Are sea levels rising or are the figures being 'adjusted'?

'Is climate change raising sea levels, as Al Gore has argued — or are climate scientists doctoring the data?
The University of Colorado’s Sea Level Research Group decided in May to add 0.3 millimeters — or about the thickness of a fingernail — every year to its actual measurements of sea levels, sparking criticism from experts who called it an attempt to exaggerate the effects of global warming.
“Gatekeepers of our sea level data are manufacturing a fictitious sea level rise that is not occurring,” said James M. Taylor, a lawyer who focuses on environmental issues for the Heartland Institute.'

Hot Air  have the details and this explanation:

'Why the revisions? Apparently they claim that it’s because of glacial isostatic adjustment. Basically it describes the gradual, slight rise of continental land masses which means that the ocean basins can hold a bit more water. (Again… who knew?)
So it looks like the institute decided to fudge the sea level data a bit to represent how high the levels would be if land wasn’t rising also. I don’t know about you, but if the major concern is ocean levels rising and swallowing up the coastlines, I’d think you’d want to measure the actual ocean levels, no?'

Badly positioned weather stations, disappearing weather stations, 'adjusted' temperature records (always upwards) and now 'adjusted' sea level rises (upwards again) - it's all looking a bit 'dodgy', isn't it?