The explicit focus of this book is on climate change - i.e. the potential shifts in the longer-run mean and extremes of temperature, precipitation, and other meteorological variables in a given area. And while longer-run climate exerts significant influence on agricultural decision-making, affecting what crops farmers grow and when and where they grow them, the actual amount of food produced in a given year depends on the specific realization of meteorological variables in that year. Year-to-year changes in these variables (or "climate variability") play a central role in global and regional food systems and in food security outcomes.
As a result, climate variability can both illuminate and constrain possible longer-run adaptation to climate change. For instance, farmer and food system responses to past weather events are some of the only evidence we have to understand how farmers respond to climate shifts. At the same time, variability also makes production more risky, which might inhibit risk averse farmers from undertaking broader adaptation measures. Finally, the year-to-year noise of climate variability might make it harder to recognize that climate is actually changing.
Observed farmer adaptations to climate variability fall into two main camps: ex ante measures, for which action is taken in anticipation of a given climate realization, and ex post responses, which are undertaken after the event is realized. Ex ante adaptations to variability often center around strategies of diversification, which attempt to capitalize on the differential effects that a given climate event might have on different crops and activities in a given year (Pandey et al. 2007). For instance, farmers growing rainfed crops in a drought-prone environment might seek to diversify the location of their farm plots to take advantage of the high spatial variability of rainfall, grow a range of crops or crop varieties with different sensitivities to climate, or to diversify income sources into non-farm enterprises that are less sensitive to climate (Pandey et al. 2007). They could also choose to maintain flexibility with regard to input decisions until uncertainties about weather realizations are reduced, for instance by shifting when crops are planted. Where possible, farmers might also pay to insure their harvests against failure.
Farmers also undertake various ex post strategies to decrease crop or welfare losses once climate events have been realized. Such strategies include drawing down cash reserves or stores of grain, borrowing from formal or informal credit markets or family, selling assets such as livestock, or migrating elsewhere in search for work in non-affected regions. Ex post adaptations can also include changes to management after the growing season has started, such as replanting of faster-maturing varieties if early-season planting fails, or irrigating where possible if rainfall is meager.
Not all strategies are available to all farmers unfortunately, nor are the available strategies always successful in buffering food security against a variable climate. In wealthier countries, farmers rarely go hungry as a result of drought or other adverse climate events. The existence of social safety nets and functioning financial markets ensure that farmers are either insured against losses, can borrow around them, or can receive help from the government to maintain livelihoods during bad times. Similarly, consumers in rich countries spend only a small percentage of their income on food, and are thus not very sensitive to the food price increases that often accompany droughts or floods.
The same is not often true in poor countries. Although both ex-post and ex-ante strategies can reduce climate-associated losses to some degree, the poorest households in particular are often unable to fully shield consumption from the effects of climate variability. This inability can be dramatic and devastating, as in the case of the drought-related famines in the Sahel and Horn of Africa in the 1980s, but they can also be more subtle, such as in the longer run documented negative effects of climate variability on health and economic outcomes in agricultural households, particularly for women and children (Hoddinott and Kinsey 2001; Maccini and Yang 2008). Such effects are realized because ex ante measures are insufficient, or ex post measures such as insurance or savings are unavailable, or both.
Also important are the perverse longer run effects of some of these adaptive measures on the food security of poor households. For instance, while ex ante strat egies can reduce the risk of catastrophic losses in bad years, they can also reduce the income earned in good years, because farmers might have planted a less-risky but lower-yielding (and typically lower-value) crop. The long-run costs in foregone income from this risk-mitigation can be high - as much as 15-30% of average income (Rosenzweig and Binswanger 1993; Dercon and R. World Institute for Development Economics, 2002). Similarly, ex-post strategies can also avoid devastating declines in consumption in ways that harm longer run earning potential. Distressed liquidation of productive assets such as livestock or land can prop up consumption in one year, but dampen the subsequent productivity and food access of households in later years, an effect again well documented in the developing world. These perverse temporal tradeoffs are a perennial and painful dilemma faced by farmers throughout much of the developing world.
Given the negative impacts of climate variability on economic livelihoods and food security in much of the developing world, helping farmers better adapt to this variability is a central concern of development. Many have also argued that a focus on adapting to climate variability is the best way to approach adapting to climate change. This is in part because most farmers and governments can more readily understand the threat of variability, and thus are more likely to engage in building knowledge and institutional capacity to cope with variability (Washington et al. 2006; Cooper et al. 2008). It is also because climate variability can have large effects on livelihoods, and thus that longer-run adaptations will only be undertaken if they do not compromise the ability to cope with variability.
But as climate change adds to the stress of variability, will existing coping mechanisms be enough to offset expected losses from climate change in the absence of adaptation? Are current strategies for adapting to variability appropriate strategies for adapting to longer-run climate change? If not, and novel adaptations are called for, should we expect farmers to adopt them on their own, or will significant investment and policy intervention be needed to adapt food production to new climates?
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Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.