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Climate Change and Food
Climate change has many potential impacts on the production of food crops—from food scarcity and nutrient deficiency to possible increased food production because of elevated carbon dioxide (CO2) levels—all of which directly affect human health. Part of this variability in possible outcomes is from the various climate change models used to project potential impacts; each model takes into account different factors and so come out with a slightly different result. A second problem comes from the fact that projections are made based on historical data which is not necessarily helpful in accurate forecasting as changes are occurring exponentially. As such, there are many different possible impacts—both positive and negative—that may result from climate change affecting global regions in different ways.

Food Scarcity
Food scarcity is a major concern for many populations and is one of the prominent concerns with the changing climate. Currently, 1/6 of the global population are without adequate food supply. By 2050, the global population is projected to reach 9 billion requiring global food productions to increase by 50% to meet population demand. In short, food scarcity is a growing concern that, according to many researchers, is projected to worsen with climate change because of a number of factors including extreme weather events and an increase in pests and pathogens.

Rising Temperatures
As the temperature changes and weather patterns become more extreme, areas which were historically good for farmland will no longer be as amicable. The current prediction is for temperature increase and precipitation decrease for major arid and semi-arid regions (Middle East, Africa, Australia, Southwest United States, and Southern Europe). In addition, crop yields in tropical regions will be negatively affected by the projected moderate increase in temperature (1-2°C) expected to occur during the first half of the century. During the second half of the century, further warming is projected to decrease crop yields in all regions including Canada and Northern United States. Many staple crops are extremely sensitive to heat and when temperatures rise over 36°C, soybean seedlings are killed and corn pollen loses its vitality. Scientists project that an annual increase of 1°C will in turn decrease wheat, rice and corn yields by 10%.

There are, however, some positive possible aspects to climate change as well. The projected increase in temperature during the first half of the century (1-3°C) is expected to benefit crop and pasture yields in the temperate regions  .This will lead to higher winter temperatures and more frost-free days in these regions; resulting in a longer growing season, increased thermal resources and accelerated maturation. If the climate scenario results in mild and wet weather, some areas and crops will suffer, but many may benefit from this.

Drought and Flood
Extreme weather conditions continue to decrease crop yields in the form of droughts and floods. While these weather events are becoming more common, there is still uncertainty and therefore a lack of preparedness as to when and where they will take place. In extreme cases, floods destroy crops, disrupting agricultural activities and rendering workers jobless and eliminating food supply. On the opposite end of the spectrum, droughts can also wipe out crops. It is estimated that 35-50% of the world’s crops are at risk of drought. Australia has been experiencing severe, recurrent droughts for a number of years, bringing serious despair to its farmers. The country’s rates of depression and domestic violence are increasing and as of 2007, more than one hundred farmers had committed suicide as their thirsty crops slipped away. Drought is even more disastrous in the developing world, exacerbating the pre-existing poverty and fostering famine and malnutrition.

Droughts can cause farmers to rely more heavily on irrigation; this has downsides for both the individual farmers and the consumers. The equipment is expensive to install and some farmers may not have the financial ability to purchase it. The water itself must come from somewhere and if the area has been in a drought for any length of time, the rivers may be dry and the water must be transported from further distances. With 70% of “blue water” currently being used for global agriculture, any need over and above this could potentiate a water crisis. In Sub-Saharan Africa, water is used to flood rice fields to control the weed population; with the projection of less precipitation for this area, this historical method of weed control will no longer be possible. .

With more costs to the farmer, some will no longer find it financially feasible to farm. Agriculture employs the majority of the population in most low-income countries and increased costs can result in worker layoffs or pay cuts. Other farmers will respond by raising their food prices; a cost which is directly passed on to the consumer and impacts the affordability of food. Some farms do not export their goods and their function is to feed a direct family or community; without that food, people will not have enough to eat. This results in decreased production, increased food prices, and potential starvation in parts of the world.

Financial
Some research suggests that initially climate change will help developing nations because some regions will be experiencing more negative climate change effects which will result in increased demand for food leading to higher prices and increased wages. However, many of the projected climate scenarios suggest a huge financial burden. For example, the heat wave that passed through Europe in 2003 cost 13 billion euros in uninsured agriculture losses. In addition, during El Nino weather conditions, the chance of the Australian farmer’s income falling below average increased by 75%, greatly impacting the country’s GDP. The agriculture industry in India makes up 52% of their employment and the Canadian Prairies supply 51% of Canadian agriculture; any changes in the production of food crops from these areas could have profound effects on the economy. This could negatively affect the affordability of food and the subsequent health of the population.

Pests & Pathogens
Currently, CO2 levels are 40% higher than they were in pre-industrial times. This diminishes nutritional content for both human and insect consumption. Studies have shown that when CO2 levels rise, soybean leaves are less nutritious; therefore plant-eating beetles have to eat more to get their required nutrients. In addition, soybeans are less capable of defending themselves against the predatory insects under high CO2. The CO2 diminishes the plant’s jasmonic acid production, an insect-killing poison that is excreted when the plant senses it’s being attacked. Without this protection, beetles are able to eat the soybean leaves freely, resulting in a lower crop yield. This is not a problem unique to soybeans, and many plant species’ defense mechanisms are impaired in a high CO2 environment.

Currently, pathogens take 10-16% of the global harvest and this level is likely to rise as plants are at an ever-increasing risk of exposure to pests and pathogens. Historically, cold temperatures at night and in the winter months would kill off insects, bacteria and fungi. The warmer, wetter winters are promoting fungal plant diseases like soybean rust to travel northward. Soybean rust is a vicious plant pathogen that can kill off entire fields in a matter of days, devastating farmers and costing billions in agricultural losses. Another example is the Mountain Pine Beetle epidemic in BC, Canada which killed millions of pine trees because the winters were not warm enough to slow or kill the growing beetle larvae. The increasing incidence of flooding and heavy rains also promotes the growth of various other plant pests and diseases. On the opposite end of the spectrum, drought conditions favour different kinds of pests like aphids, whiteflies and locusts.

The competitive balance between plants and pests has been relatively stable for the past century, but with the rapidly shifting climate, there is a change in this balance which often favours the more biologically diverse weeds over the monocrops most farms consist of. Currently, weeds claim about one tenth of global crop yields annually as there are about eight to ten weed species in a field competing with crops. Characteristics of weeds such as their genetic diversity, cross-breeding ability, and fast-growth rates put them at an advantage in changing climates as these characteristics allow them to adapt readily in comparison to most farm's uniform crops, and give them a biological advantage. There is also a shift in the distribution of pests as the altered climate makes areas previously uninhabitable more uninviting. Finally, with the increased CO2 levels, herbicides will lose their efficiency which in turn increases the tolerance of weeds to herbicides.

Nutrition
Another area of concern is the effect of climate change on the nutritional content of food for human consumption. Studies show that increasing atmospheric levels of CO2 have an unfavourable effect on the nutrients in plants. As the carbon concentration in the plant’s tissues increase, there is a corresponding decrease in the concentration of elements such as nitrogen, phosphorus, zinc and iodine. Of significant concern is the protein content of plants, which also decreases in relation to elevating carbon content. Irakli Loladze explains that the lack of essential nutrients in crops contributes the problem of micronutrient malnutrition in society, commonly known as “hidden hunger”; despite adequate caloric intake, the body still is not nutritionally satisfied and therefore continues to be “hungry”. This problem is aggravated by the rising cost of food, resulting in a global shift towards diets which are less expensive, but high in calories, fats, and animal products. This results in undernutrition and an increase in obesity and diet-related chronic diseases. Countries worldwide are already impacted by deficiencies in micronutrients and are seeing the effects in the health of their populations. Iron deficiency affects more than 3.5 billion people; increasing maternal mortality and hindering cognitive development in children, leading to education losses. Iodine deficiency leads to ailments like goitre, brain damage and cretinism and is a problem in at least 130 different countries. Even though these deficiencies are invisible, they have great potential to impact human health on a global scale. It must also be noted that small increases in CO2 levels can cause a CO2 fertilization effect where the growth and reproduction abilities of C3 plants such as soybeans and rice are actually enhanced by 10-20% in laboratory experiments. This does not take into account, however, the additional burden of pests, pathogens, nutrients and water affecting the crop yield.

Adaptation and Mitigation Strategies
While researchers acknowledge there are possible benefits, most agree that the negative consequences of climate change will outweigh any potential benefits and instead the shifting climate will result in more benefits to developed countries and more detriments to developing countries; exacerbating the discrepancy between wealthy and impoverished nations. By thoughtful and proactive efforts, climate change can be mitigated by addressing these issues with a multidisciplinary approach that works on a global, national and community basis that recognizes the uniqueness of each country’s situation. According to a study of East Africa’s smallholder farms, impacts of climate change on agriculture are already being seen there resulting in changes to farming practices such as intercropping, crop, soil, land, water and livestock management systems, and introduction of new technologies and seed varieties by some of the farmers. Some other suggestions such as eliminating supply chain and household food waste, encouraging diverse and vegetable-rich diets, and providing global access to foods (food aid programs) have been suggested as ways to adapt. Many researchers agree that agricultural innovation is essential to addressing the potential issues of climate change. This includes better management of soil, water-saving technology, matching crops to environments, introducing different crop varieties, crop rotations, appropriate fertilization use, and supporting community-based adaptation strategies. On a government and global level, research and investments into agricultural productivity and infrastructure must be done to get a better picture of the issues involved and the best methods to address them. Government policies and programs must provide environmentally sensitive government subsidies, educational campaigns and economic incentives as well as funds, insurance and safety nets for vulnerable populations. In addition, providing early warning systems, and accurate weather forecasts to poor or remote areas will allow for better preparation; by using and sharing the available technology, the global issue of climate change can be addressed and mitigated by the global community.