"I made a short speech about Houston and Dean's and Phil Watson's papers both from 2011 which showed uneqivocally that sea level rate of rise is declining"

Some more cherry picking from Anthony Cox. The rate of sea level rise is not declining http://www.cmar.csiro.au/sealevel/index.html

Do you actually know how to calculate a tangent to a curve?

"Do you actually know how to calculate a tangent to a curve?"

Show us how to apply the chain rule to the issue.

"The rate of sea level rise is not declining"

Yes it is:

http://wattsupwiththat.files.wordpress.com/2013/05/slr_rate_to2012.png

CSIRO I see relies on Church and White 2011; 2011 shows that the simple average of tide gauges shows much less exponential curve rather then two linear trends that show the the rate of rise has not changed since 1930.

So even by C&W's cherry-picked choice of data presentation there is no change.

But Houston and Dean and Watson have used different methods to analyse sea level rise; in H&D they measure sea level rise as a function of time, as does Watson who uses:

"relative 20-year moving average water level time series and fitted to second-order polynomial functions to consider trends of acceleration in mean sea level over time."

Perhaps agro can explain the relative merits of these methods, which find deceleration of sea level rise, with the CSIRO method which finds a constant rate of sea level rise.

Anthony, there is no need to apply the chain rule. If you want to know the rate of change, one merely needs the tangent to the curve at any point.

"CSIRO I see relies on Church and White 2011; 2011 shows that the simple average of tide gauges shows much less exponential curve rather then two linear trends that show the the rate of rise has not changed since 1930.

So even by C&W's cherry-picked choice of data presentation there is no change."

You do realise that no change is not a decline? For a decline in rate, the curve needs to flatten out.

Watson http://www.jcronline.org/doi/full/10.2112/JCOASTRES-D-10-00141.1 looked at 4 sites only within the Australasian region, used a moving average of the data and failed to account for divergences in the data sets. For example, Newcastle is clearly very different to Sydney, despite them being within a couple of hundred km of each other. Why would the sea level change with time be so different at two sites so close to each other? Then Watson analyses the moving average data. This is an analytical no no. If the bins overlap, then the noise in the data is not independent. This invalidates the assumption of independence required for the statistical model. Lastly, Watson uses the wrong model, one where the rate of change is assumed to be constant across the time series, when it is clearly not - and indeed Watson concludes himself that it is not. Sadly, Watson's paper is so flawed statistically as to be bunk.

As for Houston and Dean? They cherry-picked 1930 as a start. Starting at years between about 1920 and 1940 will give no rise or a small decline. Starting at any other year between 1870 and 1960 gives an acceleration of sea level rise. I wonder why that would be?

Ok, the default position here is that rate of sea level rise should be accelerating; anything other than that is a spanner in the works.

The 4 sites Watson looked at were chosen because they were the longest running sites; I don't see how you can reasonably object to that.

"Newcastle is clearly very different to Sydney, despite them being within a couple of hundred km of each other. Why would the sea level change with time be so different at two sites so close to each other?"

A couple of things about that; the records differ in length so will reflect different time based climatic conditions. It has been known that different locations on the East coast have differing sea level rates of rise; see:

http://dlibrary.acu.edu.au/digitaltheses/public/adt-acuvp29.29082005/05chapters_5-7.pdf

A host of factors can produce this difference, most natural but the man-made ones include, in the case of Newcastle, harbour dredging and local subsidence. Bob Carter has written on the disparate sea level rates around Australia:

http://members.iinet.net.au/~glrmc/RMC%20-%20aspects%20of%20sea-level%20rise%20in%20southern%20Australia%20Z.pdf

You have misunderstood both H&D and Watson. In respect of H&D they say:

"Woodworth et al. (2009) concluded there was consensus among the authors that acceleration occurred from around 1870 to the end of the 20th century; however, with the major acceleration occurring prior to 1930,the sea-level rise (Figure 1) appears approximately linear from 1930 to 2004. Church and White (2006) did not separately analyze this specific period."

They did not cherry pick 1930; the data did; as to why sea level rise accelerated upto 1930 my money is on solar recovery post LIA.

Watson doesn't overlap bins in his moving average; in fact he does the opposite; statistically this is the equivalent of a histogram with the trend being indicated in the sign of the leading coefficient.

I don't see where Watson assumes a constant rate; he says changes in the time series are non-linear and uses a method to cater for that; the only thing he appears to be finding is acceleration and deceleration of the trend.

The question you have to ask is why isn't the trend accelerating?

You are clutching at straws now Anthony.

I will go through your arguments carefully so you can see the flaws.

“The 4 sites Watson looked at were chosen because they were the longest running sites; I don't see how you can reasonably object to that.”

That is not what I objected to. I objected to the fact that 4 sites cannot represent what is happening across the globe.

“A couple of things about that; the records differ in length so will reflect different time based climatic conditions.”

Anthony, you need to go and read the paper, carefully. Have a look at Figure 2. You should notice that the pattern of change at Newcastle (top line) is totally different to that at Sydney (3rd line) both before and after the anchor point of 1940. Yet the sites are less than 200 km apart. What on earth is happening? Is sea level rising faster in Newcastle than Sydney?

“They did not cherry pick 1930; the data did; as to why sea level rise accelerated upto 1930 my money is on solar recovery post LIA.”

They chose 1930. But 1930 is the only starting time period from 1870 to 1970 when sea level rise will come out with a negative acceleration. All other starting times come out with a positive acceleration. What does that tell you?

“Watson doesn't overlap bins in his moving average; in fact he does the opposite; statistically this is the equivalent of a histogram with the trend being indicated in the sign of the leading coefficient.”

Are you on something hard tonight? Do you understand what a moving average is? Let me help you out. A moving average is where you take a series of consecutive data (i.e. years) and average them. You then move the data by one and average them again. That is why it is called a moving average. Of course the bins (i.e. years used) overlap. If the bins didn’t overlap, it wouldn’t be a moving average.

Look at a histogram;

http://www.google.com.au/imgres?imgurl=http://www.pqsystems.com/products/SPC/CHARTrunnerLean/samples/histogram.png&imgrefurl=http://www.pqsystems.com/qualityadvisor/DataAnalysisTools/histogram.php&h=675&w=900&sz=84&tbnid=DCIX7zdKzf3geM:&tbnh=90&tbnw=120&prev=/search%3Fq%3Dhistogram%26tbm%3Disch%26tbo%3Du&zoom=1&q=histogram&usg=__IPYrvB-8KY7SC0e0Auc71kAQcZM=&docid=LUWa_swnbjkUpM&sa=X&ei=TzunUfj6KcmViQeuk4GACw&ved=0CEIQ9QEwBA&dur=929

Each column is a bin; the line is the trend as a 2nd degree poly; a moving average can disguise the trend unless it is spread sufficiently wide to as Watson states:

"The fixed averaging window of 20 years is sufficiently wide to dampen the dynamic influences to reveal a transformed time series from
which signals of comparatively low-amplitude sea level rise (or
fall) can be more readily isolated."

By doing this Watson overcomes this problem:

11, 12, 13 ,14 ,15, 15, 14 ,13 ,12 11

With a 6 unit wide spread you get an increasing trend until the end of the data, which contradicts the real trend. The bins overlap and produce a false result; the trick is selecting the correct moving average; Watson has done that.

I repeat H&D DID NOT select 1930; they replicated Church and White's paper which chose 1930; H&D actually looked at the full range of data which is why they were able to isolate the problems with C&W.

I also rpepeat the issue for AGW supporters such as yourself is why isn't the trend increasing?