Future prospects - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 353

rising CO 2 . It is noteworthy that they claim a strong correlation between glacier
advance and retreat with atmospheric residual 14 C which, according to some
theories, is a measure of the activity of the Sun. Yet, this correlation appears to
lie more in the eye of the beholder than in the data.
11.1.4.4 Sea level rise
IPCC (2012) is a 1,000-page report describing the putative impacts of global
warming on humanity. While many of these impacts ranged from dubious to
ridiculous, one potential impact stood out as a serious concern: sea level rise.
Hansen (2004) said: ''The dominant issue in global warming, in my opinion, is
sea-level change and the question of how fast ice sheets can disintegrate.''
However, the issues involved in ascertaining the effect of global warming on
sea level rise illustrate the complexity and uncertainty involved in predicting the
future. Kolker and Hameed (2007) said:
''Determining the rate of global sea level rise (GSLR) during the past century
is critical to understanding recent changes to the global climate system. However,
this is complicated by non-tidal, short-term, local sea-level variability that is
orders of magnitude greater than the trend.''
Fjeldskaar (2008) echoed this viewpoint, saying that ''relative sea level changes
are not the same as eustatic changes'' and ''it is dicult to imagine where a
eustatic change can be measured realistically.''
Douglas and Peltier (2002) pointed out that the measurements of relative sea
level (RSL) at any location have large annual and decadal fluctuations that tend
to obfuscate long-term trends as a result of noise. Consequently, only very long-
term records have the potential to accurately provide the underlying trend. A
CNES analysis showed that the use of only four decades of data at tide gauge
sites led to an overestimate of GSL rise. Other studies showed that the extreme
dependence of trend on record length is real—not an artifact of the tide gauge.
Specific measurements of sea level rise have been made by means of tide
gauges and satellite observations. Cazenave and Nerem (2004) found that sea level
rise for the decade 1993-2003 was 2.8 0.4mm/yr, as determined from TOPEX/
Poseidon and Jason altimeter measurements, rising to 3.1mm/yr if the effects of
post-glacial rebound are removed. This rate is significantly larger than the
historical rate of sea level change measured by tide gauges.
Lombard et al. (2005) found large oscillations in decadal changes in sea level
due to the El Nin˜ o-Southern Oscillation (ENSO) and the Pacific Decadal Oscilla-
tion (PDO), and cautioned against extrapolating short-term sea level data from
satellite measurements.
Sea level rise as measured by tide gauges provides a different picture. Holgate
and Woodworth (2004) estimated sea level rise from 1952 to 1997 (45 years) based
on 177 tide gauges from 13 regions with near-global coverage, and then used a
glacial isostatic adjustment model to correct for land movements. Sea level rise