climate and weather in South
America:
South America's climate zones
range from dry steppe to
equatorial monsoon. It also
includes tropical, as well as
subtropical areas. Zones change
with altitude, with each altitudinal
zone displaying distinct local
climate, soils, crops, domestic
animals and modes of life (Figure
A).
The temperatures in South
America on a given day - “the
weather” (Figure B).
Figure A. Climate zones
in South America.
Note the classification
differs slightly from
Köppen-Geiger.
Figure B. Weather in
South America.
Temperatures on 13
August, 2011.
Source: The Weather
Channel.

8. Module 2. Climate variability and climate change
Climate variability
• Climate varies naturally at different time and spatial scales
• Climate variability can manifest periodically or suddenly
The Earth's climate is dynamic and naturally varies at different time
scales, e.g. within months, seasons, decades or larger scales. It
also varies regionally or globally. Each "up and down" fluctuation
can lead to conditions which are warmer or colder, wetter or drier,
more stormy or quiescent. Some regions experience greater
variability than others. More…
El Niño (a variation in the Pacific oceanic temperatures) and the
Southern Oscillation (a variation in surface air pressure over the
western Pacific Ocean) are examples of climate variability.
Climate variability is manifested in other ways as well. Decadal and
seasonal shifts in wind patterns and sea surface temperatures in the
Atlantic cause changes in hurricane frequency. Changes in volcanic
activity can also change temperatures. Sometimes climate varies in
ways that are random or not fully explainable. More…
The Asian monsoon from space.
Photo: NASA image STS51F-31-069.

9. Module 2. Climate variability and climate change
Climate variability
Examples
Mount Pinatubo, in the Philippines,
erupted in 1991. Gases and ash
reached an altitude of about 34 km
and covered over 400 km in a few
hours. They were dispersed over the
whole planet within a year. The
“cloud” over the Earth caused global
temperatures to vary, temporarily
reducing them by 0.5 °C between
1992 and 1993.
There is evidence that suggests the
eruptions of the Laki craters in
Iceland (1783–1784) affected the
weather in Europe; weakened
African and Indian monsoon
circulations; and resulted in 1–3
millimetres less of daily precipitation
than normal over the Sahel of Africa
(Oman et al., 2006).
Mount Pinatubo eruption.
Source: U.S. Geological Survey Fact Sheet 113-97.
Photo: Roderick Batalon.

10. Module 2. Climate variability and climate change
Climate variability
Examples
In Central America climate variability
translates into droughts and floods
caused by tropical storms and
hurricanes.
According to the Comisión
Centroamericana de Desarrollo y
Medio Ambiente (CCDA /SICA),
between 1930 and 2008, 248 severe
weather events were recorded in the
region, with 85% being floods,
tropical storms and landslides, 9%
droughts, 4% forest fires and 2%
extremes in temperatures (mainly
low temperatures).
Honduras is the country which
experienced the highest climate
variability during this period.
Aerial shots of damage by Hurricane Mitch to agricultural land: palm
crops covered in mud.
Photo: FAO/L. Dematteis.

11. Module 2. Climate variability and climate change
Climate variability
Reflections
Ethiopia provides a good example of
the influence of climate variability on
a developing country’s economy.
GDP in Ethiopia rises or falls about a
year behind variations in average
rainfall (see figure).
With agriculture accounting for half of
GDP and 80% of jobs, the Ethiopian
economy is sensitive to climate
variability, particularly variations in
rainfall.
Source: Adapting to climate variability and change, USAID and Ethiopia
- Managing water resources to maximize sustainable growth: Water
resources assistance strategy, The World Bank.
Is your country sensitive to climate
variations? You could consult your
national statistics institute for rainfall
records together with GDP data and
find out if there is any relation.

12. Module 2. Climate variability and climate change
Weather disasters and extreme events
• Extreme weather events are rare
• Weather disasters—not necessarily extremes in climatic statistical terms—result
in ecological and economic losses
• Weather disasters could reduce global GDP by up to 1%
Although the term “extreme weather event” was reserved for events
that statistically were rare (occur with a frequency below 5%), the
term is increasingly used to refer to weather events that result in
disasters.
Information on the few extreme weather events recorded in history
can be found in the World weather/climate extremes archive
maintained by The World Meteorological Organization and Arizona
State University (USA).
Weather disasters, which result from large departures from average
weather conditions—but not necessarily climatic statistical
extremes—result in ecological and economic losses. It is estimated
that weather disasters could reduce global GDP by up to 1%.
Weather disasters can include, for example, severe: heat and cold
waves, tornadoes, dust storms, droughts, tropical cyclones, floods.
Khulna in August 2010. A home
still flooded by Cyclone Aila,
which swept through Bangladesh
in May 2009.
Photo: FAO/M. Uz Zaman.

13. Module 2. Climate variability and climate change
Weather disasters and extreme events
Examples
Weather disasters in the
United States of America
The United States of
America, through its
National Climatic Data
Center (NCDC), keeps a
record of weather
disasters.
The U.S.A. has sustained
108 weather-related
disasters over the past
31+ years for which costs
reached or exceeded
US$1 billion. The total
normalised losses for the
108 events exceed
US$750 billion.
Reports from the U.S. National Climatic Data Center on weather disasters costing
more than US$1 billion during 1980–2010.
Source: National Climatic Data Center.

14. Module 2. Climate variability and climate change
Weather disasters and extreme events
Examples
Drought in East Africa
By the end of August 2011,
the worst drought in 60
years in the Horn of Africa
had sparked a severe food
crisis and high malnutrition
rates, with parts of Kenya
and Somalia experiencing
pre-famine conditions.
More than 10 million
people were affected in
drought-stricken areas of
Djibouti, Ethiopia, Kenya,
Somalia and Uganda and
the situation continued
deteriorating..
A pastoralist stands near a carcass in Sericho, Kenya. He used to walk 5 km
with the herd to find pasture, but the distance is now 30–50 km.
Photo: Tran Ngoc Huyen.

15. Module 2. Climate variability and climate change
Weather disasters and extreme events
Reflections
The publication Weather extremes
in a changing climate: Hindsight on
foresight has a series of examples of
weather disasters all over the world
from 2000 to 2010.
Heat waves, floods, droughts, bush
fires, cold spells were prominent and
all continents were affected. These
events cost millions of dollars all over
the world.
Photos: Adapting to climate change and climate variability, USAID;
Ethiopia - Managing Water Resources to Maximize Sustainable Growth:
Water Resources Assistance Strategy, WB; Dimaberkut; FAO/Asim
Hafeez.
Have there been weather disasters
associated with your area? Which
type? Do they seem to show a pattern?
How have they varied in the last
decade? Do you know what are the
costs of each event?

16. Module 2. Climate variability and climate change
Climate change
• Climate change implies sustained changes over decades
• Changes have been more marked in the last 3 decades and are associated with
human activities
Climate change implies sustained changes (over several decades
or longer) to the average values for climate variables such as
temperature, precipitation, winds or atmospheric pressure. These
changes are normally detected as trends, for example, a trend of
global warming, sea level rise or reduction of snow cover (See
figures and explanations via the links).
Data gathered over the 30-year period from 1961 to 1990 define the
latest Normals used for climate reference. Scientists have observed
changes in the last decades compared to these values. There is
evidence that these changes have been mainly caused by human
activities, through an increased greenhouse effect, and that these
changes are occurring at a faster rate than ever.
Scientists have been monitoring these changes; reports of their
findings can be found on the IPCC website.
Observed changes in climate.
Source: IPCC Climate Change
2007: Synthesis report .

17. Module 2. Climate variability and climate change
What is the greenhouse effect
• The atmosphere and greenhouse gases (GHGs) control the temperature of
Earth; without them the Earth would be much cooler
• Human activities are increasing GHG concentrations and the planet is warming
faster than ever
The planet and its atmosphere absorb and reflect the solar energy
reaching it. The balance between absorbed and reflected energy
determines the average temperature.
The atmosphere and certain gases stop the heat from escaping into
space. They allow the sun’s energy through, but stop it from
escaping back into space, acting like a greenhouse. The gases
producing this effect, such as water vapour, carbon dioxide and
methane, are called Greenhouse Gases (GHGs).
Without the greenhouse effect, the Earth would be 30 °C cooler,
making it uninhabitable for most forms of life.
Unfortunately human activities are increasing the concentration of
GHGs in the atmosphere and amplifying the greenhouse effect,
trapping more and more heat and increasing global temperatures. A
1 or 2 °C increase could drastically change the life on the planet.
Emissions of long-lived GHGs
from 1970 to 2004.
Source: IPCC Climate Change
2007: Synthesis Report.

18. Module 2. Climate variability and climate change
Observations on climate change
• IPCC scientists are in agreement that climate change is unequivocal
• Scientists have gathered evidence for changes in temperature, hydrosphere and
extremes
According to the IPCC, climate warming is unequivocal. Examples
of evidence of the climate changing include (see also the figure):
Temperature
• Surface temperatures increased by about 0.74 °C between 1906
and 2006.
• Observations since 1961 show that the average temperature of
the global ocean has increased to depths of at least 3,000 m.
Hydrosphere
• Satellite data since 1978 show the annual average ice cover in
the Arctic sea has shrunk by an average 2.7% per decade, with
larger decreases in summer of an average 7.4% per decade.
• Global average sea level rose at an annual average of 1.8 mm
(1961 to 2003) and 3.1 mm (1993 to 2003).
Monthly Palmer Drought Severity
Index (PDSI) for 1900 to 2002.

19. Module 2. Climate variability and climate change
Observations on climate change
Examples
Changes in the Yellow
River Basin.
Obvious climate changes
have been observed over
the past decades in the
Yellow River Basin. The
mean annual temperature
has risen continuously,
especially since the
1990s, while precipitation
and runoff have
consistently decreased.
The frequency and
intensity of climate events
has also changed in
recent years .
Mean annual temperature between 1961 and 2004 recorded in Menyuan
station, one of the meteorological stations along the Yellow River Basin.
Source: The China Climate Change Partnership Framework - Final Report.
Menyuan station
Temperature°C

20. Module 2. Climate variability and climate change
Observations on climate change
Reflections
In 2009, the Mexican government reported in its 4th National
Communication to the UNFCCC that from 1971 the
country’s temperature increased by an average 0.6 °C. With
the last 10 years indicating an accelerated warming of
0.7 °C. These data are in agreement with global findings.
Temperature changes between 1971 and
2008 in Mexico.
Source: Instituto Nacional de Ecología .
Are you aware of observations for your country or region?
How do they compare to global observations?
You may be able to find data in the National
Communications to the UNFCCC, your Environment
Ministry, local universities or regional research centres.

21. Module 2. Climate variability and climate change
Projecting future GHG emissions
• Scientists use models and scenarios to study potential future greenhouse gas
emissions and associated impacts on climate
• If better policies are not introduced, the concentration of GHGs in the
atmosphere will continue to increase
Scientists use computer models and scenarios (or assumptions
about the future) to study the way that emissions and climate would
change under different development paths.
The IPCC uses the Special Report on Emissions Scenarios
(SRES), which groups scenarios into families A1, A2, B1 and B2.
These explore “story lines” or alternative development pathways,
covering a wide range of demographic, economic and technological
driving forces. The SRES scenarios do not include additional
climate policies. Post-SRES scenarios have refined assumptions
but this has only minor effects on overall emissions.
At the moment there is high agreement that if better climate change
mitigation policies and related development practices are not
introduced, global GHG emissions will continue to grow over the
next few decades (see graph).
Global GHG emissions (in GtCO2-
eq per year) in the absence of
additional climate policies.
Source: IPCC, SyR-3.

22. Module 2. Climate variability and climate change
How will climate be in the future?
• Continued GHG emissions can cause further warming, with larger changes than
those observed for the 20th century
• Temperature, precipitation, snow cover, sea level will change and weather events
are expected to increase in frequency and magnitude
Continued GHG emissions can cause further warming and induce
many changes in the global climate during the 21st century. These
changes could be larger than those observed during the 20th
century, for example:
• Temperatures will continue to increase.
• Warming would be greatest over land, especially at northern
latitudes, and least over the Southern Ocean (near Antarctica)
and northern North Atlantic, continuing recent observed trends.
• The area of snow cover will contract.
• Sea ice is expected to shrink in both the Arctic and Antarctic
under all SRES scenarios.
• Sea level might rise 0.18–0.59 m (without considering ice
melting).
• Hot extremes, heat waves, cyclones and heavy precipitation
events may become more frequent and intense.
Relative changes in precipitation
for the period 2090–2099,
relative to 1980–1999.
Source for both: IPCC Syr-3.
Projections of global surface
warming.

23. Module 2. Climate variability and climate change
How will climate be in the future?
Examples
Using projections to know how
countries could be affected
Projections for sea level rise (SLR)
are controversial, due to the
contribution of many factors. Some
countries are exploring what could
happen under different SLR
projections. According to the Arab
Forum on Environment and
Development, a SLR of only 1 m
would flood much of the Nile Delta,
inundating about one third of the
land. Coastal cities such as
Alexandria, Idku, Damietta and Port-
Said would be at risk. In this case, it
is estimated that about 8.5% of
Egypt’s population will be displaced
(see figure for other projections).
Remote sensing and GIS analysis depict areas of the Nile Delta at risk of 1
m to 5 m sea level rise.
Source: Impact of Climate Change on Arab Countries.

24. Module 2. Climate variability and climate change
How will climate be in the future?
Reflections
Click here to find a summary of the most
recent climate regional projections
according to the Fourth Assessment
Report of the IPCC.
Temperature anomalies, observations and projections at continental
level.
Source: IPCC, Contribution of Working Group I to the Fourth
Assessment Report of the Intergovernmental Panel on Climate Change,
2007.
What are the IPCC projections for
your region?
Regional projections are very coarse
(or low resolution); are you aware of
downscaling models for your area?
Areas to look for would be differences
in temperature, precipitation, water
availability, sea level rise,
desertification, ice cover changes,
weather events.
If available, make a list of the
projections for your area.

25. Module 2. Climate variability and climate change
Resources
References used in this module and further reading
This list contains the references used in this module. You can access the full text of some of
these references through this information package or through their respective websites, by
clicking on references, hyperlinks or images. In the case of material for which we cannot
include the full text due to special copyrights, we provide a link to its abstract in the Internet.
Institutions dealing with the issues covered in the module
In this list you will find resources to identify national and international institutions that might hold
information on the topics covered through out this information package.
Glossary, acronyms and abbreviations
In this glossary you can find the most common terms as used in the context of climate change.
In addition the FAOTERM portal contains agricultural terms in different languages. Acronyms of
institutions and abbreviations used throughout the package are included here.

26. Module 2. Climate variability and climate change
Please select one of the following to continue:
Part I - Agriculture, food security and ecosystems: current and future challenges
Module 1. An introduction to current and future challenges
Module 2. Climate variability and climate change
Module 3. Impacts of climate change on agro-ecosystems and food production
Module 4. Agriculture, environment and health
Part II - Addressing challenges
Module 5. C-RESAP/climate-smart agriculture: technical considerations and
examples of production systems
Module 6. C-RESAP/climate-smart agriculture: supporting tools and policies
About the information package:
How to use
Credits
Contact us
How to cite the information package
C. Licona Manzur and Rhodri P. Thomas (2011). Climate resilient and environmentally sound agriculture
or “climate-smart” agriculture: An information package for government authorities. Institute of Agricultural
Resources and Regional Planning, Chinese Academy of Agricultural Sciences and Food and Agriculture
Organization of the United Nations.

27. Module 2. Climate variability and climate change