Many millions of species – plants, animals and micro-organisms – inhabit Planet Earth. But this rich biological diversity is being eroded, and species are becoming extinct at an alarming rate. This trend jeopardises the whole of mankind. Especially the decline in agrobiodiversity, which is the resource base for our food, is a severe problem.
Climate change – a threat to food security
Environmental change is one of many factors reducing the diversity of crops and livestock. Five climate change-related factors can be identified: the rise in temperatures, changes in precipitation patterns, the rise of sea levels, higher incidence of extreme weather events and the increase of greenhouse gases – especially carbon dioxide – in the atmosphere.
The rise in temperature – commonly known as global warming – is expected to be highest in the tropics and subtropics. The anticipated consequences there will be large-scale extinction of species, lower agricultural yields and a major change in cropping systems. The global water supply will also be seriously affected by climate change. In the last century, for example, subtropical regions most likely received around 3 % less precipitation and suffered more frequently from drought than in the preceding centuries.
In summary, dramatic implications are expected for agriculture and food supply, although with large regional differences. It is predicted that the 40 poorest countries, located predominantly in Africa and Latin America, may lose 10 – 20 % of their grain-growing capacity due to drought by 2080. It is also argued that many rain-fed crops in some areas are already near their maximum temperature tolerance, and their yield may fall sharply with a further temperature rise. By contrast, yield increases are expected in temperate regions. Tragically, these changes are likely to hit the world´s poorest people hardest.
Combating such changes requires a two-pronged strategy of mitigation and adaption. On the one hand all possible efforts must be made to reduce greenhouse gas emissions and to slow climate change. On the other, fast and appropriate action is needed to enhance capacity to adapt to irreversible changes in the system.
Agrobiodiversity – an indispensable part of the solution
Agricultural genetic resources are not only a victim of climate change; they are of fundamental importance for adaptation to this change. Plants and animals which have until now had no economic value but which can cope with the changing climatic situation will become more important. One question immediately arises: how much agrobiodiversity should we conserve for our future?
Attempts should be made to maximize agrobiodiversity while keeping costs as low as possible. The ex situ conservation (e.g. botanical gardens, storage of seeds in refrigerated banks) is essential but does not go nearly far enough. What is needed are conservation schemes that rely primarily on in situ concepts – the conservation and breeding of genetic resources by farmers on their farms and in their villages. Such in situ schemes enable the use and conservation of genetic resources to be closely linked. The inherent value of seemingly uneconomic crops or farming systems needs to be recognized and harnessed.
Plants, animals and ecosystems have the capacity to adjust to changes in factors such as heat, drought or salinity, and this enables us to cope with the consequences of changing environments. Adaption is a dynamic process and difficult to achieve through genetic engineering. It is best developed through classical breeding and through growing the plants in the fields where they are exposed to a wide range of ecological conditions.
Refereces: von Lossau, Anette (2011): Agrobiodiversity and climate change - A complex relationship