On 18/01/2019 20:24, Graham Easterling wrote:
On Friday, January 18, 2019 at 7:43:09 PM UTC, N_Cook wrote:
On 18/01/2019 19:01, JGD wrote:
On 18/01/2019 17:05, N_Cook wrote:

Oceanographers seem to be comfortable with quoting IPCC projections for
SLR to 2100 but at the same time will only fit a straight line to the
Jason data.

I'm afraid that there's a reason for that, which is that they are
scientists. And a good scientist should never (and usually will never)
try to fit an arbitrary curve to a set of data, especially so when very
considerable extrapolation is involved (which is inevitably the case
when trying to forecast 80 years into the future).

The only pragmatic answer available is to use the most conservative of
assumptions or tools, which in this case is limited to a linear trend.

Obviously this creates a major headache for climate change predictions,
but the only way out is to base the curve-fitting on some sort of
defined model, which will take account of parameters like thermal
expansion of the oceans, estimated melting of land ice (insofar as it
can even be estimated roughly), and so on. I presume that there are
interdiscplinary teams that can try to put this sort of model together
and I'd guess that there this must have been happening already for a few
years. So the embryonic models must be out there somewhere in the
oceanographic literature.

But please, please, please let's not fit arbitrary functions,
exponential or otherwise, to a set of data and pretend that
extrapolation of such curves way into the future means anything at all.


Have you seen the IPCC predictions?
Well above the linear "fit" of 3.34mm per year.
I hope you can admit , that to reach such IPCC predictions, there must
be some sort of up-curve at some point.
Where is the evidence this deviation from the current "scientific"
straight line would be as late as 2080 or 2060 say , it has to happen
sometime, what is wrong in putting it where there is some evidence of
curving upwards, ie before 2020.

I think there's a danger of not seeing the wood for the trees.

AGW is resulting in a rise in sea level, which is overall a very bad thing. So is chopping down the rain forests, and removing part of the sink for all the CO2 mankind is emitting.

Filling the oceans with plastic is a bad idea, there is no need to use formulae to demonstrate what the situation might or might not be in 50 years based on a number of scenarios. Just use less bl**dy plastic! Of course, it can be recycled, Maylasia takes a lot from the UK now CHina doesn't. Seems to be working well http://www.klexpatmalaysia.com/wp-co...ls-933x445.jpg

We need to minimise our impact on the planet wherever possible, that's what's important, not the endless quoting/production of figures, IMHO.

Graham
Penzance


But stubbornly holding to "fitting" a straight line to Jason data ,
falsely implies to the AGW crowd that sea-level is rising , yes, but ar
a fixed rate. Not that the rate of increase is increasing, can be seen
if you plot out concattenated J1+J2+J3 and look at it , or more
precisely analyse it , as here.
Some media referred to exponential rise a year or 2 ago, but this
analysis shows there is no current evidence for exponential rise, but
does give some sort of justified character to the rise of rise.

Just as well the AGW lot were not aware of the recent Jason3
revisioning, which hapened to coincide with a return to upward trend
and led to a long delay in update for that public site.
(I'll place the overlay of both plots on the www so there is some public
source for it, as presumably just lost in the javascript morass of sites
such as Aviso).
Still nothing on the Aviso site as to why.
Perhaps something highly technical , change of waveguide dimensions in
weightless space perhaps, or someone placing a decimal point in the
wrong place , for the whole J3 mission.