Saturday, September 14, 2013

New Ocean Heat Data

NOAA just put up the global Ocean Heat Content data for the second quarter of 2013: 0-700 m region, 0-2000 m region.

The numbers are down slightly from the previous quarter (by 12.4 ZJ and 25.2 ZJ, respectively); on the other, the 1Q13 results were revised upward (by 8.4 ZJ and 10.9 ZJ respectively).

1 ZJ = 1 zettajoule = 1021 Joules = 15.9 million Hiros, where 1 Hiro = yield of Hiroshima bomb = 63 TJ = 63 terrajoules = 63 trillion Joules

These are cool units but a little ridiculous; for changes and trends it's easier to use terrawatts -- which is more prosaic since all of humanity's average energy consumption is about 15 TW (= 1 Civ) -- or Watts/square-meter, where you can divide by the total area of the ocean (361.8 Mkm2) or, since over 90% of the greenhouse-trapped heat goes into the ocean, by the total area of the Earth (510.1 Mkm2).

Then, the 12-month change in OHC is

0-700 m: 22.7 ZJ  <-->  718 TW = 48 Civ = 2.0 W/m2
0-2000 m: 24.4 ZJ  <-->  773 TW = 52 Civ = 2.1 W/m2

where I used the total ocean area. The 15-year trend for the 0-700 m region is 0.41 W/m2. There is only 8 years of quarterly data for the 0-2000 m region (roughly the top half of the ocean); it's trend over that time is 0.52 W/m2.

The 0-700 m region has warmed 37% more in the last 15 years than in the previous 15 years, which goes some way towards explaining The Pause.

Invariably someone will complain that these large heat changes represent a temperature change of only a small fraction of a degree Kelvin (via the definition of specific heat, ΔQ = mcΔT), to which the correct answer is, "yeah, so what, it's a big planet, we ought be measuring temperature in energy units anyway, as they are just related by a constant (Boltzmann's) that in a perfect world would have been set equal to one and done away with."


bahamamamma said...

Even the faithful Dano seems to have abandoned you. Maybe he (she?) is on vacation.

I got to wondering why someone who writes so well completely fails to attract an audience while less educated people such as J.K. Rowling become wealthier that the queen of England.

You both write fiction. Measurements of the heat content of the oceans are essentially worthless prior to the advent of the Argo buoys in 2000.

David Appell said...

Measurements of the heat content of the oceans are essentially worthless prior to the advent of the Argo buoys in 2000.

NOAA scientists don't think so. What do you know that they don't?

Unknown said...

OHC is truly the best way to measure AGW. It's very clear, if anything, the positive forcing of GHGs has continued to grow based on the heat accumulations in the ocean. The truth is skeptics will find a way to question the data until it's suits their preconceived notions. Notice how the surface temperature record magically does not have any issues the last 10 years?

It's truly nonsense. On another note, keep up the good work. I enjoy reading your blog.