Climates can be classified using parameters such temperature and rainfall to define specific climate types. (Seiz, 2007)

According to Haeberli, (2008) from Montana State University, climate change is any long term significant change in the expected patterns of average weather of a specific region (or, more relevantly to contemporary socio-political concerns, of the earth as a whole) over an appropriately significant period of time.

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Susanne, and Veizer (2008) revealed that climate change reflects abnormal variations to the expected climate within the earth's atmosphere and subsequent effects on other parts of the earth, such as in the ice caps over durations ranging from decades to million of years.

Reports revealed by the inter-governmental panel on climate change (IPCC 2007) stated that climate change in the research of a great many factors including the dynamic processes of the earth itself, external forces including variation in sunlight intensity, and more recently by human activities, which might in future be deliberate geo-engineering. External factors that can shape climate are often called climate forcing and include such processes as variations in solar radiation, deviations in the Earths orbit and the level of greenhouse gas concentrations.

There have been so many variations on carbondioxide(Co2) during the last 50 million years. The increased carbondioxide level are thought to exacerbate the heating effects of the greenhouse effect by reading the re-radiation of heat from the sun and, therefore, increasing the temperature contained in the atmosphere.

As the ability of the atmosphere to capture and recycle energy emitted by the Earth's surface is essential to a stable climate, this heightened temperature may introduce a de-stabilizing influence and potentially affect global weather patterns and eventually, long-term climate change.

(Source: Buckley, and Wallace, 2008)

Framers efforts on yielding mass harvest and encouraging large plantation may be seriously terminated and hampered from the perception of climate change. Where alternative instruments are not introduced to counteract the factors militating against favourable climate on farm produce this may lay a set back on agricultural input and output by our farmers.

It obvioused that climate change had contributed towards initiating basic subsistence farming system order than the mechanized farming product for large market of farm produce.

For example, a region where climate change had hampered the possibility of regular actual rainfall variably, water system irrigation can be applied to artificially supply wet contents on crop growth and improving regular harvest.

Farmers in Nigeria today are faced with variable challenges on climate change making the agricultural sector prone to difficulties in enhancing crop production as a result of weak alternative facilities, equipments and scientific instruments to improve the range of farming.

Dr Daniel (2008) from the University of Maiduguri revealed findings that climate change plays a significant role in agriculture by setting up limits for crop production. The main climatic elements in agriculture are temperature, moisture, sunlight, wind and evaporation. Most crops are sensitive to episodes of high temperature. High temperatures between 45oc and 55oc that occur for at least 30 minutes directly, damage crop leaves in most environments, and lower temperatures between 35-40oc can be damaging if they persist longer.

Awosika, and Ajayi, (2002) opined that vulnerability of crops to damage by high temperatures varies with developmental stage thus, high temperatures during reproductive development are particularly injurious. For example, to maize at tussling, to soybean at flowering and to wheat at grain filling.`

Soybean in one of crops that seems to have the ability to recover from heat stress, perhaps, because it is in determinate.

Whereas as stated by Adefolau (2000) food crops like yam, cocoyam, potatoes, cassava can get damage (burnt) due to excessive heat temperature.

Precipitation, being the primary source of soil moisture is probably the most important factor determining the productivity of corps. While global climate models predict an overall increase in mean global precipitation, their results also show the potential for changed hydrological regimes in most places.

Ojo (2000) a change in climate can cause changes in total precipitation, within season pattern, and between season variability for crop productivity, a change in the pattern of precipitation events may be even more important than a change in the annual precipitation. The water regime of crops is also vulnerable to a potential rise in the daily rate and alerted seasonal pattern of precipitation events may be even more important than a change in the annual precipitation. The water regime of crops is also vulnerable to a potential rise in the daily rate and altered seasonal pattern of evapotranspiration, brought on by warm temperature, drier air, or windier conditions. Drought conditions may be brought about by lower amounts of precipitation falling.

Oni (2001) opines that farm produce and yield quantity are likely to suffer if dry periods occur during critical developmental stages. In most grain crops, flowering, pollination and grain filling are especially sensitive to water stress, heat stress and drought stresses often occur simultaneously one contributing to the other. High solar radiance and high winds often accompany these conditions. When crops are subjected to drought stress, their stomata close, such closure reduces transportation and consequently, raises plant temperatures. Excessively wet years, on the other hand, may cause farm produce declines due to water logging and increased pest infestation (Dr. Daniel, 2008).

Intense burst of rainfall may damage younger plants and promote water logging of standing crops with repining grain, as well as soil erosion. The extent of crop damage depends on the duration of precipitation and flooding, crop developmental stage, air and soil temperatures.