the ocean is a very big place..
Curmudgeon,
Agree, but several billion tones is a very big amount also. Something has to give & as the old saying goes the only way is up even if it's only 3 mm.

individual
To workout the effect of 2.2 billion tonnes of shipping on sea level all you need to know is that 1 litre of water is equal to an area of 1sq meter 1 millimetre thick and 1 litre of pure water weighs 1 kilogram.
The area of the oceans is 360 million sq kilometres or 3.6*10^20 sq millimetres
2.2 billion tonnes of shipping displaces 2.2 *10^18 sq millimetres of water 1 mm deep
Therefore the sea level rise caused by shipping is 2.2/360 mm =0.0061 mm
Note ^ meaning to the power of or in this case number zeros

Ice mass, or ice extent, which correctly measures ice loss/gain?

http://www.sciencemag.org/content/338/6111/1183
http://www.sciencemag.org/content/338/6111/1138.summary

<<I'd be seriously surprised that if all the ships ever... made the slightest difference to sea levels>>

While not buying into the argument about whether ships (& reclamation projects for that matter) make a difference...I can recall an article/study ( I think it was NewScientist) where warmists were arguing that recent floods in Asia --and the subsequent holding of water on land-- was the reason the sea levels had not risen as much as anticipated.

Warmair,
yes but 2.2 billion is only the merchant shipping, add to this the huge number of the world's navies land relaim etc. It might not be 3.2 mm but it does have an impact & cruise liners are getting more numerous & bigger. Also, due to much development more water now goes directly into the oceans instead of being soaked up by land. My point is that if we need to be worried about 3.2 mm then I'm sure we shouldn't take an additional half a mm too lightly in this scheme of things. At that rate the lowest lying land will be submerged knee-deep in only a few thosand years. better put more into your Super if the earthquakes don't get us before then by depleting all the gas & oil in the ground.

It seems that cohenite just can’t resist displaying his ignorance of climate data.

cohenite wrote “the entirely normal decrease in Greenland ice”

But is it entirely normal? This is what NOAA has to say: http://www.arctic.noaa.gov/reportcard/greenland_ice_sheet.html

“The data show that the ice sheet continues to lose mass and has contributed +8.0 mm to globally-averaged sea level rise since 2002. The rate of mass loss has accelerated during the period of observation, the mass loss of 367 Gt/y between September 2008 and September 2012 being almost twice that for the period June 2002-July 2006 (193 Gt/y).”

cohenite wrote “is more than matched by the increase in Antarctic sheet ice”

Except there hasn’t been an increase in Antarctic ice mass http://onlinelibrary.wiley.com/doi/10.1029/2009GL040222/abstract In fact the Antarctic is losing ice mass and that loss is accelerating.

“In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of &#8722;26 ± 14 Gt/yr2 in 2002–2009.”

cohenite wrote “OHC is decreasing at the surface and down to 700 meters; and anyone who thinks deep OHC is increasing will be already getting excited about Santa.”

Here is the Heat content to 700 m from NOAA http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ No signs of a decrease there. In fact there are 5 x 10^22 extra Joules of heat since 2000.

For completeness we could look at 0 to 2000 m and see that that ocean heat has increased by 9 x 10^22 Joules of heat since 2000.

So that is 3 out of 3 statements by cohenite that were completely wrong. Well 4 really, because the last one had 2 claims in it