Environmental Engineering Reference
In-Depth Information
2009b). As with livestock, impacts on fisheries are still very uncertain, but a
recent study suggests that if global average warming were to be 2°C, catch
potential could rise by 30-70% in high latitudes and fall by up to 40% in
the tropics, as commercial species shift away from the tropics as the ocean
warms (Cheung et al., 2010).
Food Prices and Food Security
One of the strengths of a global food system is that shortfalls in one area
can be offset by surpluses in another. Models of the global food economy
suggest that trade will represent an important but not complete buffer against
climate change-induced yield effects (Easterling et al., 2007). Specifically,
the comparative advantage will shift toward regions currently below opti-
mum temperatures for cereal production (e.g., Canada) and away from hot
tropical nations, with greater flows of food trade from north to south. On
average, studies suggest small price changes for cereals up to 2.5°C global
temperature increase above pre-industrial levels, with significant increases
for further warming, but there is considerable uncertainty around these
estimates (see Box 5.2).
Implications of climate change for hunger, or the more technical term—
food insecurity—follow in part from price changes, but also depend criti-
cally on how sources of income and other aspects of health are affected
by climate. A useful rule of thumb provided by early studies suggested that
malnourishment would rise by roughly 1% for each 2-2.5% rise in cereal
prices (Rosenzweig, 1993). These and subsequent analyses often make
untested assumptions about the ability of poor tropical nations to maintain
economic growth in the face of declining agricultural productivity. For
example, many African countries rely on agriculture for half or more of
all economic activity, and losses in productivity could dampen purchasing
power. Conversely, where price rises are greater than yield losses, house-
holds dependent on agricultural income could see net gains in food security.
In general, rural and urban workers with little or no landholdings are the
most vulnerable to price shocks. A new generation of models that explicitly
account for income sources among poor populations is emerging but yet to
provide robust insights. Also important could be climate-induced changes
in the incidence of diarrheal and other diseases, which inhibit food security
by reducing utilization of nutrients in food.
