Realclimate is a website which promote the theory of man-made global warming and that the warming will be catastrophic. They are known for being dishonest, censoring information which contradicts their own, and for being run by people claiming to be scientists who are anything but scientific.
Their latest post, Is Sea-Level Rise Accelerating?, is trying to distract from the fact that the sea level rise has been decelerating over the last decade or so. In order to “debunk” this they show this chart:

Ah yes, very interesting chart. For one thing, you’ll notice that it cuts off the recent decades where it is decelerating, but there is something that is even less obvious if you don’t follow this sort of thing – the greatest acceleration in sea level rise, from their chart, is from 1940 to 1970 – which is a time period when global temperatures were cooling even by the GISS datasets put out by the members of Realclimate:

That is their temperature data. I hate to link to it since it is so inaccurate and dishonest, but you can clearly see the cooling from 1940 to 1970.
So again, why did the sea level rise accelerate so much when it was cooling? According to these people the sea is rising from melting ice and thermal expansion. This means the connection between sea level rise and temperature is not that great – or their instruments are woefully inaccurate (surface stations or tidal gauges).
My comment pointing this out to them was of course deleted without comment, which is typical of climate “scientists” who don’t like their dogma, and the gravy which flows from it, questioned with inconvenient truths.