Sea level rise

The headlines on sea level rise were generated from work from a variety of sources. These include the Intergovernmental Panel on Climate Change Working Group 2 report, Impacts, adaptation and vulnerability, 2007, research at the Met Office Hadley Centre and research done by the University of Southampton, Centre for Coastal Processes, Engineering and Management, School of Civil Engineering and Environment, which is part of the Tyndall Centre, and the Potsdam Institute for Climate Impacts Research.

The Met Office Hadley Centre has conducted a number of research studies looking at sea level rise in the UK and Europe. This includes work done as part of the TE2100 project which looked at sea level rise and the resilience of the Thames barrier.

In addition the IPCC WG2 report has collated research about the impacts sea level rise.

Finally, specific research was done by Prof. Robert Nicholls and Dr Sally Brown at Southampton University and Dr Jochen Hinkel at Potsdam Institute for Climate Impacts Research, looking at the affect on human populations of sea level rise.  A description of this research is given below.

Headline results for the number of additional people flooded due to extreme sea levels under a 4 degree rise in temperature and the A1B socio-economic scenario.

Dr Sally Brown1, Prof Robert J Nicholls1, Dr Jason Lowe2 and Dr Jochen Hinkel3

1. School of Civil Engineering and the Environment, University of Southampton, UK
2. Met Office Hadley Centre, Reading Unit, UK
3. Potsdam Institute for Climate Impact Research, Germany

• These results are based on QUEST-GSI research and will be presented at the 4 degrees and beyond conference on 28 -  30th September. The extended abstract for this is attached (Brown et al., 2009).
• Sea-level data is from the A1B ensemble mean MAGICC scenario. Prescribed datasets have been made based on 0.5°C-4.0°C increase in 2050 at 0.5°C increments. The number of people additionally flooded due to storm surges is modelled using DIVA (McFadden et al. 2007; Vafeidis et al. 2008) which combines sea-level and socio-economic scenarios. See methods of Brown et al. (2009) for more info.
• Data is reported in GVA regions. Example of regions and map below (sample only, this does not represent the figures below).

Our headline results (in various time periods) are:

• Rising temperatures cause global sea-level rise due to thermal expansion of seawater and the melting of land-based ice, threatening coastal populations with increased flooding and submergence among other impacts.
• Without further coastal adaptation, under a 4°C rise (translating into a 0.48m sea-level rise) in 2050, an additional 130 million people per year would be expected to be flooded due to extreme sea levels. Three quarters of the people are anticipated to live in Asia.
• Without further coastal adaptation, under a 4°C rise (translating into a 0.53m sea-level rise) in 2075, an additional 150 million people per year would be expected to be flooded due to extreme sea levels. Three quarters of the people are anticipated to live in Asia.
• Without further coastal adaptation, under a 4°C rise (translating into a 0.59m sea-level rise) in 2100, an additional 145 million people per year would be expected to be flooded due to extreme sea levels . Three quarters of the people are anticipated to live in Asia.
• For all timesteps, small islands regions have the highest relative increase in flooding without adaptation, compared to the base climate.
• However, economic analysis suggests that adaptation would be widespread in response to these changes.
• As an example, building sea dikes can decrease those potentially flooded to less than 1 million additional people per year, at annual costs of US$27 to US$35 billion. (Note: Costs are in US dollars are reported at 1995 values).
  

See the table below for further details behind the headline results.

Table 1: Additional number of people flooded as a result of surges due to sea-level rise at 4°C, using the A1B scenario.

1. The fall in the number of people from 2075 to 2100 reflects the socio-economic scenario under which global populations decline. In the regional effect is apparent from 2050 onwards as population peaks in 2050.
   

References:

• Brown, S. et al. (2009). Sea level response and impacts of a 1°C to 7°C prescribed temperature rise by 2100. 4 degrees and beyond. International climate conference, Oxford, UK. September 2009. View research
• Gregory JM, Huybrechts P (2006) Ice-sheet contributions to future sea- level change. Phil Trans Royal Soc A  364:1709-1731. View research
• Ridley J,  Gregory JM, Huybrechts P, Lowe J, (in Press) Thresholds for irreversible decline of the Greenland ice sheet, Clim. Dyn. doi 10.1007/s00382-009-0646-0 View research (registration required)
• Lowe, J.A., and J.M. Gregory, 2005: The effects of climate change on storm surges around the United Kingdom. Philos. T. Roy. Soc. A, 363, 1313-1328. View research
• McFadden, L. et al. (2007) A methodology for modelling coastal space for global assessment. Journal of Coastal Research, 23, 911-920.
• Ridley J,  Gregory JM, Huybrechts P, Lowe J, (in Press) Thresholds for irreversible decline of the Greenland ice sheet, Clim. Dyn. doi 10.1007/s00382-009-0646-0 View research (registration required)
• Nicholls, R.J., and R.J.T. Klein, 2005: Climate change and coastal management on Europe’s coast.  Managing European Coasts: Past, Present and Future, J.E. Vermaat, L. Vouwer, K. Turner and W. Salomons, Eds., Springer, Environmental Science Monograph Serices. 199-226. View research (registration required)
• Vafeidis, A.T. et al. (2008) A new global coastal database for impact and vulnerability analysis to sea-level rise. Journal of Coastal Research, 24, 917-924.

Related links

Sea level response and impacts of a 1°C to 7°C prescribed temperature rise by 2100, PDF 894.58 KB