Climatic systems major components and implications in agricultural planning

Climatic Systems: Its Major Components

and Implications in Agricultural Planning

PRESENTERS: JACK ABEBE & ELIZABETH NJANI

Sunday, April 9, 2023 1

Definition

Climatic systems

Components of climatic systems

Agricultural Planning

Adaptation to climate change

References

“Research is a craft – It takes practice and more practice”


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.


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.



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)


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



OceansRivers

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.


the part of the climate system that includes all water on and around Earth

includes liquid water, water vapour, and ice


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


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)



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.


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



Land Surface Human Systems

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.


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.



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.


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.


Agricultural planning – strategic (long-term) and tactical (<10 days) – needs to weigh climate-related 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.


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 infor mation for both tactical and strategic decision-making.


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.


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 sched ules).


Climatic system is useful in the following areas of

agricultural planning


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.


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 differ ent crop varieties.

Agroclimatic characterization of crops includes solar radiation, temperature, humid ity and photoperiod, among the most important climatological factors


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 hardi ness of the varieties in the species.


A climatic system is important in land preparation as part of agricultural planning.

As far as frost protection is concerned, deep plough ing 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.


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.


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 long-term management strategy, and a good manager should be cognizant of those factors that threaten the sustainability and long-term financial viability of the property.


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).


Climate may also change outside the range of previ ous 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.


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 co-ordination 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.


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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Climatic systems major components and implications in agricultural planning

Business

earths water

liquid water

water vapour

subterranean water

saline water

climate system

frozen sea water

earths surface