Realclimate has already covered this, so I won’t say much, but there is a recent paper (Kopp et al. 2016) that does a sea level reconstruction for the past almost 3000 years. The key figure is below, with the red line being the post-2000 sea level rise that wasn’t included in the paper.
An obviously interesting result is just how much this looks like a hockey stick, again. However, as David Appell points out a hockey isn’t a surprising result. Since we expect internally-driven warming to largely average out on multi-decade timescales, the dominant influences on those timescales is likely to be changes in external forcings. Since the largest change in external forcing in the last few thousand years has probably been the anthropogenically-driven change over the last 100 years or so, we would expect the largest change to be over the last century or so; a hockey stick. In fact, if you look at the Realclimate post you’ll see another figure that illustrates that the change in sea level in the last century is much greater than in any century in the last 2000 years.
Given that sea level rise is a proxy for changing energy in the oceans, this is a really nice confirmation of what millenial temperature reconstruction have been illustrating for the last 18 years or so. I guess the one question is; where is the Medieval Warm Period? There’s maybe some suggestion of a slightly warmer period ~1000 years ago, but nothing like what what’s happened in the last 100 years or so. Admittedly, this is apparently the first attempt to do a multi-millenial sea level reconstruction, so one should be careful of jumping to conclusions. However, it’s certainly very interesting and largely confirms what we already know; our current warming is unprecedented when compared to the past few thousand years.