A global assessment of the effects of climate policy on the impacts of climate change

The global-scale impacts of climate change on water resources and flooding under new climate and socio-economic scenarios

“…The difference between RCP8.5 and RCP2.6 includes not only different radiative forcings, but also different aerosol emissions. Taken together, these differences have the result that climate policy as assessed in Arnell et al (2013) has little effect on water resource scarcity in south and east Asia, but a large effect on exposure to increased flooding in east Asia, whilst in the assessment here the difference between RCP8.5 and RCP2.6 is large in most models in terms of water resources scarcity in south and east Asia, and generally small in terms of flood frequency in east Asia. Another comparison concluded that exposure to increased water resources scarcity was 8-17 % less with a 2°C pathway than under a 4°C pathway ) -slightly less than found here -and again the differences can largely be attributed to the use of different climate models.…”

“…The ranges are not substantially different, and the ranges in impacts at the regional scale are also similar, suggesting that the CMIP5 climate model set does not substantially reduce the range in projected impacts of climate change (as noted for temperature and precipitation by Knutti and Sedláĉek 2013). Arnell et al (2013) compared global-scale impacts under A1b and A1FI 'business-as-usual' emissions policies with impacts under a series of different emissions policy pathways. Their lowest emissions policy pathway produces similar changes in global mean temperature to RCP2.6, and avoids between 5 % and 8 % of the impacts in 2050 on exposure to increased water scarcity relative to A1b (varying with climate model pattern), and around 30-50 % of impacts on exposure to increased river flood risk.…”

“…A different ensemble of climate models was used in the two assessments, with different spatial patterns of climate change. The global temperature difference between RCP8.5 and RCP2.6 varies between climate models (from 0.4 to 0.9°C in 2050), but in Arnell et al (2013) the temperature difference was constant across all models (0.48°C). The difference between RCP8.5 and RCP2.6 includes not only different radiative forcings, but also different aerosol emissions.…”

Global megatrends and their implications for environmental assessment practice

“…Equally it is acknowledged that current policy will do little to prevent the extent of climate change that humanity is already locked-in to through ongoing GHG emissions -it can only affect the degree of change (Arnell et al, 2013). The implications of climate change overlap with other megatrends, and are largely recognised as exacerbating existing stressors on natural systems and existing challenges to social development.…”

Emulating global climate change impacts on crop yields

“…A robust and coherent assessment of the climatic impact on future crop-yields is essential to inform policy makers. Quantification of the reduction of climate change impacts in different sectors by moving from a no-mitigation approach to several alternative mitigation scenarios was the major focus of Warren et al (2013) and further evaluation of uncertainty associated with impact reduction in Arnell et al (2013). These studies concluded that urgent global measures can prevent the larger impacts of climate change that are otherwise projected to occur by mid-century.…”