UPDATE 23 January 2010: Adelaide University Professor Barry Brook was kind enough to provide the authoritative resources for monitoring of sea level rise in the area of Vanuatu. I have escalated Barry’s comment here to the top of the post so that new readers of this post can easily go directly to the SeaFRAME programme, which is the superior resource for further information:
You need to correct for crustal movements and a range of other biasing factors in order to accurately assess localised sea level rise. This is standard practice. The most comprehensive monitoring of the SLR in the Pacific Basin and Australia is the SeaFRAME (Sea Level Fine Resolution Acoustic Measuring Equipment) programme, which includes coverage of Vanuatu:
Latest Vanuatu report here:
With all appropriate corrections applied, the rate for Vanuatu is 2.5 mm/yr.
Dear reader, I recommend that you proceed directly to the SeaFRAME links above provided by Dr. Brook â€” don’t bother reading the rest of this post. Lastly, for a superior resource on energy policy that can have a real impact on global climate change I recommend that you investigate Dr. Brook’s website BraveNewClimate.com.
ORIGINAL POST CONTINUES: What is the real story on sea level rise? Is catastrophe already producing fleeing populations? I’ve started looking into the measurements that have been published. E.g., the above local trends map is from the University of Colorado at Boulder sea level change project.
Local trends are calculated with a least-squares fit of 10-day, 1-degree resolution grids of sea level. A trend, bias, annual, and semi-annual terms are fit simultaneously.
Please note that these trends have been determined for only a fourteen-year period, and reflect the impact of decadal scale climate variability on the regional distribution of sea level rise.
The next chart shows the global average satellite altimetry data from 1993 through 2009. The trend over that period continues to be around 3.2mm per year. So far there is no evidence of accelerating sea level rise. The global mean change in sea level over the 1993-2009 period is about 50mm or 2 inches.
The data is very noisy. Below the trend chart is a global map showing the variance of the local trend data plotted above. On quick inspection it appears that the “hot spots” showing high positive increases have variance almost as large as the signal.
Local changes can be very different from the global mean, including falling sea level trends. To investigate local trends there is an interactive display tool. Here I found my knowledge of the data and processing procedures lacking. E.g., I don’t understand why the local trends map I have displayed looks very different from the first map shown above.
So, more homework to be done. What is the truth and significance of this meme
The people of Vanuatu are already feeling the pointy end of climate change. Rising sea levels, bleached coral reefs and turbulent weather is affecting VanuatuÂ’s tourism and its main export, coconuts. In late 2005, an entire coastal village in northern Vanuatu was relocated to higher ground. One hundred residents of Tegua Island became the first climate change refugees.
We just spent two months cruising New Caledonia which is just south of Vanuatu. We saw no evidence of material sea level rise anywhere in New Caledonia. Similarly, we met with a number of other yachts who have been cruising Vanuatu – nobody reported anything unusual there.
UPDATE: In the comments, John Nicholls has contributed some first-hand reports on the Maskelynes group in Vanuatu. I emailed John regarding sea level rise datum “When you report one meter/year rise are you measuring vertical -> water level height; or horizontal -> lost beach?” John replied “horizontal”. So we have anecdotal evidence of increasing horizontal beach coverage. The UC Boulder satellite data above shows a maximum of 15mm/year rise in that general part of the South Pacific. At a beach slope of 1:67 that translates to one meter per year of “horizontal breach drowning”. I would guess the beach slopes are more like 1:20 so there is a factor of 3 mismatch between the satellite observations and John’s anecdotal report.