Changes in soil water availability, the increased occurrence of climate fluctuation, climate extremes and crop diseases, could lead to an overall reduction in crop yield and serious food shortage. Projections suggest that by the end of the 21stcentury, climate variability would have had substantial impact on crop production (Slater et al 2007). Humanity cannot accurately predict what the next season will bring but farmers, input suppliers, marketers and government would all like to know because it is critical to decision making. Climate variability has created uncertainties in temperature, rainfall and wind patterns. As a result, rural people in countries like Nigeria whose main occupation or economic activity is agriculture, are faced with so many challenges in decision making with respect to their agricultural activities ( Barnwal and Kotani, 2010).

Climate variability adaptation methods according to Nyong, Adesina and Osman-Elasha (2007) are those strategies that enable the individual or the community to cope with or adjust to the impacts of the change in climate. Although, Zeirvogel et al (2008) had noted that the world has been undergoing series of adaptation in response to climate variability; the current climate change is expected to present heightened risk, new combinations of risks and potentially grave consequences. As such, adaptation has been identified as a policy option to mitigate the adverse effects of climate variability on farm productivity. In agriculture, adaptation helps farmers achieve their food, income and livelihood security objectives in the face of changing climatic and socio-economic conditions including climatic variability, extreme weather conditions such as droughts, floods and volatile short term changes in local and large scale markets (Kandlinkar and Risbey, 2000).

Agricultural adaptation has been described as one of the policy tools to ameliorate the ravaging effects of climate variability ( Kurukulasuriya and Mendelsohn, 2008). Mendelsohn and Dinar reported in 1999 that from farm level analysis, large reductions in adverse impacts from climate variability are possible when adaptation is fully implemented (FAO, 2007). Some adaptation strategies for crop production among farmers include adoption of efficient environmental resources management practices such as the planting of early maturing crops, mulching, small scale irrigation, adoption of hardy varieties of crops, tree planting and staking to avoid heat burns (Nyong, et al, 2007). There are lots of challenges facing agricultural adaptation in Nigeria. According to Nzeh and Eboh (2011) lack of awareness and knowledge on climate variability is perhaps the biggest obstacle to effective agricultural adaptation. Onyeneke and Madukwe (2010) also opined other barriers to include lack of information on appropriate adaptation option, poor access to market and shortage of farm labour.

Apata et al (2010) reported that capital, land and labour serve as important factors for coping with adaptation, stressing that the lack of these factors as well as choice of suitable adaptive measures constitute severe challenge to agricultural adaptation. This is consistent with Deressa et al (2008) report that adaptation to climate variability is costly, and the need for intensive labour use exacerbate this cost. This therefore calls for development of various adaptation strategies in order to cope with the variability in climate. Such strategies focus on managing risks, reducing vulnerability, enhancing agricultural productivity, protecting the environment and ensuring sustainable development under the changing climate.

1.2 Statement of the Problem

Recent studies confirm that Africa is one of the most vulnerable continents to climate variability and change and low adaptive capacity. Some adaptation to current climate variability has been taking place; however, this may be insufficient for future changes in climate (IPCC, 2007). The uncertainty associated with climate variability is a disincentive to investment and adoption of agricultural technologies and market opportunities, prompting the risk-averse farmer to favour precautionary strategies that buffer against climatic change, particularly as a result of increased variability and extreme over activities that are more profitable on average (Barrett et al, 2007). It has been predicted that many farmers in Africa are likely to experience net revenue losses as a result of climate change, particularly as a result of increased variability and extreme events (TerrAfrica, 2009).

The adverse consequences of climate variability includes damage on arable lands, livelihoods and biodiversity will take an irreplaceable toll on food production in developing countries like Nigeria which have a low capacity to cope and adapt to these challenges (Sha, Fischer van Velthuizen, 2009). Given the foregoing challenges a study of this nature will be a timely intervention. Many studies have been carried out in addressing the effects of climate variability on agriculture in Nigeria. However, not many of these studies have fully addressed the issues of adaptation strategies. Enete and Amusa (2011) discussed the challenges of agricultural adaptation to climate change in Nigeria, but the study was based on review of relevant literature thus leaving a gap for more empirical approach to the study of this issue.Enete and Amusa (2011) in another paper made further attempts to investigate the most cost-effective and sustainable indigenous climate change adaptation practices in South East Nigeria but studies covering wider area such as Nigerian agro-climatic zones and several arable crops simultaneously appear not to have been documented yet.

Umoh and Eketekpe (2010) attempted to study climate change adaptation measures by wetland farmers in Niger Delta region of Nigeria but did not study any other State beyond Bayelsa out of the nine States in the Niger Delta. The study focused only on a single Local Government Area. The study of Emaziye (2013) was based on perceptions of climate change among rural farming households in the Niger Delta area of Nigeria in other todetermine the direction of change of the climate change indicators thus leaving a gap for empirical studies on adaptation especially in Delta State where little or no work on adaptation strategies has been done. Previous studies showed that the dimensions of use of these measures have not been effectively explored particularly in Delta State. This is considered important, considering the fact that farmers least able to adapt to climate variability will suffer most severely.

In the light of this, this study has addressed the following research questions:

What are the socio-economic characteristics of crop farmers?

What is the perception of crop farmer's about climate variability?

What are the adaptation strategies adopted by farmers to mitigate the effects of climate variability?

What socioeconomic and environmental factors influence farmers' choice of adaptation strategies?

What factors constrain farmers in adapting to the effects of climate variability?