Page 63 - FAO-IPCC Expert meeting on climate change

Appendix 01: Speakers’ summary notes
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Extreme events, and their impacts on crops, are difficult to simulate. Climate models do not yet capture observed trends in extremes over time. Crop models have not always tested or reported the interannual variability of output yields, instead using it as an error bar on estimates of mean yields. However, this has changed in recent years. A study published in Feb 2017 confirms what is known about some of the observed effects of high temperatures on crops, and shows that models can capture some of the underlying mechanisms. More remains to be done at this process level.
IPCC AR5 chapter 7 noted that food price volatility can be triggered by extreme events, and that (non-equilibrium) economic models to capture this effect do not exist. Progress has been made since then, but much remains to be done to assess risks. Extreme events, and public and private sector responses to them, are now known to have serious knock- on effects through trade-induced cross-border amplification of climate-related food risks. These risks include food price spikes, food safety issues and interactions with conflict and migration, to name but a few. Interactions beyond food systems, e.g. energy systems (via biofuels) create the potential for food system failures, especially if there were to be
a multiple breadbasket failure. These risks has not yet been adequately characterised, and can likely only be partially quantified.
The UK Climate Change Risk Assessment 20171 highlighted a number of relevant research gaps:
• Quantify the covariate nature of risk of multiple food production failures in world regions.
• Assess the risk posed by abrupt change and climate tipping points to global food production including an
assessment of the likelihood, impact and geopolitical consequences of climate change and food insecurity.
• Characterise and quantify food system risks in supply chains, nutrition, and political instability due to extreme
weather and climate change.
Hotspots of impacts are fairly well characterised, but there is less known on when impacts are expected
Traditional projection methods ask what the range of possible impacts is for a given timeslice. Methods are now available to ask what thresholds of temperature or impact (e.g. crop yield) are important, and assess the time interval during which these are likely to be exceeded. This can be carried out for a range of scenarios and the analysis can include metrics for the sensitivity (or vulnerability) of the system studied2.
1 2
https://www.theccc.org.uk/uk-climate-change-risk-assessment-2017/ccra-chapters/international-dimensions/ http://www.nature.com/nclimate/journal/v6/n10/full/nclimate3061.html
FAO-IPCC Expert meeting on climate change, land use and food security