Sectoral Impacts The following presents a brief overview of the most recent findings on impacts within a selection of sectors. Neither the selection of sectors nor of literature cited claims to be exhaustive. Furthermore, the comparability between studies within sectors or across sectors is complicated by differences in underlying emission scenarios and associated temperatures. Where possible, attempts have been made to relate degrees of warming to preindustrial levels. Temperature increases relative to preindustrial levels have been calculated based on the Climate Research Unit Temperature Data13 (Jones et al. 2012). In light of the knowledge gaps with respect to future effects of climate change, there are two international research projects that were recently initiated to quantify impacts within a sector and across sectors at different levels of global warming, including high-end scenarios. First, the Agriculture Model Intercomparison and Improvement Project AgMIP (launched in October 2010) is bringing together a large number of biophysical and agro-economic modelling groups explicitly covering regional to global scales to compare their results and improve their models with regard to observations (Rötter, Carter, Olesen, and Porter 2011). Second, the first Inter-Sectoral Model Intercomparison Project (ISI-MIP) was launched in December 2011 with a fast-track phase designed to provide a synthesis of cross-sectoral global impact projections at different levels of global warming (Schiermeier 2012). Both projects will profit from the new RCPs where the highest reaches about 5°C of global warming.
Agriculture The overall conclusions of IPCC AR4 concerning food production and agriculture included the following: • Crop productivity is projected to increase slightly at mid- to high latitudes for local mean temperature increases of up to 1 to 3°C depending on the crop, and then decrease beyond that in some regions (medium confidence) {WGII 5.4, SPM}.
• At lower latitudes, especially in seasonally dry and tropical regions, crop productivity is projected to decrease for even small local temperature increases (1 to 2°C) which would increase the risk of hunger (medium confidence) {WGII 5.4, SPM}. • Globally, the potential for food production is projected to increase with increases in local average temperature over a range of 1 to 3°C, but above this it is projected to decrease (medium confidence) {WGII 5.4, 5.5, SPM}. These findings clearly indicate a growing risk for low-latitude regions at quite low levels of temperature increase and a growing risk for systemic global problems above a warming of a few degrees Celsius. While a comprehensive review of literature is forthcoming in the IPCC AR5, the snapshot overview of recent scientific literature provided here illustrates that the concerns identified in the AR4 are confirmed by recent literature and in important cases extended. In particular, impacts of extreme heat waves deserve mention here for observed agricultural impacts (see also Chapter 2). This chapter will focus on the latest findings regarding possible limits and risks to large-scale agriculture production because of climate change, summarizing recent studies relevant to this risk assessment, including at high levels of global warming approaching 4°C. In particular, it will deliberately highlight important
13 (http://www.cru.uea.ac.uk/cru/data/temperature/ – October 17, 2012.
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