Global projections of changing risks of floods and droughts in a changing climate

Hirabayashi, Yukiko; Kanae, Shinjiro; Emori, Seita; Oki, Taikan; Kimoto, Masahide

doi:10.1623/hysj.53.4.754

Cited by 373 publications

(274 citation statements)

References 28 publications

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“…Forzieri et al (2014) project an increase in deficit volume of river flow for vast areas of Europe, except the Scandinavian countries and North Russia. Hirabayashi et al (2008) and Feyen and Dankers (2009) project a substantial increase in the number of drought days (PDY) or flow deficit volume for the period 2071-2100 in some regions, whereas in contrast, wide areas will benefit from a decrease in drought days. An increase in number of drought days in general is not in line with the modelling experiment in this study, whereas an increase in deficit volume is supported (Table 4).…”

Section: Discussionmentioning

confidence: 99%

Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

Wanders

Lanen

2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study a conceptual hydrological model was forced by downscaled and bias-corrected outcome from three general circulation models for the SRES A2 emission scenario (GCM forced models), and the WATCH Forcing Data set (reference model). The threshold level method was applied to investigate drought occurrence, duration and severity. Results for the control period show that the drought characteristics of each GCM forced model reasonably agree with the reference model for most of the climate types, suggesting that the climate models' results after post-processing produce realistic outcomes for global drought analyses. For the near future (2021-2050) and far future (2071-2100) the GCM forced models show a decrease in drought occurrence for all major climates around the world and increase of both average drought duration and deficit volume of the remaining drought events. The largest decrease in hydrological drought occurrence is expected in cold (D) climates where global warming results in a decreased length of the snow season and an increased precipitation. In the dry (B) climates the smallest decrease in drought occurrence is expected to occur, which probably will lead to even more severe water scarcity. However, in the extreme climate regions (desert and polar), the drought analysis for the control period showed that projections of hydrological drought characteristics are most uncertain. On a global scale the increase in hydrological drought duration and severity in multiple regions will lead to a higher impact of drought events, which should motivate water resource managers to timely anticipate the increased risk of more severe drought in groundwater and streamflow and to design pro-active measures.

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Section: Discussionmentioning

confidence: 99%

Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

Wanders

Lanen

2015

Nat. Hazards Earth Syst. Sci.

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“…The focus on the 100-year event enables a direct comparison with other studies (Lehner et al 2006;Hirabayashi et al 2008;Dankers and Feyen 2009). …”

Section: Flood Frequencymentioning

confidence: 99%

“…Bell et al 2007;Prudhomme et al 2003;Milly et al 2002;Lehner et al 2006;Hirabayashi et al 2008;Dankers and Feyen 2009;Dankers et al 2013). A key conclusion of such studies is that the projected effects of climate change on the flood hazard may be very substantial, but are very dependent on climate scenario.…”

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confidence: 99%

The impacts of climate change on river flood risk at the global scale

2014

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This paper presents an assessment of the implications of climate change for global river flood risk. It is based on the estimation of flood frequency relationships at a grid resolution of 0.5×0.5°, using a global hydrological model with climate scenarios derived from 21 climate models, together with projections of future population. Four indicators of the flood hazard are calculated; change in the magnitude and return period of flood peaks, flood-prone population and cropland exposed to substantial change in flood frequency, and a generalised measure of regional flood risk based on combining frequency curves with generic flood damage functions. Under one climate model, emissions and socioeconomic scenario (HadCM3 and SRES A1b), in 2050 the current 100-year flood would occur at least twice as frequently across 40 % of the globe, approximately 450 million flood-prone people and 430 thousand km 2 of flood-prone cropland would be exposed to a doubling of flood frequency, and global flood risk would increase by approximately 187 % over the risk in 2050 in the absence of climate change. There is strong regional variability (most adverse impacts would be in Asia), and considerable variability between climate models. In 2050, the range in increased exposure across 21 climate models under SRES A1b is 31-450 million people and 59 to 430 thousand km 2 of cropland, and the change in risk varies between −9 and +376 %. The paper presents impacts by region, and also presents relationships between change in global mean surface temperature and impacts on the global flood hazard. There are a number of caveats with the analysis; it is based on one global hydrological model only, the climate scenarios are constructed using pattern-scaling, and the precise impacts are sensitive to some of the assumptions in the definition and application.

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“…Dankers and Feyen (2008) and Hirabayashi et al (2008) indicated a decrease in water flow, whereas Lehner et al (2006) suggested an increase, and Arheimer et al (2012) projected very little overall change in water discharge to the Baltic Sea. Discrepancies between conclusions regarding the future can arise due to uncertainties in GCMs, downscaling methods, or hydrological models (e.g., Bosshard et al, 2013;Donnelly et al, 2014;Hall et al, 2014).…”

Section: Changes In High Flows In Swedenmentioning

confidence: 99%

Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

Arheimer

Lindström

2015

Hydrol. Earth Syst. Sci.

130

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Abstract. There is an ongoing discussion whether floods occur more frequently today than in the past, and whether they will increase in number and magnitude in the future. To explore this issue in Sweden, we merged observed time series for the past century from 69 gauging sites throughout the country (450 000 km 2 ) with high-resolution dynamic model projections of the upcoming century. The results show that the changes in annual maximum daily flows in Sweden oscillate between dry and wet periods but exhibit no significant trend over the past 100 years. Temperature was found to be the strongest climate driver of changes in river high flows, which are related primarily to snowmelt in Sweden. Annual daily high flows may decrease by on average −1 % per decade in the future, mainly due to lower peaks from snowmelt in the spring (−2 % per decade) as a result of higher temperatures and a shorter snow season. In contrast, autumn flows may increase by +3 % per decade due to more intense rainfall. This indicates a shift in floodgenerating processes in the future, with greater influence of rain-fed floods. Changes in climate may have a more significant impact on some specific rivers than on the average for the whole country. Our results suggest that the temporal pattern in future daily high flow in some catchments will shift in time, with spring floods in the northern-central part of Sweden occurring about 1 month earlier than today. High flows in the southern part of the country may become more frequent. Moreover, the current boundary between snow-driven floods in northern-central Sweden and rain-driven floods in the south may move toward higher latitudes due to less snow accumulation in the south and at low altitudes. The findings also indicate a tendency in observations toward the modeled projections for timing of daily high flows over the last 25 years. Uncertainties related to both the observed data and the complex model chain of climate impact assessments in hydrology are discussed.

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Global projections of changing risks of floods and droughts in a changing climate

Cited by 373 publications

References 28 publications

Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

The impacts of climate change on river flood risk at the global scale

Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

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