2 Climate Change and the Availability of Food
The first widely-circulated attempt to assess the effects of climate change on global
agriculture was the model published by Cline (2007). This work is notable because
of its use of a range of climate scenarios and its discussion of the potential yield
effects on major crop staples. In the years that followed, major efforts took place to
build the assumptions that underlay Cline’s work into more robust models that were
sensitive to a wider array of variables.
Models subsequent to Cline have understood climate change not simply in terms
of shifts to temperature gradients, but its embodiment of a range of different
weather-related events. This is an important development, because in different
regional agricultural-climate interfaces, it may be that non-temperature effects
related climate change—such as shifts to the volume, timing and distribution of
precipitation, or increased exposure to extreme weather events—may have critical
impacts on the viability of crop and livestock production. Research in northern
India, which we will discuss further below, has highlighted the dramatic effects of
these factors in combination.
Knowledge about the relationship between climate change and agricultural
production was expanded considerably by the World Bank-sponsored work of
Müller et al. (2010). In addition to the modelling of climate per se, this model also
incorporated potential effects of CO 2 fertilization (the effects of enhanced CO 2 in
stimulating plant growth) in forecasting climate-agriculture interactions. Müller
et al. were open-minded on the effects of CO 2 fertilization, painting a range of
potential effects, noting that it was ‘the most important factor’ (p. 3) in uncertainty
over climate change effects. This accorded with knowledge at the time, which
proposed that increased CO 2 in the context of a changed climate may actually
generate a net positive effect on agricultural yields. Since 2010, however, consensus
has shifted such that any positive effects from CO 2 fertilization would be outweighed by net negative implications from climate change (Hemming et al. 2013).
In AR5-WG II, fertilization effects were noted as being highly variable, based on
plant type and agro-ecological context, and in general, rather less important than
other factors in the determination of agricultural production responses to a changed
climate. This position was summarized aptly by The Guardian at the time of the
release of AR5-WG II, which observed: “While plants like carbon dioxide, they
don’t like heat waves, droughts, and floods” (Nuccitelli 2014).
By 2014, the accumulation of research based on experiments and field trials
across the world allowed the IPCC to synthesize 66 yield-impact studies on the
effects of climate change on major cereal crops for both tropical and temperate
regions (IPCC 2014: 497–499). The focus on cereals is pertinent given that a few
major cereal crops (rice, wheat and maize) contribute approximately 40 % of
humanity’s dietary energy. With temperature increases of 1–2 degrees over
pre-industrial averages, yields in the tropics are forecast to begin to decline. In
temperate zones, the negative effects of climate change kicked-in once temperatures
were 3–5 degrees above pre-industrial averages. More recent evidence further
The Impacts of Climate Change for Food and Nutrition Security: …
13
The first widely-circulated attempt to assess the effects of climate change on global
agriculture was the model published by Cline (2007). This work is notable because
of its use of a range of climate scenarios and its discussion of the potential yield
effects on major crop staples. In the years that followed, major efforts took place to
build the assumptions that underlay Cline’s work into more robust models that were
sensitive to a wider array of variables.
Models subsequent to Cline have understood climate change not simply in terms
of shifts to temperature gradients, but its embodiment of a range of different
weather-related events. This is an important development, because in different
regional agricultural-climate interfaces, it may be that non-temperature effects
related climate change—such as shifts to the volume, timing and distribution of
precipitation, or increased exposure to extreme weather events—may have critical
impacts on the viability of crop and livestock production. Research in northern
India, which we will discuss further below, has highlighted the dramatic effects of
these factors in combination.
Knowledge about the relationship between climate change and agricultural
production was expanded considerably by the World Bank-sponsored work of
Müller et al. (2010). In addition to the modelling of climate per se, this model also
incorporated potential effects of CO 2 fertilization (the effects of enhanced CO 2 in
stimulating plant growth) in forecasting climate-agriculture interactions. Müller
et al. were open-minded on the effects of CO 2 fertilization, painting a range of
potential effects, noting that it was ‘the most important factor’ (p. 3) in uncertainty
over climate change effects. This accorded with knowledge at the time, which
proposed that increased CO 2 in the context of a changed climate may actually
generate a net positive effect on agricultural yields. Since 2010, however, consensus
has shifted such that any positive effects from CO 2 fertilization would be outweighed by net negative implications from climate change (Hemming et al. 2013).
In AR5-WG II, fertilization effects were noted as being highly variable, based on
plant type and agro-ecological context, and in general, rather less important than
other factors in the determination of agricultural production responses to a changed
climate. This position was summarized aptly by The Guardian at the time of the
release of AR5-WG II, which observed: “While plants like carbon dioxide, they
don’t like heat waves, droughts, and floods” (Nuccitelli 2014).
By 2014, the accumulation of research based on experiments and field trials
across the world allowed the IPCC to synthesize 66 yield-impact studies on the
effects of climate change on major cereal crops for both tropical and temperate
regions (IPCC 2014: 497–499). The focus on cereals is pertinent given that a few
major cereal crops (rice, wheat and maize) contribute approximately 40 % of
humanity’s dietary energy. With temperature increases of 1–2 degrees over
pre-industrial averages, yields in the tropics are forecast to begin to decline. In
temperate zones, the negative effects of climate change kicked-in once temperatures
were 3–5 degrees above pre-industrial averages. More recent evidence further
The Impacts of Climate Change for Food and Nutrition Security: …
13