Agriculture Reference
In-Depth Information
Chapter objectives
This chapter describes climate variability and how it can be measured using remote sensing
information. It defines climate variability, describes global trends in the temperature record
over the past 50 years and describes how these trends are likely to impact temperature. Remote
sensing of vegetation is presented as an alternative to precipitation datasets, to ensure compa-
rability and reliability in regions with few weather stations. Analysis of the growing season is
presented using vegetation data, and an example of how models assessing variations in growing
conditions can be used to estimate national-level food production is presented. Finally, an
assessment of the impact of development and agricultural investment on vulnerability to
climate variability is used to remind the reader of the effect of resources on outcome.
Climate, climate variability and climate change
Climate is the average weather over many decades in any one location. Climate variability and
change are often used interchangeably, but here they have distinctly different meanings. Climate
change refers to any statistically significant and persisting change in the mean state of the climate
over a long period of time (typically 30 years or longer). The Intergovernmental Panel on
Climate Change (IPCC) has defined climate change being change attributable to human activ-
ity. Climate variability refers to the variations in the mean state and other variations on temporal
and spatial scale beyond those of individual weather events. Variability may result from natural
internal processes within the climate system (internal variability) or from variations in natural or
anthropogenic external forces (external variability) (IPCC, 2007b). In this topic, I have chosen
to focus on climate variability, since the time period over which climate change occurs is too
long to be easily integrated with the rapid change in household vulnerability and the economic
context in which food security crises occur. Understanding the impact of climate and climate
variability on food availability and food access over a period of the last decade and the next will
require highly accurate observations of weather and climate, and an understanding of economic
and social context in which these shocks occur (NAS, 2004).
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