No increase in the rate does not mean no increase. Clearly there is an increase. You want a hockey stick? Wait for Greenland to melt. You may well live to see that.
Humans have been dealing with and adapting to the natural rate of sea level rise for hundreds of years. Most of Florida, most of Manhattan, almost all of Louisiana, and many, many other highly-populated areas were uninhabitable swampland before we learned to master sea level and the slow, natural rise that has gone on for as long as we have been making scientific measurements.
This panic about rapidly rising seas is nonsense. No Pacific islands have "disappeared" due to sea level rise, nor have any Arctic or Alaskan villages -- those that have seen changes are due to subsidence, not rising seas.
If you want to attribute the 160-year record of slow, steady, 2-3mm/year (2-3cm/decade) natural rise in sea levels to some mysterious factor that has been in place since CO2 levels were below 300, let's hear your theory. Otherwise, there is nothing to be alarmed about.
Here in reality, I actually live on an island. And our 100-yr flood lines just got moved in, meaning 2000 houses that weren't considered at risk of flooding are now having to deal with flood insurance or lack thereof.
Modifying flood insurance coverage maps isn't anything new, either, but any changes being made should not be blamed on an INCREASE in the rate of rise, because there is no INCREASE in the rate of rise.
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edit: In response to Jtsummers below, since HN thinks posting more than 3 times per day is too quick:
>If the radius of the balloon increases at a constant rate, the volume of the balloon is increasing at a much greater rate (specifically, proportional to the cube of the increase in radius).
Sure, but we're talking about a numerical value which moved ~20cm over the entire measurement time, compared to the balloon which is 1,270,000,000 cm in diameter. The effects that you mentioned are entirely negligible and probably even beyond the resolution of our measurements.
Consider by way of analogy a balloon. If the radius of the balloon increases at a constant rate, the volume of the balloon is increasing at a much greater rate (specifically, proportional to the cube of the increase in radius).
By reducing the discussion to merely the sea level, we are ignoring the fact that we must add increasingly large amounts of water to the oceans each year to maintain even a linear rate of growth of sea level.
It should also be noted that since the oceans are not in an arbitrarily deep cylinder, as the oceans rise they will also increase in spread (overtaking what is presently land). If the rate of water going into the oceans were constant, we should expect a sub-linear increase in sea level due to this as well.
EDIT: The only way to have both a constant increase in volume and a constant increase in sea level would be if the oceans stopped at their present boundaries and went straight up sheer walls. I rather doubt this is the case.
The balloon was strictly meant as an analogy, but it is illustrative and establishes the upper bound on the rate of increase of water volume.
Regardless of that, showing a linear increase in sea level (constant rate) still necessarily implies a non-constant increase in water volume due to the shape of the "container" for the oceans. Our oceans are not bounded by sheer walls, so it must also be increasing in surface area (spread over land). If it is increasing in surface area and still increasing linearly in sea level [0], then the volume is growing at a super-linear rate. That means each year more water is going into the oceans than the prior year (on average, at least).
[0] One measure from San Francisco, of course, is not enough to demonstrate this as there will be lots of local variations due to many factors.
I agree with the logic of your statement - it is perfectly sound. My point was that for a large enough balloon and a small enough rate of increase, the effect will "look" linear(e.g. look at the domain [4.1,4.125] of e^x and determine if it is a linear or exponential function), and our instruments (probably) can't even begin to measure for the effects which you propose.
So far this season, Greenland is gaining about 50 gigatons PER DAY in ice -- and the rate of gain is INCREASING.
https://beta.dmi.dk/uploads/tx_dmidatastore/webservice/b/m/s...
https://beta.dmi.dk/en/groenland/maalinger/greenland-ice-she...
http://www.arctic.noaa.gov/Report-Card/Report-Card-2016/ArtM...
Greenland is losing ice at around 200Gt/year (this is also in your second link). And I don't see where you get the 50Gt/day gains. Unless the graph is lying, it's in Gt/day. Ranging from gains of about 12Gt to losses of about -8Gt over this past year. Quoting your source:
Over the year, it snows more than it melts, but calving
of icebergs also adds to the total mass budget of the ice
sheet. Satellite observations over the last decade show
that the ice sheet is not in balance. The calving loss is
greater than the gain from surface mass balance, and
Greenland is losing mass at about 200 Gt/yr.
Temperatures in the center of Greenland's ice sheet never rose above -10C all summer, so it's hard to see how it could have lost any ice. Ice accumulation is nearly two standard deviations above the 1981-2010 mean for the same period, and it is very, very early in the season for such gains.
Both of Greenland's largest glaciers (Jakobshavn and Peterman) are growing at record rates, about 1km/year.
Icepacks and glaciers calve into the sea. That's what they do. It's Nature's way of moving the ice and snow away from the center and back into the ocean. If they didn't, the snowpack/ice would extend to the Equator, which is impossible, or the snowpack would be 5 miles high, which is not the case.
If it were true then the chart should show well in excess of 200Gt accumulated for this year so far, and it does not. In September they have so far accumulated 50Gt which is in line with previous years at this point.