Sea level rise
Sea level rise can be described and projected in terms of or .
Increasing temperatures result in sea level rise by the thermal expansion of water and through the addition of water to the oceans from the melting of ice sheets. There is considerable uncertainty about the rate of future ice sheet melt and its contribution to sea level rise. The IPCC AR4 range of sea level rise excluded "future rapid dynamical changes in ice flow" but stated that "larger rises cannot be excluded but understanding of these effects is too limited to assess their likelihood". Some alternative analyses suggest that a rise in sea level, including ice sheet melt, exceeding 1 m by 2100 cannot be completely ruled out.
- The UKCP09 Marine & coastal projections report includes discussion of what determines sea level in Section 3.1 and describes the approach adopted in UKCP09 in Section 3.2.
- Key findings about projections of sea level change are summarised in the UKCP09 Briefing report.
- More details about the projections of absolute changes in sea level around the UK can be found in Section 3.3 of the UKCP09 Marine & coastal projections report, including tables, maps and plume plots.
- Key findings about projections of relative sea level change are available for each UK capital city and are summarised in the UKCP09 Briefing report.
- More details about the projections of relative changes in sea level around the UK can be found in Section 3.5 of the UKCP09 Marine & coastal projections report, including a table, map and plume plots.
- Some worked examples were developed prior to the launch of UKCP09 that used dummy outputs to examine how the UKCP09 Marine & coastal projections might be used. The worked examples should not be interpreted as a best practice method for using UKCP09, but as one way of using the outputs.
UKCP09 also provides a High++ scenario, which includes possible additional contributions to sea level rise from accelerated ice sheet dynamics. These effects are not fully accounted for in the IPCC AR4 ranges. The upper end of the High ++ scenario range provides a plausible but highly uncertain and very unlikely scenario for sea level rise. The use of such a scenario is for worst case and long term contingency planning rather than day-to-day investment decision making.
- For an overview of the High++ scenario, go to Section 6.2 of the UKCP09 Briefing report, with more detail provided in Section 1.3 of the UKCP09 Marine & coastal report.
Find out more
- IPCC Fourth Assessment Report, Working Group 1 report The Physical Science Basis , Chapter 10
- RealClimate article on sea level projections
- New Scientist article on the state of sea level science