Agriculture Reference
In-Depth Information
technology, has enabled humanity to produce enough food for all. Although there are
droughts and other extreme climate events in any one year, the sheer scale and diversity of
the agriculture system has protected global production from these variations. Local com-
munities, however, can be profoundly affected by these short-term events, and if their vul-
nerability to changes in production is high, then even brief climate perturbations can have a
long-term impact (Simelton et al ., 2012; Bindraban and Rabbinge, 2012; Ericksen et al .,
2011). The drivers of change and vulnerability to climate include technology transformation,
expansion of population and dietary preferences. Table 3.1 describes the proximate drivers of
global environmental change that show the connection between human activities and the
resulting environmental impact.
Agriculture is a major contributor to environmental change, as it drives land use, atmos-
pheric pollutants of methane and nitrogen oxides, water pollution, biodiversity loss and other
effects (Lashof et al ., 1997). Global societal transformation has multiple, cascading effects on
natural systems at a variety of scales (Shindell et al ., 2012; Reid et al ., 2005). Steffen et al.
(2012) provide a broad overview of these changes and their interaction with social systems for
interested readers. Our focus in this topic is on agriculturally relevant climate variability that
has been measured with the satellite remote sensing data record over the past three decades,
and how these changes impact agriculture and ultimately food availability. Satellite data
represents an enormous improvement in our knowledge of weather and climate globally, but
there is still much that we need to know that we are still unable to measure. These include
the impact of farmer management, the yield potential of the crop being grown, the impact of
stress on plant activity and performance throughout the growing season, and geographically
and time specific information on what crops are being grown where. These gaps in know-
ledge revolve around being able to identify and quantify trends through time in order to
understand changes that are affecting society.
The extreme drought seen in Texas in 2011 is an excellent example of these questions.
The American southwest experienced the worst drought in 45 years, with high temperatures
and very low rainfall, starting in January 2011. The drought, which spread from Arizona to
Florida, hit central and northern Texas the hardest, with virtually no rain and significantly
above average temperatures for the first six months of the year. Was this drought part of a
broader drying trend that is likely to re-occur, or was it a one-time anomaly that won't be
repeated within our lifetime? This question is central to the policy and technical response to
the event, because some short-term responses to the drought can actually increase vulner-
ability if the drought is one of many instead of being a rare event. This is particularly true for
food security and humanitarian response. Emergency food aid can be destructive both of local
agricultural economies as well as to longer-term strategies to reduce vulnerability, e.g., out-
migration, income diversification and adoption of new technologies in agriculture (Barrett
and Maxwell, 2005). On the other hand, if no response occurs to a crisis, large-scale degrada-
tion of social and economic capital may occur. Thus the question of stability of a climate
record and its ability to capture both the current state as well as long-term trends is central to
the discussion of remote sensing information in this chapter.
Agriculturally relevant climate trends
Although most rainfed agricultural crops are sensitive to variations in temperature and precipita-
tion, and suffer yield losses during extreme weather such as high winds, tropical storms and fire,
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