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Food production

Climate change can influence regional famines because droughts and other extreme climate conditions have a direct influence on food crops and also by changing the ecology of plant pathogens ( Patz et al., 2005 ).

There are likely to be major effects of climate change on agricultural production and fisheries. This can be both positive and negative depending on the direct effects of temperature, precipitation, CO 2 , extreme climate variations, and sea-level rise. Indirect effects would have to do with changes in soil quality, incidence of plant diseases and weed and insect populations. Food spoilage will increase with more heat and humidity. Persistent drought has already reduced food production in Africa. There could be reduction in nutritional quality due to a reduction in the amount of nitrogen crops incorporate when CO 2 levels increase.

Malnutrition will be increased due to drought, particularly poorer countries. Increasing fuel costs also increase the cost of food, as we are already seeing in 2011. Again, this incremental cost rise affects those who already spend a large portion of their income on food and can contribute to malnutrition. About one-third, or 1.7 billion, of all people live in water-stressed countries and this is anticipated to increase to five billion by 2025. Frequency of diarrhea and other diseases like conjunctivitis that are associated with poor hygiene and a breakdown in sanitation may increase.

bar chart of projection for future EHW-like summers in Chicago
Projection for Future EHW-like Summers in Chicago . The average number of summers per decade with mortality rates projected to equal those of the Chicago analog to the European Heat Wave of 2003. Values shown are the average of three climate models for higher (orange) and lower (yellow) emission scenarios for each decade from 1980 to 2090 Source: Hellmann et al., 2007 .

Various studies suggest that increases in population at risk from malnutrition will increase from 40-300 million people over the current 640 million by 2060 ( Rosenzweig, Parry, Fischer&Frohberg, 1993 ). A more recent study said that today 34% of the population is at risk and by 2050 this value would grow to 64-72%. Climate change is associated with decreased pH (acidification) of oceans due to higher CO 2 levels. Over the past 200 years ocean pH has been reduced by 0.1 units and the IPCC predicts a drop of 0.14 to 0.35 units by 2100. This may affect shell-forming organisms and the species that depend on them. There could be a reduction in plankton due to the North Atlantic Gulf Stream ( Pauly&Alder, 2005 ). With already overexploited fish populations, it will be harder for them to recover.

Natural disasters like floods, droughts, wildfires, tsunamis, and extreme storms have resulted in millions of deaths over the past 25 years and negatively affected the lives of many more. Survivors may experience increased rates of mental health disorders such as post-traumatic stress disorder    . Wildfires reduce air quality, increasing particulate matter that provokes cardiac and respiratory problems. Sea level rise will increase flooding and coastal erosion. Indirect effects of rising sea levels include the infiltration of salt water and could interfere with stormwater drainage and sewage disposal. This could force coastal communities to migrate and create refugees with health burdens such as overcrowding, homelessness, and competition for resources. Air pollution is likely to be worse with climate change. It can also lead to mobilization of dangerous chemicals from storage or remobilize chemicals that are already in the environment.

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Source:  OpenStax, Sustainability: a comprehensive foundation. OpenStax CNX. Nov 11, 2013 Download for free at http://legacy.cnx.org/content/col11325/1.43
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