Sea Level Rise Slows by 20%
January 7th, 2009Posted by: Roger Pielke, Jr.
Efforts to sell climate policy based on ever more scary scenarios of apocalypse cannot be sustained and are likely to work in exactly the opposite manner than desired. A good example of why this is so can be found in a recent paper (hat tip Dad) that suggests that the rate of sea level rise from 2003-2008 (2.5 mm/year) is 20% lower than that presented by the IPCC for 1993-2003 (3.1 mm/year). Whether this is “consistent with” longer-term predictions is different that whether it is “consistent with” a political strategy based on scaring people. It seems pretty obvious that systems that exhibit a large amount of variability or are simply poorly understood on relatively short time scales are not very useful props in efforts to show the world moving inexorably towards doom.
Cazenave, A., et al., Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo, Glob. Planet. Change (2008), doi:10.1016/j.gloplacha.2008.10.004 (PDF)
Popularity: 2% [?]
January 7th, 2009 at 12:18 pm
This reminds me of the CCSP’s Unified Synthesis Product [USP]. It trumpeted as a “key finding” (no. 2), which it claimed was novel, thusly: “Many climatic changes are occurring faster than projected even a few years ago.”
In my comments, I noted that: “this is based on cherry picking of information. While many climate changes may be occurring faster than projected, many others are not. For example, global temperature has not warmed significantly over the past dozen years or so (see e.g., http://vortex.nsstc.uah.edu/public/msu/t2lt/tltglhmam_5.2), the oceans may not have warmed as much as expected (e.g., Lyman et al. 2006; Willis et al. 2007, 2008), and there are recent papers that suggest sea level may not be rising as rapidly as suggested by the IPCC’s latest report (Berge Nguyen et al. 2008; Unnnikrishnan and Shankar 2007; Kolker and Hameed 2007; Woppelmann et al. 2007; see also http://sealevel.colorado.edu/, which suggest slowing of sea level rise). In any case, regardless of whether recent data show ups or downs, it’s not clear that these short term blips will become long term trends. Accordingly, Finding 2 should be jettisoned, or it should be modified to: (a) acknowledge that many other climatic changes may not be occurring as rapidly as projected, and examples provided above should be included, and (b) note that it is downright unscientific, if not risky, to base long term policy on short term data, particularly when it comes to climate change, itself a long term phenomenon.”
I also noted with respect to another “key finding” that: “There is a tendency in [the USP] to treat recent trends as harbingers of future long term trends. For example, there is the statement (previously noted) that some changes are happening faster than anticipated. Similarly, Key Finding 4 states that ‘Atlantic hurricane intensity has increased in recent decades…’ But data going back to 1970 or so are too short to be used to make definitive statements about whether changes in intensity are due to climatic trends, short term natural variability, improvement in detection technologies with enhanced spatial and temporal resolution, or a combination of all these factors. In the long term context, it’s not clear whether these changes, if any, are outside the bounds of natural variability. [I note that one doesn’t normally see analysis that rules this out as a hypothesis, which I believe is a major shortcoming in climate change science.]
My comment, of course, cuts both ways. Protagonists/observers on both sides of the climate change debate should be fully aware of the data and cognisant of short term variations, but not mistake them for long term trends. To do so, means we are assuming we know more than we actually do.
January 8th, 2009 at 11:57 am
More disagreement with IPCC here:
On the decadal rates of sea level change during the twentieth century
GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L01602, doi:10.1029/2006GL028492, 2007
S. J. Holgate Proudman Oceanographic Laboratory, Liverpool, UK
Abstract
Nine long and nearly continuous sea level records were chosen from around the world to explore rates of change in sea level for 1904–2003.
These records were found to capture the variability found in a larger number of stations over the last half century studied previously.
Extending the sea level record back over the entire century suggests that the high variability in the rates of sea level change observed over the past 20 years were not particularly unusual.
The rate of sea level change was found to be larger in the early part of last century (2.03 ± 0.35 mm/yr 1904–1953), in comparison with the latter part (1.45 ± 0.34 mm/yr 1954–2003).
The highest decadal rate of rise occurred in the decade centred on 1980 (5.31 mm/yr) with the lowest rate of rise occurring in the decade centred on 1964 (1.49 mm/yr). Over the entire century the mean rate of change was 1.74 ± 0.16 mm/yr.
January 10th, 2009 at 9:46 am
[...] in assessing the scientific validity of these speculations, especially since in many cases the observed data doesn’t match earlier predictions – collectively, we still have a lot to learn about the true impacts of anthropic climate [...]
January 15th, 2009 at 7:05 am
[...] than in journals’ – Analysis: The UN IPCC Numbers Game: 4000 scientists = 60 scientists – Study finds Sea Level Rise Slows by 20% – Lower than IPCC Estimates! – ‘No evidence for accelerated sea-level rise’ says Royal Netherlands Meteorological [...]
January 15th, 2009 at 7:41 am
[...] This article explains that sea level rise is currently 20% below the recent average stated in the IPCC report. [...]
January 28th, 2009 at 2:47 pm
[...] has cooled since Gore’s film was released, Antarctic sea ice extent has grown to record levels, sea level rise has slowed, ocean temperatures have failed to warm, and more and more scientists have publicly [...]