The Australian, Rintoul and the truth about recent research into regional mean sea level rise deceleration

Snapshot from Google search index on 23 July 2011

Stuart Rintoul is variously described as a senior journalist and/or author currently working for News Ltd’s The Australian newspaper.

On Friday 22 July 2011 he wrote an front page article loosely based on interview with Phil Watson, from the Coastal Unit in the NSW Department of Environment, Climate Change and Water.

As soon as I read the article I began to wonder at the level of misrepresentation by The Australian this article by Rintoul might involve, given the stable from which it sprang.

I went to the quoted peer-reviewed article and found that all was not as The Australian would have us believe and this NSW Government Office of Environment & Heritage letter to the editor bore out my suspicions:

Letter to the Editor - Sea-level rises slowing: tidal records
Media release: 22 July 2011
I refer to today's article titled, Sea-level rises slowing: tidal records.
Your article has misrepresented our Mr Phil Watson's research paper by saying that "global warming is not affecting sea levels". This is untrue and misleading and it is not what Mr Watson told your journalist. Mr Watson’s research looked only at measurements of historical data. It specifically did not consider predicted linkages between sea level rise and global warming predicted by climate models.
Our organisation is committed to open scientific investigation. This important research will help us understand the different contributions of the El Nino-La Nina Southern Oscillation and of climate change to sea level change. The research and underlying data is entirely consistent with the rate of global average sea level rise for the 20th century advised by the Intergovernmental Panel on Climate Change (IPCC), which was of the order of 17 +/- 5 cm.
There is strong national and international evidence that sea levels will increase substantially in this century. The world is warming and this includes the ocean. When water warms, it expands and sea level rises.
Sea level rise is a slow process but it has serious medium and long term impacts. The projections are for a rise of 40 cm by 2050 and 90 cm by 2100 in NSW, and this data is reflected in NSW policies. Our scientists are working with others to increase understanding of what and where the impacts may be, so that we can better plan for and help local communities adapt. If we are prudent now, we can substantially reduce future costs.
Yours sincerely
Mr Simon A Y Smith
Deputy Chief Executive - Environment and Heritage Policy and Programs
Contact: Public Affairs

This is a brief outline taken from Watson’s actual article published in The Journal of Coastal Research:

Is There Evidence Yet of Acceleration in Mean Sea Level Rise around Mainland Australia? by P.J. Watson

There is unequivocal measured evidence of a global average rise in mean sea level during the 20th century on the order of 17 +- 65 cm (IPCC, 2007)
….. Satellite altimeters that have been measuring changes in the world’s ocean water surface since late 1992 with improved global accuracy and reliability have focussed attention on measured global trends that appear to be increasing at rates exceeding 3 mm/y, generally in line with the upper bound projections of global average sea level rise (IPCC, 2007).
It is, however, important to understand that there will be specific localised or regional variations compared with the global average sea level rise projections. In addition to international scientific endeavours, it is imperative to analyse and understand the trends emerging from the longest Australasian tide gauge records to improve the picture of ‘‘regional’’ sea level rise to augment forecasting capabilities.
Very long, continuous records from Fremantle (1897), Auckland (1903), Fort Denison (1914), and Newcastle (1925) have been analysed to investigate whether there is evidence of acceleration in the rise of mean sea level over the longer term at these particular locations…..
The longest continuous Australasian records, Fremantle and Auckland, situated on the western and eastern periphery of the Oceania region, respectively, exhibit remarkably similar trends in the relative 20-year moving average water level time series after 1920. Both time series show a rise in mean sea level of approximately 120 mm between 1920 and 2000 with strong correlation (R2 $ 0.93) to fitted second-order polynomial trend lines that reflect a tendency toward a general slowing in the rise of mean sea level (or deceleration) over time on the order of 0.02–0.04 mm/y2. The Fort Denison water level time series after 1940 similarly reflects a decelerating trend in sea
level rise at a rate of 0.04 mm/y2 based on a strongly correlated fit (R2 5 0.974) to the second-order polynomial function.
This decelerating trend was also evident in the detailed analysis of 25 U.S. tide gauge records longer than 80 years in length (Dean and Houston, pers. comm.) and a general 20th century deceleration, driven predominantly by the negative inflexions around 1960 evident in many global records, are well noted in the literature (Douglas, 1992; Holgate, 2007; Woodworth, 1990; Woodworth, Mene´dez, and Gehrels, pers. comm.).
In considering shorter term recent accelerations, it is evident that there is a high rate of relative sea level rise averaged over the decade centred around 1994. Although average decadal rates of rise in relative ocean water levels are clearly high during the 1990s, they are not remarkable or unusual in the context of the historical record available for each site over the course of the 20th century. Similar conclusions have been drawn by Holgate (2007) in examining global data and by Hannah (2004) examining long-term sea level records for New Zealand. These recent post-1990s short-term accelerations fit within the overall longer term trend of deceleration evident in these long Australasian ocean water level records.
Using a 20-year moving average (10 y either side) water level time series limits the current analysis to the year 2000 (although the year 2000 uses data up to 2010). It is probable that if there is any longer term increase of significance in the rate of sea level rise embedded within the latter portion of the record, as distinct from a cyclical short-term attribute, this may take a further 10 to 20 years to influence the longer term time series.
Further research is required to rationalise the difference between the acceleration trend evident in the global sea level time-series reconstructions and the relatively consistent
deceleration trend evident in the long-term Australasian tide gauge records. These differences are likely to have a significant bearing on the global average and ‘‘regional’’ projections for sea level rise into the future.