There is some evidence that climate change is already having a measurable affect on the quality and quantity of food produced globally. But this is small when compared with the significant increase in global food production that has been achieved over the past few decades. Isolating the influence of climatic change from all the other trends is difficult, but one recent Stanford University study found that increases in global production of maize and wheat since 1980 would have been about 5% higher were it not for climate change.
All else being equal, rising carbon dioxide concentrations – the main driver of climate change – could increase production of some crops, such as rice, soybean and wheat. However, the changing climate would affect the length and quality of the growing season and farmers could experience increasing damage to their crops, caused by a rising intensity of droughts, flooding or fires.
The latest IPCC report predicted improving conditions for food production in the mid to high latitudes over the next few decades, including in the northern USA, Canada, northern Europe and Russia. Conversely, parts of the subtropics, such as the Mediterranean region and parts of Australia, and the low latitudes, could experience declining conditions. For example, across Africa, yields from rain-fed agriculture could decline by as much as 50% by 2020. Beyond this, if global temperatures rise by more than about 1–3°C, declining conditions could be experienced over a much larger area.
The future course of global food production will depend on how well societies can adapt to such climatic changes, as well as the influence of other pressures, such as the competition for land from biofuel production. The IPCC concluded that in the poorer, low-latitude countries, climate change could seriously challenge the capacity to adapt for a warming of more than 3°C. The richer, higher latitude countries are likely to have a greater capacity to adapt and exploit changing climatic conditions.
But we can't ignore the potential for "surprises" down the line. There are many uncertainties in such predictions. The world has not seen such changes in climate for millennia, and so it is impossible to know how our agricultural systems will react in the real world. For example, the complex interlinkages with the impacts of climate change on pests, diseases and pollinators, like bees, are largely unknown. Also, climate models have difficulty in accurately predicting the detailed local environmental changes that are important for food production, particularly weather extremes.
A looming vulnerability is the world's fisheries, which provide an important source of protein for at least half the world's population. Fisheries are already stressed by overexploitation and pollution. Warming surface waters in the oceans, rivers and lakes, as well as sea level rise and melting ice, will adversely affect many fish species. Some marine fish species are already adapting by migrating to the high latitudes, but others, such as Arctic and freshwater species, have nowhere to go. The absorption of carbon dioxide emissions by the oceans also has a direct impact on marine ecosystems through ocean acidification. More
