Climatic systems major components and implications in agricultural planning

Climatic Systems:
Its Major Components
and Implications in
Agricultural Planning
PRESENTERS: JACK ABEBE & ELIZABETH NJANI

Thursday, November 14, 2013

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Definition

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Climatic systems

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Components of climatic systems

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Agricultural Planning

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Adaptation to climate change

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References

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Climate is traditionally defined as the description
in terms of the mean and variability of relevant
atmospheric variables such as temperature,
precipitation and wind.
 Climate can thus be viewed as a synthesis or
aggregate of weather.
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A climatic system is an interactive system consisting of five
major components:
the atmosphere,
the hydrosphere,
the cryosphere,
the land surface
and the biosphere, forced or influenced by various external
forcing mechanisms, the most important of which is the
Sun.
Also the direct effect of human activities on the climate
system is considered an external forcing.


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Climate change refers to a statistically significant
variation in either the mean state of the climate or
in its variability, persisting for an extended period
(typically decades or longer).
 Climate change may be due to natural internal
processes or external forcing, or to persistent
anthropogenic changes in the composition of the
atmosphere or in land use.
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The atmosphere is the most unstable and rapidly
changing part of the system.
the layers of gases surrounding Earth
these gases reach more than 100km above the Earth’s
surface; beyond this height they are present in very low
concentrations
Air: 78% - Nitrogen Gas, 21% - Oxygen Gas
1% - Other (i.e. Argon, Carbon Dioxide, and traces of
Helium, Hydrogen, and Ozone)


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this proportion of gases changes at different
levels in the atmosphere
 the atmosphere reflects some of the Sun’s
energy, absorbs and radiates some of the
energy, and transmits some of it to the Earth’s
surface
 once the energy of the Sun reaches Earth’s
surface, the atmosphere traps much of it,
warming Earth
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Oceans

Rivers


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The hydrosphere is the component comprising all
liquid surface and subterranean water, both fresh
water, including rivers, lakes and aquifers, and
saline water of the oceans and seas.
 Fresh water runoff from the land returning to the
oceans in rivers influences the oceans
composition and circulation.
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the part of the climate system that includes all
water on and around Earth
 includes liquid water, water vapour, and ice
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energy is absorbed when water evaporates from
the oceans and lakes, this process has the effect
of cooling its surroundings
 energy is given off when water vapour condenses
into clouds in the atmosphere, this process warms
the surroundings
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large bodies of water have an effect on the climate
of nearby regions
 water absorbs and stores more thermal energy
than land, it also eats up and cools down more
slowly than land
 regions near an ocean or large lake tend to be
cooler in the summer than inland locations (the
water takes a long time to warm up as it absorbs
thermal energy), they also tend to be warmer in
the fall (as the water slowly emits stored thermal
energy)
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The cryosphere, including the ice sheets of
Greenland and Antarctica, continental glaciers
and snow fields, sea ice and permafrost, derives
its importance to the climate system from its high
reflectivity (albedo) for solar radiation, its low
thermal conductivity, its large thermal inertia and,
especially, its critical role in driving deep ocean
water circulation.


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Ice and the Climate System
 about 2% of all Earth’s water is frozen
 most of this ice located at the two poles
 sea ice or pack ice, only a few meters thick,
formed from frozen sea water, floats in the ocean
near the North and South Poles
 surfaces covered in ice and snow reflect more
radiant energy than surfaces covered in soil, rock,
or vegetation


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Land Surface

Human Systems


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Vegetation and soils at the land surface control
how energy received from the Sun is returned to
the atmosphere.
 Some is returned as long-wave (infrared)
radiation, heating the atmosphere as the land
surface warms.
 Some serves to evaporate water, either in the soil
or in the leaves of plants, bringing water back into
the atmosphere.
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Because the evaporation of soil moisture requires
energy, soil moisture has a strong influence on the
surface temperature.
The texture of the land surface (its roughness)
influences the atmosphere dynamically as winds blow
over the land’s surface.
Roughness is determined by both topography and
vegetation. Wind also blows dust from the surface into
the atmosphere, which interacts with the atmospheric
radiation.


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The marine and terrestrial biospheres have a
major impact on the atmosphere’s composition.
 The biota influences the uptake and release of
greenhouse gases.
 Through the photosynthetic process, both marine
and terrestrial plants (especially forests) store
significant amounts of carbon from carbon dioxide.
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Thus, the biosphere plays a central role in the
carbon cycle, as well as in the budgets of many
other gases, such as methane and nitrous oxide.


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Agricultural planning – strategic (long-term) and
tactical (<10 days) – needs to weigh climaterelated and other risks to attain the producer’s
goals and to spell out the sort of information that
farmers need to aid their planning, such as
climate, technical/managerial, and market data,
for example.


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A key aspect needed in linking climate and
weather risk to agricultural planners is an
appreciation of the overall management system in
question from the decision-makers’ viewpoint.
 Managers need information for both tactical and
strategic decision-making.
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As an example, an Australian survey of agricul
tural planners provided a myriad of planning
horizons and key decisions (sometimes referred to
as “decision points”) that could be influenced by
weather and climate variability at different
timescales. In addition, it has been realized that
the decision system extends across the whole
value chain in agricultural production that is
affected by weather and climate variability.


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The sugar industry can serve as an example that
has relevance to many agricultural planning
systems:
 there are decisions at the farm scale (irrigation,
fertilization, fallow practice, land preparation,
planting, pest management) and at the transpor
tation and milling scale (improved planning for wet
season disruption, planning for season start and
finish, crop size forecasts, civil works schedules).



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Climatic system is useful in
the following areas of
agricultural planning


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The method of selecting crop varieties based on
agroclimatic requirements consists of comparing,
on the one hand, the regional availability of agro
climatic resources and, on the other, the climatic
requirements of certain crop varieties on the basis
of which the selection is to be made.


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The selection of varieties of plants at local or
regional levels should be based on agroclimatic
studies carried out to determine the climatic
requirements of the different crop varieties.
 Agroclimatic characterization of crops includes
solar radiation, temperature, humidity and
photoperiod, among the most important
climatological factors
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Intraspecific variability for resistance to drought,
frost and heat stress is often large. Hence, there is
often room for plant breeding for resistance to
these risks. For example, in citrus growing, frost
may not be avoidable; however, selecting for
tolerance to sub-zero temperatures is a valuable
option (Ikeda, 1982). The selection of an
appropriate variety for a given area should take
into account the frost hardiness of the varieties in
the species.


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A climatic system is important in land preparation
as part of agricultural planning.
 As far as frost protection is concerned, deep
ploughing has about the same effect as shallow
ploughing on heat transfer, since the layer of soil
that is involved in heat transfer to the surface by
conduction, on a daily basis, is not thicker than
about 0.3 m.
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This is an important aspect of agricultural planning
as soils should be moist before a frost period is
likely to occur.
 Hence, irrigation one or two days in advance of a
frost night brings the soil to near field capacity,
which results in an increased soil heat flux during
a subsequent frost night.
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Climate systems are useful in pasture and
livestock management. An essential part of
farming in a variable climate is anticipating and
preparing for the next drought.
 This need to be incorporated into a farm’s longterm management strategy, and a good manager
should be cognizant of those factors that threaten
the sustainability and long-term financial viability
of the property.
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Knowledge of climate variability can assist in
adapting to climate change.
 In eastern Australia there is a strong correlation
between the Southern Oscillation Index in winter
and spring and subsequent spring and summer
rainfall (McBride and Nicholls, 1983; Stone et al.,
1996; Nicholls, 1998).
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Climate may also change outside the range of
previous experience, especially with regard to the
severity and frequency of extreme conditions.
 Longer-term adaptation will require some
foreknowledge of the nature of the climate
change, not simply reliance on recent experience.
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Brohan P., J.J. Kennedy, I. Harris, S.F.B. Tett SFB, and
P.D. Jones (2006). Uncertainty estimates in regional and
global observed temperature changes: A new data set
from 1850. J. Geophys. Res. 111 (D12): D12106.
Climate and Cryosphere (Clic) project science and coordination plan (2001). Edited by I. Allison, R.G. Barry
and B.E. Goodison.WCRP-114 WMO/TD No. 1053.
Cushman-Roisin, B. (1994). Introduction to geophysical
fluid dynamics. Prentice Hall, London, 319pp.


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Hartmann D.L. (1994). Global physical
climatology.International Geophysics series, volume
56.Academic Press, 412 pp.
IPCC (2007): Climate Change 2007: The Physical
Science Basis. Contribution of Working Group I to the
Fourth Assessment Report of the Intergovernmental
Panel on Climate Change [Solomon, S., D. Qin, M.
Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor
and H.L. Miller (eds.)]. Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA.


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THE END

THANK YOU FOR YOUR ATTENTION


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Climatic systems major components and implications in agricultural planning

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