As noted previously on planet doom?, agriculture is the basis of our civilization and climate change, along with other human mismanagement of our natural resources threatens to erode the very foundations of society. Recent events augur the possibility of widespread starvation as an emergent threat for the future.
Many of the issues at hand center around the soil. Not all of these are directly related to climate change, though. As a worldwide average, agricultural land loses about 1 mm of soil a year, which takes about 10 years to replace. Furthermore, this reduces the ability of the land to support crops, meaning more (petroleum-based) fertilizers need to be applied to generate the same yield. All told, some 30% of the world's arable land has been abandoned since the 1960s (e.g. Suzuki, The Sacred Balance) because the soil has been depleted away.
The application of nitrogen-based fertilizers in agriculture also threatens the broader environment. These fertilizers, invented in the early-20th century, lifted limits on food production and allowed the world's population to soar (undoubtedly part of our current problem...). But it also disrupted the natural cycles of nitrogen in the environment. Agricultural run-off and combustion of fossil fuels all release nitrogen, enhancing vegetation, including invasive weeds and consequently altering local ecosystems. Runoff of nitrates also increases algae, which can kill coral reefs and form toxic algal blooms, leading to so-called 'dead zones' in the oceans.
Agricultural land is also under threat from desertification and drought. Desertification is caused in part by human activities like overgrazing, water demand and deforestation. But climate change poses a greater threat. Changing weather patterns and more frequent droughts lead to more desertification. This, in turn provides a feedback, resulting in even more climate change. Global warming could also increase the incidence of crop disease. Effects of climate change-related drought (Is it?) and the rush to produce biofuels on food production are already beginning to be felt, resulting in increasing food prices in many places.
The food supply from the oceans is also threatened by climate change and overfishing. This season's tuna catch in the Indian Ocean is its lowest in 11 years of reporting. Overfishing is a known problem, but at least somewhat reversible with informed management. The effects of climate change on fisheries may eventually become to great to manage.
These are pressing issues, and the available solutions require careful planning and forethought. Adopting no-till agricultural methods to reduce soil erosion is one step. The population is very high and growing. It will be tricky to manage fertilizer (and pesticide!) use to minimize environmental pollution while still producing enough food. Genetically modified crops or high-tech cross-breeding programs may be needed. 'Forest farming' – using the land for multiple purposes – may be a solution in some areas. A crucial step towards a solution which has been neglected for too long is managing the population to a more sustainable level. But how we do that without a devastating war, pandemic and/or mass starvation is unknown...