Assessing climate change impacts, sea level rise and storm surge risk in port cities: A case study on Copenhagen

Abstract

This study illustrates a methodology to assess the economic impacts of climate change at a city scale and benefits of adaptation, taking the case of sea level rise and storm surge risk in the city of Copenhagen, capital of Denmark. The approach is a simplified catastrophe risk assessment, to calculate the direct costs of storm surges under scenarios of sea level rise, coupled to an economic input-output (IO) model. The output is a risk assessment of the direct and indirect economic impacts of storm surge under climate change, including, for example, production and job losses and reconstruction duration, and the benefits of investment in upgraded sea defences. The simplified catastrophe risk assessment entails a statistical analysis of storm surge characteristics, geographical-information analysis of population and asset exposure combined with aggregated vulnerability information. For the city of Copenhagen, it is found that in absence of adaptation, sea level rise would significantly increase flood risks. Results call for the introduction of adaptation in long-term urban planning, as one part of a comprehensive strategy to manage the implications of climate change in the city. Mitigation policies can also aid adaptation by limiting the pace of future sea level rise.

Storm surges in the Western Baltic Sea: the present and a possible future

“…Changes in the sea level on the global and local scale are one of the emerging topics in present climate research (Munk 2002;Church et al 2008), as a large number of coastal mega cities, populations and regions will be threatened by sea level rises in the future (Woodworth 2006;IPCC 2007;Hallegatte et al 2010). Much of the work is done on the assessment, hindcasting and projection of mean sea level, which can be found through tide gauges (Hupfer et al 2003;Woodworth and Blackman 2004;Vilibic and Sepic 2010;Haigh et al 2010a), satellite altimetry (Beckley et al 2007;Cazenave et al 2009) or with numerical models (Flather et al 1998;Gregory et al 2001;Church et al 2004;Landerer et al 2007).…”

“…Sea level extremes have also gained attention recently as they are directly responsible for coastal hazards and floods, and property damage. In addition to these dangers, there are also some serious concerns about the financial impact of changes in weather extremes and their resulting losses (West et al 2001;Tol et al 2008;Munich Re 2008;Hallegatte et al 2010).…”

Simplified method for scenario-based risk assessment adaptation planning in the coastal zone

“…The area under the curve is the expected value or average of the annual damages for the period for which the flood frequency curve is valid. Hallegatte et al (2011) uses a similar methodology to estimate mean annual flood losses in Copenhagen. These curves change over time as the climate changes.…”

The economics of climate change impacts and policy benefits at city scale: a conceptual framework

“…In the context of the OECD work on cities and climate change (Hanson et al 2011;Hallegatte et al 2011), a number of the impact areas laid out in Table 1 are included through the use of monetary or other quantitative metrics. In Table 1, those impacts valued in monetary terms are marked with a (V); these include mostly direct and indirect market impacts.…”

“…5 For a discussion of these policy issues, see, e.g.,Hansen (2007) andOppenheimer et al (2007). Also as part of this OECD work stream, see discussion of these issues in a global port cities flood exposure assessment byHanson et al (2011) and a case study on Copenhagen inHallegatte et al (2011).…”