Wolfgang Kron

Flood risk and climate change: global and regional perspectives

Abstract A holistic perspective on changing rainfall-driven flood risk is provided for the late 20th and early 21st centuries. Economic losses from floods have greatly increased, principally driven by the expanding exposure of assets at risk. It has not been possible to attribute rain-generated peak streamflow trends to anthropogenic climate change over the past several decades. Projected increases in the frequency and intensity of heavy rainfall, based on climate models, should contribute to increases in precipitation-generated local flooding (e.g. flash flooding and urban flooding). This article assesses the literature included in the IPCC SREX report and new literature published since, and includes an assessment of changes in flood risk in seven of the regions considered in the recent IPCC SREX report—Africa, Asia, Central and South America, Europe, North America, Oceania and Polar regions. Also considering newer publications, this article is consistent with the recent IPCC SREX assessment finding that the impacts of climate change on flood characteristics are highly sensitive to the detailed nature of those changes and that presently we have only low confidence1 in numerical projections of changes in flood magnitude or frequency resulting from climate change. Editor D. Koutsoyiannis Citation Kundzewicz, Z.W., et al., 2013. Flood risk and climate change: global and regional perspectives. Hydrological Sciences Journal, 59 (1), 1–28.

Flood Risk = Hazard • Values • Vulnerability

Abstract Worldwide, flooding is probably the number one cause of losses from natural events. No region in the world is safe from being flooded. As the flood risk is a function of the flood hazard, the exposed values and their vulnerability, the increase in flood losses must be attributed to changes in each of these aspects. While flood protection measures may reduce the frequency of inundation losses, appropriate preparedness measures lessen the residual financial risk considerably. Besides public and private measures, insurance is a key factor in reducing the financial risk for individuals, enterprises, and even whole societies. In recent years, the demand for flood insurance has been growing. This is forcing the insurance industry to develop appropriate solutions. At the same time it is vital for the insurers to know the probable maximum losses they might face as the result of an extreme event.

World Map of Natural Hazards - A Global View of the Distribution and Intensity of Significant Exposures

Natural hazards are becoming increasingly significant these days. There is a need for documentation that concisely presents the type and magnitude of natural hazards as an aid to political and economic decision making.With the aim of presenting the global distribution of exposure to the most significant natural hazards as objectively as possible, Munich Res Geoscience Research Group published its first World Map of Natural Hazards in 1978. After being revised in 1988, the map was completely reworked and extensively expanded in 1998. The results of earlier work and the latest findings in scientific literature were drawn together and presented in a form that practitioners find both accessible and – bearing in mind the needs of the insurance technicians in particular – readily usable.In the production of this third edition, all the basic data were for the first time recorded, adjusted, and analysed with the aid of geographic information systems (GIS). The resulting map in DIN A0 format (841×: 1189mm) and the30-cm globe were produced exclusively with the techniques of digital cartography.A main map and four auxiliary maps present the following types of hazards together with background information:• Earthquake and vulcanism (shaking risk, Mexico-City-effect, tsunami,volcanic activity, plate tectonics).• Windstorm (tropical cyclone, extratropical storm, regional storm, tornado, hail, and lightning).• Flood (storm surge, severe rainfall).• Marine hazards (high waves, pack ice, and iceberg drift).• Effects of El Niño and climate change.In particular, hazard information has been stated, as far as possible,as numbers which can be checked and be used directly in insurance calculations.Hazard is often understood as a quantity that relates the occurrence/frequency and intensity of an event to a specific time interval and so is usually expressed in terms of a probability. Whenever possible, therefore,the hazard information on the world map has three essential components – intensity, frequency and reference period.The map comes with an accompanying brochure, which contains a description ofthe methods and scales used as well as a comprehensive catalogue of major natural catastrophes throughout the world.A considerably extended CD-ROM version of the World Map of Natural Hazardswith numerous additional functionalities is also available now.

Declining vulnerability to river floods and the global benefits of adaptation

Significance Understanding the vulnerability of societies around the world is crucial for understanding historical trends in flood risk and for producing accurate projections of fatalities and losses. We reproduced historical river flood occurrence using daily climate data for the period 1980–2010 and quantified the natural and socioeconomic contributions to flood risk trends. We show that the fatalities and losses as a share of the exposed population and gross domestic product are decreasing with rising income. We also show that there is a tendency of convergence in vulnerability levels between low- and high-income countries. Projections based on a wide range of climate change and socioeconomic development scenarios demonstrate that amplified adaptation efforts have the potential to largely contain losses from future floods. The global impacts of river floods are substantial and rising. Effective adaptation to the increasing risks requires an in-depth understanding of the physical and socioeconomic drivers of risk. Whereas the modeling of flood hazard and exposure has improved greatly, compelling evidence on spatiotemporal patterns in vulnerability of societies around the world is still lacking. Due to this knowledge gap, the effects of vulnerability on global flood risk are not fully understood, and future projections of fatalities and losses available today are based on simplistic assumptions or do not include vulnerability. We show for the first time (to our knowledge) that trends and fluctuations in vulnerability to river floods around the world can be estimated by dynamic high-resolution modeling of flood hazard and exposure. We find that rising per-capita income coincided with a global decline in vulnerability between 1980 and 2010, which is reflected in decreasing mortality and losses as a share of the people and gross domestic product exposed to inundation. The results also demonstrate that vulnerability levels in low- and high-income countries have been converging, due to a relatively strong trend of vulnerability reduction in developing countries. Finally, we present projections of flood losses and fatalities under 100 individual scenario and model combinations, and three possible global vulnerability scenarios. The projections emphasize that materialized flood risk largely results from human behavior and that future risk increases can be largely contained using effective disaster risk reduction strategies.

Coasts: the high-risk areas of the world

No other region is more threatened by natural perils than coasts. Fierce winds, storm surges, large waves and tsunamis expend their destructive energy when they reach the coastline. Constituting, in many cases, the boundary between continental plates, coasts experience earthquakes and volcanic eruptions more frequently. The changing climate poses the threat of sea level rise. Most global trade crosses the oceans; ports are the entry and exit points of a nation’s trade. As a consequence, coasts attract people, businesses and industries. Some coastal regions rank among the top places in the world in terms of population and value accumulation. Enormous catastrophe loss potentials have been created and are increasing. Risk is the result of a natural hazard, the values at risk and their vulnerability. Living with and reducing the risk requires awareness at all levels of society and partnership between the public authorities, the people and enterprises concerned, and the financial sector. Great natural events are not avoidable, great disasters are. Catastrophes are not only products of chance but also the outcome of the interaction between political, financial, social, technical and natural circumstances. Effective safeguards are both achievable and indispensable, but they will never provide complete protection. In order to manage the risks faced by a society, we have to be aware of that.

Natural Disasters: Lessons from the Past - Concerns for the Future

AbstractSummary The statistics of natural disasters with respect to number of deaths, economic losses and insured losses are each dominated by different types of events: earthquakes and storm surges represent the deadliest threat, floods and earthquakes exert the most severe economic strains on societies, and storms are responsible for the highest insurance losses. Disasters in mountain areas are usually much smaller as their consequences are felt only locally. The number of great natural disasters has increased by a factor of 3.2 from the 1960s to the 1990s. In the same period, the economic and insured losses they generated increased by factors of 8.6 and 16.1 respectively. The main causes for this development are: the increasing concentration of people and values in areas that are exposed to unfavourable natural conditions; the increasing vulnerability of structures and goods; the — often unjustified — trust in protection systems; and changes in environmental conditions including climate change. Despite all the efforts being made to prevent disasters by structural countermeasures, the risks in mountain areas are increasing due to the growing number of tourists and the unchanged practice of using hazardous mountain sites for residential and recreational purposes.

Benefits of Early Warning from the Viewpoint of the Insurance Industry

Losses from natural disasters have increased dramatically since the sixties. Consequently, loss prevention measures are becoming increasingly important reducing as a means of minimizing the loss burden from such events, particularly in the insurance sector. At the same time, methods of forecast, prediction, early warning and alert have become more sophisticated, more viable and more reliable, at least for some types of hazard. However, the applicability of event forecasts/predictions and early warnings differs according to the type of hazard and the lead time available to carry them out. While there are many well-functioning operational warning systems for hydro-meteorological events, it is still difficult to warn of geological hazards. The success of warning systems for hydro-meteorological events has been observed particularly with respect to tropical cyclones (Hugo/South Carolina 1989), storm surges (North Sea 1995) and floods (Odra 1997). Here, modern methods of detection, observation, evaluation and communication methods, e.g. by satellite, provide a good basis for warning a threatened region of an imminent extreme event. The experience with volcanic eruption predictions is mixed. Successful evacuation (Pinatubo 1992, Rabaul 1994, Mon-tserrat 1996) does not necessarily result in lower insured losses. To anticipate the onset of an earthquake remains the biggest challenge of all. The opportunities for loss reduction on the basis of real-time early warning systems (such as shutting off energy supply and critical facilities as already implemented at some locations in California, Mexico and Taiwan) are promising but still need to be tested during severe events.