Sea level rise increases the frequency and severity of coastal flooding and rates of coastal erosion. Sea level rise will continue far beyond the 21st century, even if global temperature increase is limited to 2°C above pre-industrial levels. This POSTnote sets out the causes and likely future levels of sea level rise and its implications. It updates POSTnote 363 on Sea Level Rise, published in September 2010.Jump to full report >>
Global mean sea level (GMSL) has risen 20 cm since 1900, at an average rate of 1.5mm per year during 1901-1990. During 1993-2014 it rose on average 3.2 mm per year. The rate of sea level rise during the 20th century was faster than at any point since reaching near modern-day levels around 3,000 years ago. Higher sea levels increase the likelihood of coastal flooding and speed up coastal erosion, which poses problems for UK coastal communities, businesses, infrastructure and habitats. Current UK annual damages from coastal flooding are estimated at £540 million per year, and will almost certainly increase with future sea level rise.
Human greenhouse gas (GHG) emissions have increased global surface temperatures, which causes sea level rise in two main ways:
From 1993 to 2014 GMSL rose 6.4 cm. 40% of this rise was caused by thermal expansion, 20% by the Greenland and Antarctic ice sheets and 25% by glaciers elsewhere. Satellite observations show that the net sea level contributions from the Greenland and Antarctic ice sheets increased considerably over the past decade. Their contributions are projected to continue to increase because of climate change, but the future rate is uncertain.
Key points in this POSTnote include:
This POSTnote accompanies POSTbrief 25 - Projecting Future Sea Level Rise.
POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:
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