Climate change is caused by both natural and human factors such as greenhouse gas emissions and fossil fuel burning. It is leading to rises in global temperature, changes in precipitation patterns, more extreme weather events. These changes are negatively impacting agriculture through reduced crop yields, shifts in suitable farming areas, and increased pest and disease pressures. While some factors like carbon dioxide fertilization may slightly increase yields, the overall impacts of climate change on global agriculture are expected to be severely damaging to food production and security.

1. CLIMATE
CHANGE AND
ITS IMPACT
ON
AGRICULTURE

2. MEANING OF CLIMATE CHANGE
“It is a change which is attributed directly
or indirectly to human activity that alters
the composition of the global atmosphere
and which is in addition to natural climate
variability observed over comparative time
periods”

3. CAUSES OF CLIMATE
CHANGE
Natural Anthropogenic
• Volcanic eruption
• Solar variation
• Variation in ocean
currents
•Greenhouse gases
•Burning of fossil
fuels
•Industrial Pollution

4. EFECT OF CLIMATE
CHANGE
Rise in sea level
Rise in temperature
Changes in precipitation
patterns
More droughts and heat waves
Hurricanes become stronger
and more intense

6. HOW CLIMATIC CHANGE COULD
AFFECT AGRICULTURE
Productivity,
in terms of
quantity and
quality of
crops
Agricultural
practices,
through
changes of
irrigation and
agricultural
input.
Environmenta
l effects, in
particular soil
drainage, soil
erosion ,
reduction of
crop
diversity.
Rural space,
through the
loss and gain
of cultivated
lands.
Adaptation,
organisms may
become more
or less
competitive, so
that humans
may develop
more
competitive
organisms.

7. DIRECT IMPACT OF CLIMATE
CHANGE ON AGRICULTURE
Changes in mean
climate
•Extreme temperatures
•Drought
•Heavy rainfall and flooding
•Tropical storms
Climate variability
and extreme
weather events

8. CHANGES IN MEAN CLIMATE
Changes in the mean climate away from current states may require
adjustments to current practices in order to maintain productivity,
and in some cases the optimum type of farming may change.
Higher growing season temperatures can significantly impact
agricultural productivity, farm incomes and food security.
Increasing evaporative demand owing to rising temperatures and
longer growing seasons could increase crop irrigation requirements
globally by between 5 and 20 percent.
Water is vital to plant growth, so varying precipitation patterns have a
significant impact on agriculture.

9. EXTREME TEMPERATURES
Changes in short-term temperature extremes can be critical,
especially if they coincide with key stages of development.
Only a few days of extreme temperature (greater that 32°C) at the
flowering stage of many crops can drastically reduce yield.
In the short-term high temperatures can affect enzyme reactions and
gene expression.
In the longer term these will impact on carbon assimilation and thus
growth rates and eventual yield.

10. DROUGHT
Drought can
cause poor
germination
and impaired
seedling
development
in plants.
Drought
stress
impairs
mitosis and
cell
elongation
which results
in poor
growth.
Drought
stress lead to
a decrease in
leaf size and
number.
Crop plants
exposed to
drought
stress suffer
from
reductions in
leaf water
potential and
transpiration

11. HEAVY RAINFALL AND FLOODING
Heavy rainfall events leading to flooding can wipe out
entire crops over wide areas, and
Excess water can also lead to other impacts including
soil water logging, anaerobicity and reduced plant
growth.
Indirect impacts include delayed farming operations.
Agricultural machinery may simply not be adapted to
wet soil conditions.

12. TROPICAL
STORMS
Although many studies
focus on the negative
impacts, tropical cyclones
can also bring benefits.
In many arid regions in the
tropics, a large portion of
the annual rain comes from
cyclones.
Tropical cyclones can also
help replenish water

13. INDIRECT IMPACTS OF CLIMATE
CHANGE ON AGRICULTURAL
Pests and diseases
Mean sea-level rise
CO2 fertilization
Ozone

14. PESTS AND DISEASES
Research has shown that climate change may alter
the developmental stages of pathogens that can affect
crops.
Due to climate change the geographical distribution
of hosts and pathogens could shift, which would result
in more crop losses.
This could affect competition and recovery from
disturbances of plants.

15. MEAN SEA-LEVEL RISE
Increases in mean sea level threaten to inundate
agricultural lands and salinize groundwater in the
coming decades to centuries.
Sea-level rise can be expected to eventually cause
inundation of coastal land, especially where the capacity
for introduction or modification of sea defences is
relatively low or non-existent.
Regarding crop productivity, vulnerability is clearly
greatest where large sea-level rise occurs in conjunction
with low-lying coastal agriculture.

16. CO2 FERTILIZATION
Increasing atmospheric CO2 concentrations can directly
affect plant physiological processes of photosynthesis
and transpiration.
Elevated CO2 increases crop yields and growth through
an increase in photosynthetic rate.
It also decreases water loss as a result of stomatal
closing.
Rising levels of carbon dioxide reduces the
concentrations of protein and essential minerals in most

17. OZONE
Ozone reduces agricultural yield through several
mechanisms.
Firstly, acute and visible injury to products such as
horticultural crops reduces market value.
Secondly, ozone reduces photosynthetic rates and
accelerates leaf senescence which in turn impacts on
final yield.