European drought regimes under mitigated and unmitigated climate change: application of the Community Integrated Assessment System (CIAS)

Abstract

Climate change is expected to cause significant changes in the future distribution of precipitation, as well as in the frequency and intensity of high and low rainfall events across the world. In particular, there is an expectation of drying in southern Europe and wetting in northern Europe, with some regions such as southern UK experiencing drier summers and wetter winters. In this study, a community integrated assessment system (CIAS) is used to project the impacts of climate change associated with various emissions scenarios and in particular to demonstrate the extent to which climate mitigation policy might reduce the projected changes in drought regime for Europe under climate change scenarios over the 21st century. Components of CIAS include a simple climate model, MAGICC, and a spatial climate scenario generator, ClimGen, tuned to emulate 3 global general circulation model behaviours and climate change patterns. In baseline (no mitigation policy) cases, very large increases in drought are projected for southern Europe. However, stringent mitigation policy, in which CO 2 concentrations stabilize at 450 or 400 ppm, produces very large reductions in both drought frequency and in total months of drought which would otherwise be experienced during 2050 to 2099, regardless of the global circulation model used to project the patterns of climate change across Europe. The study also illustrates a possible range of future drought scenarios which adaptation planners across Europe need to consider. ) driven by 2 alternative GCMs. Blenkinsop & Fowler (2007a,b) and Frei et al. (2006) projected future changes in drought characteristics based on the SRES A2 emissions scenario only (Nakicenovich & Swart 2000) whilst Beniston et al. (2007) used A2 and B2 SRES scenarios. Leh ner et al. (2006) simulated future European drought using a model named WaterGAP driven by the inputs of 2 alternative GCM patterns from HadCM3 and ECHAM4, considering 2 no-climate policy baselines including IS92a in which CO 2 concentrations in crease by 1% annually (IPCC 1994). Ensemble-based probabilistic projections exist for changes in European extreme precipitation (Palmer & Ralsanen 2002) for the period 2060-2080, again for IS92a, and for daily precipitation and hydrology in the UK (New et al. 2007) for doubled CO 2 concentrations. Re cent global, but regionally specific, studies have improved on these earlier studies by using a wider range of GCMs (Sheffield & Wood 2008; Hira ba yashi et al. 2008, Planton et al. 2008) but focus on 1 to 3 emissions scenarios only. None of these studies examine the implications of higher emissions of the SRES A1 fossil intensive scenario (A1FI). The present study builds on this existing work by (1) including, for the first time, the study of scenarios which include climate policy (i.e. policy-induced reductions in emissions of greenhouse gases, commonly referred to as mitigation); (2) calculating, for the first time, the benefits of the mitigation: specifically, by quantifying the reductions in pro...

Quantifying the impact of climate change on drought regimes using the Standardised Precipitation Index

“…The findings for Spain and Portugal are consistent with the consensus reached by many other modelling studies that there will be a decline in precipitation in the Mediterranean with increased drought frequency and duration (e.g. Warren et al 2012;Blenkinsop and Fowler 2007).…”

“…As the study focuses on the first half of the 21 st century there was little variability seen between results generated using the A1FI and 450ppm scenarios. As such, the implementation of a stringent mitigation policy is projected to have limited effect on worsening drought conditions from 2003-2050 compared to the A1FI scenario, whilst it should be noted that it has been shown that mitigation would greatly reduce changes in drought regime in the second half of the 21 st century, at least in Europe (Warren et al 2012) . Instead, much of the uncertainty in future projections of drought events, including the direction of change, was linked to the GCM used, consistent with Goodess et al, (2003) who reports that for the early 21 st century inter-model variability tends to be greater than inter-scenario variability.…”

“…The results are interpolated using the ClimGen 'gamma-method' which expresses the precipitation changes seen in the GCM pattern as a fractional change from present day precipitation, and also considers interannual variability independently of mean precipitation changes. The observed inter-annual variability is modified according to changes in the shape parameter of the gamma distribution, which provides a measure of skewness of the distribution, derived from the selected GCM simulation (Warren et al 2012). …”

“…A common approach is to use emission scenarios, such as those from the IPCC SRES, as proxies for actual mitigation scenarios. One exception is that of Warren et al, (2012) who investigated changing drought regimes in Europe, including for the first time scenarios of policy-induced mitigation options. This development is particularly beneficial if connections are to be made between the physical characteristics of drought and economic and social impacts, and the economic effectiveness of climate policies to mitigate such impacts.…”

“…Evidence suggests that drought events have been increasing in frequency and intensity in some regions over the latter half of the 20th century in response to global climate change (Zhang et al 2007;Lynch et al 2008;IPCC 2012). Projections also suggest that drought is likely to be further exacerbated in certain regions under future climate change, including Southern Europe and the Mediterranean, Central Europe, central North America, Central America and Mexico, northeast Brazil and Southern Africa (Sheffield and Wood 2008;Warren et al 2012;IPCC 2012).…”