Here is plot of sea levels at Swansea, United Kingdom using monthly data downloaded from PSMSL downloaded on 13 August 2014.
The line shows the linear trend.
Does the 3mm/year rate claimed by IPCC seem credible to you?
Accelerating rates of sea level rise are supposed to be produced by rising global temperatures.
And what does it mean if sea levels fall, as they are in some locations? For example: