Food production is intimately linked to the climate. Increased irrigation demands and prolonged droughts are associated with a warmer and less stable climate, and will increase the demand for fresh water. However, fresh water will become less accessible as glacial sources are reduced. Heat stress on crops and livestock is another major and often overlooked factor. Areas of the world specialized in cultivating specific crops may become either unsuitable for those crops or, at least less efficient, especially in areas where localized temperature increases are greater than the global average. Continued acidification of oceans due to absorption of CO2 from the atmosphere will affect marine health. The IPCC’s fifth assessment examined a wide range of regions and crops and found, with high confidence, that the negative impacts of climate change have been more common than positive impacts.
Projected surface temperature changes for early and late 21st century, relative to the period from 1980-1999. AOGCM multi-model average for upper-limit projections (Source:IPCC).
The IPCC projects with very high confidence that climate change will also increase risks from severe weather, particularly for urban populations. These include risks from storms, extreme precipitation, landslides, inland and coastal flooding, droughts and water scarcity. Risks are further increased for those lacking essential infrastructure.
Sea level rise is another major concern. Even a 0.7m sea level rise, the value predicted for the end of the century, could have drastic implications. It has been argued that by 2050, 26 major US cities will face an emerging flooding crisis and the IPCC reports high confidence projections for increased risks from storm surges. Storm surge could cost in the order of trillions by 2100. Many developing countries are more vulnerable and less able to respond to the effects of sea level rise, which, like the effects on agriculture, could add to overall geopolitical instability.
Compared to other regions, Asian countries exhibit the highest population exposed to river flooding; however, developed regions, particularly Miami, New York, New Orleans, Osaka-Kobe, Tokyo, and Amsterdam, are among the most exposed to flooding interms of assets.
Lastly, long-term prospects for sea level rise become much worse when looking beyond the end of the century. Even if the world succeeds in stabilizing global warming to the 2°C targeted by current climate negotiations, sea level rise could continue well beyond the 0.7m value predicted for the end of the century. Complex feedback processes between the world’s oceans, the climate, and the ice sheets themselves could facilitate continued melting and ultimately lead to rises as great as 6m.