Over the past year I have done several articles about the rise of the sea level. It certainly looked likely at this time last year that the sea level in 2010 would be lower than 2009. That would be twice in the past decade that the sea level did not rise from one year to the next. That the sea level was not rising is a real problem for warmists everywhere. This was evident because the sea level data has been revised not once, but twice this year. Both revisions included adding built-in linear trends in the data so the trend from the 1990’s would continue in the official data. I extensively reviewed the latest update about a month ago.
Since then the data has been updated, but I have not detected any further revision to the data, which is almost news in itself. The latest update brings the current RSL (relative sea level) data through about the beginning of August for the current year. Since that puts the data more than halfway it is safer to start making predictions.
For the Jan-July period, 2011 is running ~5.5mm lower than 2009 and 2010 and is ~1mm higher than 2008 for the same period of the year. 2011 is so far behind the last two years that there is no chance it will catch up. 2011 will have a significant drop from the past two years.
The problem is that the behavior since 2004 is different and a linear regression is basically meaningless in this case. I show it only because that is the standard methodology. The rate of change for the RSL from 1993-2004 was ~3.6 mm/yr. Since 2004, the rate has been less than 2mm/yr. That is even with the data that has a built-in linear trend as shown here.
If I go back and reconstruct the original data using the same method as I did earlier, the change in RSL behavior is even more apparent.
According to the original method that was in use until September of 2010, the rate of sea level change from 2004-2011 is only 1.2 mm/yr. The rate shifted in 2004 and has not been the same since. Only through aggressive data manipulation is the constant rate of change shown.
What I find most interesting in the reconstructed data is that 2010 would have been nearly identical to 2009. The official data put 2010 at 0.9 mm higher than 2009. That is now becoming a problem as 2011 is now looking to be 5.5 mm lower than 2010. The reconstructed data shows that 2010 was basically unchanged (-0.004mm) from 2009, but then 2011 is only going to be -5.1 mm lower than 2010. So by bumping up 2010 like they did, they created a greater drop in the sea level this year.
It also appears that they are not going to revise again anytime soon because they are ready for this years drop in the sea level. SkS ran an article that was recently updated showing that extra rainfall around the world is the cause of the sea level drop. The most amusing part of this article is that it requires that the period of time between March of 2010 and March of 2011 had more rainfall than has ever been experienced before in modern times. Almost as amusing is the idea that only the extra rainfall locations matter and the extra rainfall locations are not balanced out by the drought locations which are readily apparent.
So even though the regions that lost water are comparable to the regions that gained water, it is the rainfall that caused the sea level to drop. Once again I am left shaking my head at the rationalizations that must be made to fit everything into the neat little box of global warming.
The real problem with this proposed theory is that it is not a one year change. The RSL rate changed 7 years ago and shows no evidence that the rate will pick up again any time soon. The original data shows that 2005 had a RSL of 23 mm. 2011 is on track to have an RSL of between 26-27 mm. That is a change in RSL of 3-4 mm in a 7 year period. That is not a one year anomaly, that is a change in behavior.
So while the warmists and their supporters will continue to persist that the RSL dropped only because of a one year aberration, the reality is that the behavior of the sea level changed 7 years ago, but it isn’t evident because they keep tinkering with the data. The rate of sea level change continues to drop. The current deceleration of the sea level is -0.13 mm/yr^2. That number means nothing by itself, but is simply a measure that over the past 10 years, the rate at which the sea level is changing has been decreasing over that entire period of time.
This remains the most useful way of looking at the RSL for the past 7 years. We could play find the trend, but since no significant trend exists, I find little reason to play that game.