Will Agriculture Be Effected By Climate Change Environmental Sciences
In a recent paper published in The Lancet it was proclaimed that "climate change is the biggest global health threat in the 21st century" (Costello et al.
There have been a number of wide ranging hypotheses and models produced attempting to predict future changes in the climate but due to its non-specific nature these predictions often conflict with each other thus giving an inaccurate portrayal of all climate models.
Nonetheless it seems that the general opinion is that climate change is occurring although to what degree is still unclear.
Global warming will have wide ranging effects on a number of different global health issues but I am going to look primarily at impacts on food and water availability as well as potential consequences of related matters such as sanitation which may be compromised if there are shortages of clean water and food.
A basic necessity of good health is adequate nutrition and there are widespread problems in areas where malnutrition is common.
It is estimated that the deaths of 3.5 million mothers and young children are caused each year due to malnutrition in areas affected by famine (Black et al.
Scientists predict that by 2100 50% of the world's population will face crippling food shortages due to the effects of climate change (Costello et al.
2009) and due to the nature of global warming it will primarily affect areas where food shortages are already a problem such as the Sahalan belt of Africa (Figure 1 (Nellmann 2009)) thus exacerbating the problems in these areas as well as affecting areas where there are currently no problems such as southern USA.
Figure 1- A world map showing the potential changes in agricultural productivity due to climate change in 2080
Aid to these areas will also be limited by the fact that global food production will fall so there will be no excess food to send to these famished areas and potential economic crises due to the global food shortage will mean developed countries will be unlikely to be donating large sums of economic aid.
This will be particularly problematic to small subsistence farmers which are so typical of resource poor countries who will be in desperate need of aid to access the technology they will need to produce food under much more difficult conditions (Morton 2007).
There are several factors that will contribute to a decline in food production.
An increase in sea levels through the melting of polar ice caps will lead to an increased risk of coastal flooding.
This will result in salinisation of land making it very difficult to grow food in these areas.
It is also predicted that there is a 90% chance that by 2100 the coolest recorded temperature in growing seasons will be higher then the highest recorded values between 1900 and 2006 potentially leading to vast food shortages associated with extremely high temperatures (Battisti et al.
Global warming is also predicted to increase the number of areas susceptible to drought meaning the actual surface area of land available to grow food to support populations will dramatically decrease as agricultural areas effectively move away from the equator as can be seen in Figure 1.
Much of the land that will open up for agriculture for example in Siberia will be unsuitable for large scale agriculture of the sort that will be lost nearer the equator due to a warmer climate as well as the problems associated with effective infrastructure in these areas to transport the food globally from what are currently extremely isolated regions (Sheeran 2008).
Predictions about potential implications on future water availability are notoriously inaccurate however the general prediction shared by the majority of climate scientists is that rainfall will become less frequent and heavier.
This will have many implications on many different aspects of global health.
The length of drought periods are likely to increase in many areas and this will mean that more and more people will be living under water scarcity (less than 1000 m3 of runoff per person per year) with the UN World Water Development Report predicting that by 2020 up to 250 million people in Africa alone could be living under water scarcity (Bullock et al.
Ironically the places predicted to experience the greatest water shortages seem to be the areas with the fastest growing populations such as the large cities if Latin America like Mexico City (Romero Lankao 2007).
This will mean more and more people will be relying on unclean water sources leading to increases in the incidence of water borne diseases such as cholera and Dengue fever (McMichael et al.
Increasing sea temperatures will mean that monsoon events will become much more intense providing large amounts of water over a short period of time.
However resource poor countries simply don't have the technology to store all of this water effectively and keep it clean throughout the extended drought season.
This will then result in diminished reserves of reliable freshwater which will force more people to attempt to store water in often unsanitary conditions for the long drought seasons leading to further spread of disease.
Retreating glaciers will also have large implications on water supplies in many areas where meltwater streams provide one sixth of the world's population with fresh water (Costello et al.
Global warming will mean that as glaciers retreat, more meltwater will be produced leading to greater discharge from the meltwater streams.
This was one of the reasons to blame for the Bihar flood of 2008 due to the Kosi River changing its course due to increased discharge costing $6.5 billion.
The increase in meltwater discharge will only be temporary as this will then be followed by a drastic fall in meltwater as the glacier retreats it will simply have less water to give out meaning that many major rivers which receive much of their supply from glacial meltwater will have significantly reduced discharge (Bates et al.
Large parts of Southeast Asia will then be affected by contraction of Himalayan glaciers and with international tensions already high between governments in this region, the potential conflict that could erupt over water availability could well have disastrous consequences.
Predictions of global warming paint a dark picture of the potential ecological disaster that could result from just a few degrees of warming.
The impact on freshwater supplies alone will have a massive knock on effect on food availability and the spread of disease as well as increasing international tensions over water supplies.
Global food shortages are also likely to be exacerbated with a rapid increase in global temperatures once again potentially causing heightened international tensions and widespread malnutrition leading to a potential global health disaster.