FOOD security has been defined as "access by all people at all times to enough food for an active, healthy life".
The World Food Summit, in 1996 and in 2002 by the United Nations Food and Agricultural Organisation (FAO) highlighted the basic right of people to an adequate diet and need for concerted action among all countries to achieve this goal in a sustainable manner.
How vulnerable households, regions and countries are to climate change's impacts on agriculture will depend on their access to land, water, and government support and action. The evidence for climate change because of the actions of human being is overwhelming.
According to the IPCC's 4th assessment report (AR4), human-caused warming and rise in sea level "would continue for centuries" because the process has already started "even if greenhouse gas concentrations were stabilised".
The disturbing signs are already visible in rising seas, heat waves, worsening droughts and stronger hurricanes.
Water shortage, heat waves, storms and floods are likely to be the result of global warming caused by human actions.
Global temperatures are likely to rise by about 3 degrees Celsius by 2100.
The rise the "best estimate" of the scientists from a range of predictions between a rise of 2 degrees Celsius and 4.5 degrees C.
According to IPCC, the most significant and immediate consequences for small islands are likely to be related to rainfall regimes, soil-moisture budgets, prevailing winds, short-term variations in regional and local sea levels and patterns of wave action.
Observational data from various regions indicate an increase in surface temperature that is greater than global rates for the Pacific.
These are likely to have major effects on soil and water resources, which will have direct impacts on agriculture and food production.
While it seems logical that any changes in climate will affect agriculture and the world's food supply, access to adequate food is also a function of socio-economic factors.
Food security will depend on the inter-relationships between political and socio-economic stability, technological progress, agricultural policies and prices, growth of per capita and national incomes, poverty reduction, women's education, trade and climate variability.
Climate change, however, will affect food production because of shifts in temperature and rainfall, people's access to food by lowering their income from coastal fishing because of rising sea levels or lowering a country's foreign exchange earnings by the destruction of its export crops because of the rising frequency and intensity of tropical cyclones.
Overall, climate changes including global warming and increased climate variability, could result in a variety of impacts on agriculture.
Some of the impacts of climate change on food production which are already visible and seem to be increasing are: Increased heat stress to crop and livestock, e.g. higher night temperatures which could adversely affect grain formation and other aspects of crop development, Increased evapo-transpiration rate caused by higher temperatures and lower soil moisture levels, Concentration of rainfall into a smaller number of rainy events with increases in the number of days with heavy rain, increasing erosion and flood risks, Changes in seasonal distribution of rainfall, with less falling in the main crop growing season, Sea level rise, leading to coastal degradation and salt water intrusion,
Food production and supply disruption through more frequent and severe extreme events; Increased incidence of pests and diseases that will negatively affect crop production.
This increase will probably have different impacts in different regions.
Agricultural impacts are likely to be more adverse in tropical areas compared to that in temperate regions.
As climate change shifts, wheat production to the north across the globe may be beneficial for farmers in North America and Russia.
In contrast, many of today's poorest developing countries are likely to be negatively affected with a reduction in the extent and potential productivity of cropland.
Small developing states such as sub-Sahara Africa, are likely to be most seriously affected because of their inability to adequately adapt simply because of a lack of resources.
The projected increase in yields from northern countries will not be able to make up for declining production in the developing world.
In fact, the disparity between the rich and poor, the North and South and developed and developing countries could widen.
According to a report from the Consultative Group on International Agricultural Research, CGIAR, the dry weather will result in a shorter growing season and smaller crop yields across much of the developing world, challenging the livelihoods of billions of people.
The projected temperature increase and shift in rainfall patterns are likely to decrease growing periods in sub-Sahara Africa by more than 20 per cent, with some of the world's poorest nations in East and Central Africa at great risk. The new research shows warming will slash wheat production in India's bread basket.
Production will drop 50 per cent by 2050 a decrease that could put as many as 200 million people at greater risk of hunger.
"Developing countries which are already home to most of the world's poor and malnourished people and have contributed relatively little to the causes of global warming are going to bear the brunt of climate change and suffer most from its negative consequences," said Louis Verchot, a climate change scientist with the World Agroforestry Centre, one of 15 research centres allied under the CGIAR.
Given the low adaptive capacities of low-income groups, climate change will have greater impact on the livelihood of the poor. The rural dwellers generally have poor infrastructure and market distribution systems and have more land areas prone to floods and rising sea levels.
Coastal areas that comprise a significant economic zone for small islands face the possibility of degradation of fishing areas because of changes in salinity, temperature and sedimentation. There is evidence of increased flooding and salinisation of land traditionally used for sugar cane farming in Fiji.
Many areas used for taro in Pacific countries are becoming too saline for current varieties and the availability of fresh water for agriculture is being seriously compromised.
The main issue confronting agriculture is how to respond, adapt and be more resilient.
One of the ways of preventing the effects of global warming is to decrease the amount of carbon dioxide and other greenhouse gases into the atmosphere. However, even if all CO2 emissions stopped now, the amount of CO2 already emitted into the atmosphere would result in an enhanced greenhouse effect for the next 50 years. Thus, people will need to adapt to the effects of climate change. Adaptation can be defined as any action that seeks to reduce the negative effects, of climate change. Adaptive actions may be either anticipatory or reactive in nature. An example of an anticipatory adjustment is the development of heat and drought-tolerant crop varieties.
The levels of adaptation made by a region may have significant effects on how climate change will affect agriculture in that area.
A wide variety of adaptive actions may be taken to lessen or overcome adverse effects of climate change on agriculture.
Farmers can adopt coping mechanisms that withstand climate variability through activities such as the use of drought-resistant or salt-resistant crop varieties, the more efficient use of water resources and improved pest management.
Adjustments may include the introduction of later-maturing crop varieties, switching cropping sequences, sowing earlier, adjusting timing of field operations, conserving soil moisture through appropriate tillage methods and improving irrigation efficiency.
Options such as switching crop varieties might not be expensive while others such as irrigation entail major investments.
Changes in cultivation patterns can include the reduction of fertiliser use, better management of crop production, improvement of livestock diets and better management of their manure. In addition, governments have an important role to play in enforcing land-use policies which discourage slash and burn expansion, extensive livestock rearing and raising opportunities for rural employment. Considerable investment will be needed, however, to utilise soil and water resources more efficiently in a changed climate. Developing countries, particularly in the tropics and semi-tropics, are not well endowed with respect to research base and availability of investment capital.
There are, however, limits to adaptation. The potential for adaptation should not lead one to assume that the negative impacts on food access and security can be adequately cushioned. Agricultural adaptation to climate change and climate variability will never be a panacea. Changes in how farmers operate or what they produce may cause significant disruption for people in rural areas.
Indeed, some adaptive measures may have detrimental impacts of their own. For example, if major shifts in crops were to be made, as from sugarcane to fruit and vegetable production, farmers may find themselves more exposed to marketing problems and credit crises brought on by higher capital and operating costs.
While changes in planting schedules or in crop varieties may be readily adopted, modifying the types of crops does not ensure equal level of food production or nutritional quality, nor can it guarantee equal profit for farmers. Expanded irrigation may lead to groundwater depletion, soil salinisation and water-logging.
Increased demand for water by competing sectors may limit the viability of irrigation as an adaptation to climate change.
This is particularly critical for many island atolls where the availability of water for drinking is a serious issue. Expansion of irrigation as a response to climate change will be difficult and costly, even under the best circumstances. Mounting societal pressures to reduce environmental damage from agriculture will likely foster an increase in protective regulatory policies that can further complicate the process of adaptation. Adaptation cannot be taken for granted. Improvements in agriculture have always depended on the investment made in agricultural research and infrastructure. It would help to identify, through research, the specific ways farmers adapt to present variations in climate. Do farmers try to compensate for a less favourable climate by applying more fertiliser, machinery or more labour? Such information is needed to assess potentialities for coping with more drastic climate change. Success in adapting to possible future climate change will depend on a better definition of what changes will occur where and on prudent investments made in timely fashion, in adaptation strategies. To complicate matters, the availability for insurance generally and for agriculture in particular is a cause of major anxiety among many developing countries. It is known that the premium for insurance of properties have suddenly become almost unaffordable in Fiji, especially after the impacts of floods in the north and west.
Crop insurance sounds like a far cry in many developing countries but given the likely impacts on agriculture because of climate change, this possibility should no longer be regarded as a luxury.
Indeed, insurance for crops should be an adaptation option which should be seriously pursued.
Global warming may result in detrimental effects on food supply and security, especially in developing countries.
Even if developing countries adapt to climate change, they will not be able to completely avoid the problems associated with climate change.
One final thought there is often a misleading and blind faith in agriculture as a self-correcting process that through the forces of the market and self-preservation, farmers can readily and fully adapt to climate change.
They will make every effort to do so but their effort may be constrained or thwarted by factors beyond their control.
In the tropics, inadequate agricultural research, training and funding limit the capacity of farmers to adapt to climate change.
Even those who can afford changes, the end result in terms of production and income will not necessarily compensate the costs.
Dr Kumar is a specialist in environment, energy and sustainable development. He was Associate Professor of Physics and HOD Physics at the University of the South Pacific, served as technical specialist in climate change with the United Nations Environment Program and Secretariat of the Pacific Regional Environment Program.