Unformatted text preview: ted 1. the series of global mean sea level (deviation global
n1980-1999 mean) in the past and as projectedthe uncertainty in the estimated long-term rate of sea level
ot available. The grey shading shows for the future. For the period before
1870, global measurements of seaare from tide gaugeThe grey shading shows 1990s, from satellite
change. Instrumental records level are not available. records and, since the
he uncertainty in the estimated long-term rate of sea level change
atltimetry. Uncertainties in future projections result from (Section 6.4.3). of different emission
The red line is a reconstruction of global mean sea level from tide gauges (Section
scenarios for greenhouse gases, mainly CO2. (source: IPCC report)
188.8.131.52), and the red shading denotes the range of variations from a smooth curve.
The green line shows global mean sea level observed from satellite altimetry. The
18.3shading represents the range of model projections for the SRES A1B scenario
blue Global Warming and Sea Level Rise
for the 21st century, relative to the 1980 to 1999 mean, and has been calculated
independently from the observations. Beyond 2100, the projections are increasingly
Rising temperatures lead to thermal expansion of the water in the oceans
dependent on the emissions scenario (see Chapter 10 for a discussion of sea level
melting of glaciers considered in this Both results in a rise or
rise projections for other scenariosand ice sheets.report). Over many centuries in sea level.
millennia, seao Icould rise by several metres (Sectionlevel has risen by 15cm
level n last 100 years, global sea 10.7.4). o
o and Estimated contributions to sea level rise:
thermal expansion: 30%
melting of glaciers: 20%
melting of Greenland ice sheet: 20%
melting of Antarctic ice sheet: unknown but likely large NB: the melting of sea ice (icebergs) does not contribute to sea level rise! The
icebergs floating in seawater already displace the seawater of equivalent weight.
So when the icebergs melt, they displa...
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