Monday, 5 March 2012

Playing games with sea level

Also posted at OoL.
As we all know far too well, dramatic rises in sea level are one of the key catastrophes promoted by the climate alarm game. What is a little less noticeable is how quiet the sea level narrative has become. A few wild-eyed loons are still on the pitch, but many erstwhile players seem to have sneaked off down the player’s tunnel.

Because the oceans are not playing ball.

The graphic below from aviso is a little out of date, but hasn’t changed significantly. Tidal gauge readings dating back to 1870 are spliced onto modern satellite altimetry data from 1993 onwards. As you can see, the two data sets splice together pretty well.

Global mean sea level evolution over the 20th and 21st centuries. The red curve is based on tide gauge measurements [Church and White, 2006]. The black curve is the altimetry record (zoomed over the 1993-2009 time span). Projections for the 21st century are also shown. The shaded light blue zone represents IPCC AR4 projections for the SRES greenhouse gas emission scenarios. Bars are semi-empirical projections. Red bar: [Rahmstorf 2007]; dark blue bar: [Vermeer and Rahmstorf, 2009]; green bar: [Grinsted et al. 2009]. 

Allow me to note three things.

Firstly eyeball the IPCC AR4 projection range.

Secondly note the big coloured vertical bars. These are crazy projections from climate models, critically important for the but it could get much worse narrative.

Thirdly, the two newest and most accurate altimetry satellites are Jason-2 launched in 2008 and Envisat launched by the ESA, the European Space Agency in 2002 at a cost of 2.3 billion euros. This is an Envisat sea level graphic from the same source giving a rising sea level trend of 0.621 mm/year or 6.21 cm per century. In other words, about one fifth of the rise quoted in the first graphic (3.3 mm/year) and hardly something to worry about.

In fact Envisat data shows a slight decline in sea level trends over the past four years. That wasn’t the point of those 2.3 billion euros. Among other things, the satellite was supposed to confirm sea level rises linked to climate change.

Measurement of many different parameters, all affecting our global climate, its changes and the natural and anthropogenic parameters triggering such climate changes.

The rise in sea level - Envisat will improve our understanding of the causes and the impacts. 

Jason-2 has been operational for less than four years and is so far showing a rising sea level trend of 1.06 mm/year. The data series may be limited, but again it shows nothing to worry about.

 You probably won’t have seen or heard the BBC on this. They haven’t yet got round to telling us how benign Envisat and Jason-2 data is compared to the alarming claims still being made about sea level rises linked to CO2 emissions. Sea levels are rising at a rate far below IPCC projections made in AR4 according to our two newest and most advanced altimetry satellites.

It’s embarrassing. Even the most modest IPCC projections may be seriously exaggerated. Keep it quiet seems to be the current approach, so no surprises there at least.


James Higham said...

Speaking politically, what does that then say about the NPCC scientists and money? Or do some fervently believe?

A K Haart said...

JH - I think some do believe and some believe in a barrister's sense - they are paid advocates.

I suspect most have their doubts but lack the courage to be overt about it.