cohenite and others,
With regard to warmth, I think of algae only as mass, increased mass. Increased unnatural mass. e.g cast iron mass v/s copper mass - difference.

I do not see green ocean algae generating warmth.
The slight warmth in ocean algae I am on about originates from the sun. But when warm algae mass covers a vast area, I think considerable warmth is involved.

As for cyanobacteria I was not aware it produces energy.
In 2000 I personally observed estuary sediment dispersed on Surfers Paradise beach, which led to the beach northerly flowing alongshore current causing a 30-40 sq km RAMSAR seagrass site at Amity Banks to be destroyed for the season. Consequently mass starvation of mutton birds occurred with mortality along coast from Rockhampton to South Australia and around Tasmania.

The algae with the warmth I notice is primarily the green algae, the chlorophyll green pure vegetable matter algae. Look for green in water.

NASA shows coccolithaphore phytoplankton with limestone (calcite) shell and chlorophyll. I think the limestone shell forms an even greater increase in mass capable of absorbing and storing solar heat, for a short but perhaps important period of time. The huge mass in the Bering Sea is where ice is reported melting more than usual.
http://earthobservatory.nasa.gov/Features/Coccolithophores/

Note the following link, "never observed" in such mass until the 1990’s.
When was the unusual ice melt first seen?
http://earthobservatory.nasa.gov/Features/Coccoliths/bering_sea.php

And why is the real state of the ocean environment not out there in news and debate about world food security issues, and AGW issues?

Cyanobacteria (aka blue-green algae), like algae, photosynthesize.

The specific heat capacity of limestone is less than water's, so its thermal inertia is lower i.e its temperature variation over 24 hours is greater than water's, its temp ranging lower and higher for the same amount of heat absorbed or radiated. Regardless of the material the quantity of heat energy emitted or absorbed are the same.

Sorry, couldn't stand by when a further small dose of physics might yet open JF Aus' mind to the inconvenient truth. Just kidding, of course:-)

"Regardless of the material the quantity of heat energy emitted or absorbed are the same."

You need to check that, starting here:

http://scienceofdoom.com/2010/07/31/the-amazing-case-of-back-radiation-part-three/

Noting this:

http://scienceofdoom.files.wordpress.com/2010/03/emissivity-vs-wavelength-various-substances2.pn

The emissivities of limestone or white marble (calcium carbonate, comprising phytoplankton skeletons) and water are all around 0.95 (max possible = 1.00). Water has a higher specific heat, so its temperature rises/falls faster than whatever might displace it (algae/phytoplankton)

Regarding back-radiation and "The world we live in does absorb DLR and adding 300W/m2 to the surface energy budget is the reason why the surface temperatures are like they are." If this is so it has always been so....yet we have the hockey-stick. Furthermore, even assuming this is correct, it neither support JF's hypothesis for AGW, nor falsifies it.

What JF needs is a published study of his hypothesis for AGW, not speculative obfuscation of the accepted one.

"...so its temperature rises/falls faster..." that should be "slower", of course.

"yet we have the hockey-stick."

Your side have the Hockeystick lucie; sceptics used it for firewood some time ago.

We'll see which way the cinders fall after Mann vs Steyn.