Jason is dead . . . Long live Jason-2

First the difference between the two figures is easy to determine, they use different time periods. Over the longer time period the rate of sea level rise is higher. The short time period includes a segment where sea levels actually fell, and the given explanation is natural variability of rain fall. We can also pick short time periods to show faster sea level rise, but we should look to the uncertainly of natural variations when using either as predictive. Picking a short period, leads to the potential charge of cherry picking.

The biggest skeptic lie that seems to be pointed out from the scientific community seems to be the ties between vaccines and illnesses. There appeared one scientific article in the lancet that was later discredited for poor scientific methods. Unfortunately this one article is covered in multiple blogs claiming the damage of vaccination. Even though all the scientific evidence contradict these blogs, they have a powerful hold on the community. It is estimated this anti-vaccine hysteria has greatly increase deaths from whooping cough. Popularity of blogs has nothing to do with their scientific nature.

 

Actually we have previously referred in PC environmental to the compilation of sea level measurements over the past 6000 years. One may be forgiven for forgetting. Yes, a graph is on wikipedia and the references are there as well.

The longer (600 million year) range of sea levels is -50 meters to +250 meters, relative to the present. It is known as the Exxon curve because petroleum exploration involves a lot of sediment cores and...somehow they can deduce sea level from that. Just one more way that energy companies shed light on earth-system science (when they are not busy saving whales )

As with all the very long 'proxies', the absolute uncertainty is hard to pin down.

The 6000 year record is much more direct, from sampling of extant coral beds and 14C dating. Errors there are likely to be small. As with, oh, for example Marcott, the current SLR rate increase to about 3 mm/yr has not been of long duration. I suppose it is possible that something like this current bump (less than a century) went undetected in the coral records of 6000 years.

But this brings us back to the Medieval climate. If warming then was global and contemporaneous and of long duration, there should have been a sea-level bump. Both from ice melting and steric (thermal expansion of water) effects. Odd that such has not been reported.

 

I thought we had found such evidence of warming and cooling. I just was on a ship showing evidence of cooling in the LIA going through glaier bay. There is also evidence of previous warming in that area before the glaciers formed in 1680.

 

Medieval followed by little. Indeed, the perfect record would record both, and in opposite directions. I don't know of that from direct measures of sea level.

The Oerlemans 2005 science paper on glacial lengths
"Extracting a Climate Signal from 169 Glacier Records"
VOL 308 29 APRIL 2005 675-677;

(can be found for free with google scholar)

suggests glaciers generally retreating since 1600. Many records (such as AustinG alludes to) are local or regional.

Bob is right that sea level is a global integrator, which is handy. Needed are even better measures of level. Better to use low latitudes for that because of the rebound after the last glacial ice 'load' moved off. Another plus for coral.

 

Good plot bob. It looked a little funky to me, with the math magic of removing seasonality. Luckily the source also gave the non-adjusted levels, but you can clearly see the upward trend. If you go out to a longer series, the slope decreases (rise is accelerating). Go shorter you can choose the dip in sea levels and get a false slowing of the rise.