Intergovernmental Panel on Climate Change:
Fifth Assesment Report; Working Group One:
Chapter 13: Sea Level Change
Chapter Summary and Implications
The mission of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) Working Group One (WG1) is to fully assess the current state of scientific knowledge on past, present, and future climate. This site is designed as a critical summary and review of Chapter 13: Sea Level Change and was developed as part of a graduate course at the University of Colorado Boulder.
Written as an assessment of the current state of knowledge of past and future global sea level change, this chapter provides a comprehensive overview of decades of observation and research. It is therefore not surprising that the depth and breadth of content is daunting and difficult to digest (not to mention lengthy). This website is designed as summary of the content of Chapter 13 to allow easier access to the material for both the scientific and public communities. The author also offers brief critiques and comments on the relevance and impacts.
Purpose of Site
Key Results
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The rate of sea level rise from 1850 to present is larger than the mean rate of sea level rise during the previous two millennia (high confidence).
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From 1901 to 2010 global mean sea level rose by 0.19 [0.17 - 0.21] m (Section 13.2).
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Thermal expansion of the oceans and glacier mass loss explain about 75% of observed global sea level rise since 1970 (high confidence). From 1993 to 2010 global mean sea level rise (GMSLR) is consistent with the observed contribution from thermal expansion (1.1 [0.8-1.4] mm/yr), glacier mass loss (0.76 [0.39-1.13] mm/yr), Greenland Ice Sheet (0.33 [0.25-0.41] mm/yr), Antarctic Ice Sheet (0.27 [0.16-0.38] mm/yr), and land water storage (0.38 [0.26-0.49] mm/yr) for a total rate of 2.8 [2.3-3.4] mm/yr (Section 13.3).
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During the Last Interglaciation (129,000-116,000 BP (Before Present)) global mean sea level was at least 5 m above present (very high confidence) but did not exceed 10 m above present (high confidence). This change in sea level happened over several thousand years due to changes in orbital forcings under conditions at least 2 degrees Celsius warmer than today.
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Regional sea level will vary significantly over the next century, but the projected distribution and magnitude is uncertain.
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Changes in extreme sea level events (storm surges) are dependent on changes in the frequency and intensity of storm systems. Large scale changes in wave habit (height, direction, and speed) are difficult to predict, but they are expected to increase in height globally, and particularly in the Southern Ocean.