Impacts of Climate Change on Agriculture - Climate Resilient Agriculture for Ensuring Food Security - page 47

Table 4.3 ( continued)

Sector Impact

Livestock Climate change will affect fodder production and nutritional security of livestock. Increased temperature

would enhance lignifi cation of plant tissues, reducing the digestibility. Increased water scarcity would
also decrease production of feed and fodder
Major impacts on vector-borne diseases will be through expansion of vector populations in the cooler
areas. Changes in rainfall pattern may also infl uence expansion of vectors during wetter years, leading to
large outbreaks of diseases
Global warming would increase water, shelter, and energy requirement of livestock for meeting the
projected milk demands
Climate change is likely to aggravate the heat stress in dairy animals, adversely affecting their reproductive
performance

Fishery Increasing temperature of sea and river water is likely to affect breeding, migration, and harvests of fi shes

Impacts of increased temperature and tropical cyclonic activity would affect the capture, production,
and marketing costs of the marine fi sh
Coral bleaching is likely to increase due to higher sea surface temperature

4.2 Carbon Dioxide (CO 2 )

Enrichment

widespread impact on long-term human health
if additional fertilizers were not incorporated
into crop production.
There are positive impacts of climate change
in agriculture and forestry because plants can
respond positively to higher concentrations of
CO 2 in the atmosphere (LaSalle and Hepperly
2008 ). Higher levels of CO 2 increase the rate of
photosynthesis and improve the effi ciency of
water use in plants, hence stimulating plant
growth (known as CO 2 fertilization). Experiments
where CO 2 concentrations have been increased
by around 50 % (to approximately 550 ppm)
have produced growth increases of around 15 %
(Niggli et al. 2009 ) in crops and 10-50 % in trop-
ical savanna grasses (US Geological Survey
2008 ). In studies where CO 2 has been increased
up to 700 ppm, wheat yields have risen by
10-50 %, cotton biomass by 35 %, whole boll
yields by 40 %, and lint yields by 60 % (Lal et al.
2003 ). Data supporting these conclusions have
been collected in major fi eld experimental stud-
ies in Australia (Wheat FACE experiment at
Horsham in Victoria and OZFace experiment in
Townsville, Queensland).

Increasing atmospheric CO 2 concentration and
simultaneous rises in temperature are infl uencing
the global climate, henceforth affecting growth,
development, and functioning of plants (Fig. 4.1 ).
The primary effects of increased concentration of
CO 2 include higher photosynthetic rate, increased
light-use effi ciency, reduction in transpiration
and stomatal conductance, and improved water-
use effi ciency (Drake et al. 1997 ).
Scientists are in agreement that the levels of
atmospheric CO 2 have increased in recent years.
Prior to the industrial revolution, they were
measured at 280 parts per million by volume
(ppmv); currently the levels are around 380
ppmv. These levels have been steadily increas-
ing by 1.9 ppm yearly since the year 2000,
largely as a result of fossil fuel burning. Carbon
dioxide is critical to photosynthesis (and thus
plant growth). Scientists agree that even small
increases in carbon dioxide result in more plant
growth. It is likely that higher levels of CO 2 will
result in higher harvestable crop yields.
However, this depends critically on the avail-
ability of suffi cient water and nutrients neces-
sary for plant growth. Some scientists believe
that one drawback to this increased productivity
will be crops with lower nutrient and protein
levels. If true, this could have a signifi cant,

4.2.1 Impact on Photosynthesis

CO 2 is vital for photosynthesis, and the evidence
is that increases in CO 2 concentration would