That is pretty simple in my opinion. Like Einstein said, "The goal of science is to make things simple, but not simpler than it is." or something like that. That cartoon fits the bill. Now remember, other than a small amount of heat generated in the Earth's core, people burning stuff and lightning etc., all the energy we get, comes from the sun. Yeah, the volcanoes blah, blah, blah, all that stuff are very small in relation to the energy we get from the sun. That is part of the art of simplification, knowing the significance or scale, so somethings can be approximately as zero.
There are a few people that are not into simplicity. They like to make it look like they really earned their money doing science by showing how complicated the stuff they did was. Kevin Trenberth and his buddies are a couple of those kinda guys. Kevin was the guy in the climategate emails that said it was a "travesty" that there was missing heat from his radiation or energy budget for the Earth. Here is what his cartoon looks like.
That is Kevin's old 1997 cartoon, he has a new one published in 2008 in this Earth's Energy Budget Paper. There are a few change in the new paper, The main ones I what you to note are the surface radiation in the new one is 396 and the back radiation is 333. Most normal folks would take the 396 minus the 333 and get 63. That 63 is the net outgoing longwave radiation leaving the surface of the Earth in Watts/Meter squared. The top of his new cartoon has 341 coming in at the top of the atmosphere and 239 leaving as longwave radiation and 102 reflected by clouds and other shiny stuff so the energy in is the same as the energy out.
Now Kevin didn't complicate things just so he could. Kevin needs to prove that CO2 is causing global warming. I say "need" because many of the research grants actually state that the purpose of the research they are being paid for is to "prove" CO2 and other greenhouse gases that man has contributed to are causing global warming. I find that humorous, kinda like they find the tobacco companies paying for research to "prove" smoking was not bad for you. The tobacco guys though were bad and Kevin and the gang are good, so there is no comparison of course. So Kevin is trying to use this back radiation as a separate thing, than just using the net like most folks would. This concept leads to some funny circular logic.
One paper I read states that 70% of the surface warming is cause by back radiation and that 65% or so of the atmospheres warming is caused by surface radiation. So one thing is warming the other which is returning the warming, which it will get back most of. Now remember, nearly every damn bit of the energy comes from the sun. Also remember that CO2 is not a little miniature sun generating energy, it is just getting energy from the radiation or heat leaving the Earth and spitting it back out after a short while. The clouds and the atmosphere don't have generators, the Earth does, but we said that was not big enough to worry about, so say the Earth doesn't generate heat either. The Earth, clouds and all the molecules have some temperature so they have some heat content. Anything with a temperature radiates heat energy in the form of infrared radiation, but heat only flows from warm to cold, except for a minuscule amount that doesn't really heat anything, it is just good for mental masturbation exercises.
If we floated between the Earth and sky with one of those infrared thermometers that you can point at stuff and read a temperature, we would prove that, yep, those clouds up there are about -50 degrees and the dirt down there is about 20 degrees. Results of course would vary, but you get the drift.
This concept has some people that sound intelligent saying the the oceans are warmed by the clouds mainly and the sun warms the oceans a little bit. Nope, I am serious! While it is the atmosphere warming the oceans in their minds, clouds make the warming stronger. Now stop laughing. These guys are serious and are getting paid to come up with this stuff.
Now if you take a white rock and a black rock and set them in the sun, the black rock gets hotter right? That is the sun's energy being converted into heat because black absorbs more sunlight than white. Black has what is call a low albedo and white, which reflects most light has a high albedo. What is the albedo of the ocean you ask? Since you asked, 0.06 is about the average albedo of the ocean. That means that 94% of the sunlight is absorbed and converted into heat while 6% is reflected. Unlike a brick, the ocean does not absorb all that solar energy at the surface. Just like you can bent sunlight with a prism or watch raindrops bent it into a rainbow, different colors of light penetrate deeper into the ocean. Red light doesn't make it too far, it only goes about 30 feet. Orange and yellow make it to about 90 feet, green, blue and violet make it all the way to 300 feet. Now not all of each color makes it all the way to the maximum depth they can penetrate. They get absorbed a little bit along the way. So the top 30 feet of the ocean gets most of the warming, the top 90 feet gets the second most and there is even a little warming down to 300 feet. Oddly enough, there are these things called thermoclines, temperature breaks in the ocean. The biggest one is at 300 feet. There is normally one around 90 feet and sometimes a little one at 30 feet. Those depths vary a little since there is some mixing and some conductive heat transfer. But the ocean is weird, it don't always conduct heat that well, so you can get these weird temperature breaks and currents like the Gulf Stream that carry warm water from the tropics all the way to the North Sea.
While some of the sun is reflected by the clouds, 184 Watts/meter squared makes it to the ocean surface and 94% of that is absorbed so 173 Watts/Meter squared warm the ocean on an average day. That is using Kevin's numbers. Using NASA's numbers, 55% makes it to the ocean surface so of that 176 Watts/Meter squared is absorbed. Those numbers are pretty close, I just wanted to show that Kevin's number is a little lower. Remember that Kevin is the one bitching about the "Travesty" of the missing heat.
In Kevin's paper that goes with his cartoon, there is some interesting stuff for a guy like me that used to make money measuring things. That is instrumentation error. "As noted in the “Datasets” section, the TOA energy imbalance can probably be most accurately determined from climate models and Fasullo and Trenberth (2008a)reduced the imbalance to be 0.9 W m−2, where the error bars are ±0.15 W m−2." So Kevin and his buddy Fasullo have nailed the TOA energy down to 0.9 W m-2 +/- 0.15. That is what I used to call getting it as tight as a gnat's ass. "On average, the oceans surface energy flux was +21 W m−2 (downward), indicating that major biases are present.
They suggest that the net surface radiative heating may be slightly too large (Zhang et al. 2004), but also that latent heat flux variations are too large." +21 W m-2 indicating major biases, is more like the real world stuff I had to deal with. Test instruments will lie to you if you are not careful. Now note that,"most accurately determined from climate models" line in Kevin's gnat's ass value. NASA's cartoon is based on real measurements, with real margins of error, while Kevin is modeling stuff that he can't measure to his satisfaction. It seems that most of these climate science guys are real good with models, but tend to suck with real test equipment.
Now don't take this in a bad way, but claiming an accuracy of +/- 0.15 Watts per meter squared with a model when the real world test equipment can only give you an accuracy of about +/- 7 Watts per meter square is one damn good model! Sounds almost too good to be true.
While the back radiation term for temperature really sounds important, in my world real accuracy and real uncertainty is important. The right amount of simplification can do wonders.
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