Dana, what is the 'apparent paradox' Hansen is referring to?

Question

1.6 W/m2 compared to 0.12 W/m2 is NOT a paradox - what is the paradox? 1.6 W/m2 compared to.....WHAT?

Answer 1

Your fishtank example isn't correct physically.  Below is a correct physical system, with a ballpark estimate of the true temperature rise from an increase in radiative forcing of 1.6 W/m^2.  

Take a 1-m by 1-m by 1-m tank that is well-mixed, perfectly insulated, and covered with a special cover that prevents evaporation and convective heat loss from the surface.  The only way this tank can lose heat is by longwave radiative cooling, which oddly, is the only way the Earth can lose energy, since there is no mass loss to space that would support off-planet latent heat transfer or convective heat transfer.  Now, assume that tank is humming along taking in 350 W of shortwave radiation and radiating back out 350 W of longwave radiation.  That means the tank is at 280.3 K.  Now all of a sudden you reflect back onto the tank 1.6 W of the outgoing longwave flux.  That means that the tank now has to radiate the 350 W of shortwave energy *and* the 1.6 W of longwave.  This will cause the tank temperature to rise to 280.6 K, so the temperature will rise by 0.3 K, which is fairly consistent with the temperature rise we have seen globally over the last 25 years or so.  

Note that this number is an underestimate because the amount of longwave coming back in the real system depends on the upwelling longwave flux.  More upwelling longwave means more downwelling longwave.  So the radiative forcing from CO2 of 1.6 W/m^2 actually takes more than a  0.3 K rise to offset.  Of course, the 1.6 W/m^2 from the IPCC has this effect built into it, my simple example above doesn't.  

Finally, and most importantly, studies of paleo climate have demonstrated that a net increase in global mean temperature of a few tenths of a degree Kelvin is *HUGE* in terms of affecting climate.  There is simply no other way around this issue unless you want to argue the physics in the example above is wrong, which it isn't.  This is why I claim that climate skeptics would do better to just admit they don't want to inconvenience themselves by reducing energy use, rather than argue that CO2 isn't a problem as far as climate is concerned.  The latter tact makes them look intellectually dishonest and lazy, whereas the former would just make them look lazy.

edit:  Your depth objection is irrelevant.  Depth of the water column only affects how long the system would take to achieve equilibrium, not the final equilibrium temperature.  As for the rest, it's meaningless technical obfuscation.  The underlying physics is very simple, if you put 1.6 W/m^2 into a system at radiative equilibrium at a temperature of around 280 K, the new radiative equilibrium temperature is approximately 0.3 K higher.  You can argue whether or not other mechanisms will help to radiate that 1.6 W/m^2 to space, but it does not change the fundamental fact that 1.6 W/m^2 *will* make a difference to mean temperature, and that climate is exquisitely sensitive to temperature (really, it's sensitive to the radiative forcing but it's perhaps easier to think of it in terms of temperature).

Answer 2

I only read the first page but the paradox seems to be that human contribution to global warming is insignificant compared to the size and vastness of the earth it doesnt seem possible that we could change the enviroment  

Answer 3

This is one reason latent heat is so important and shouldn't be down played in modeling. It would depend totally on the onset values of the water. Thus T^4 could be determined with e being a constant and not a variable. Sigma is defined. Hence the average temp of water is dependent on volume and ambient temp. Of course they have a average ocean temp with a factor of 6C variance. But no one  has bother to mention onset values. Then of course, past the 500ft mark the sun has no value.

Answer 4

I thought I answered this in your other question.

Essentially the apparent paradox is that 1.6 W/m^2 doesn't sound like a lot - as Hansen put it, a couple of x-mas light bulbs over each square meter of the Earth's surface.  But as it turns out, seemingly small forcings acting constantly over long periods of time can have large effects.

*edit1*

"Take a 1.6 W/m2 light bulb and try to heat some water. It just doesn't work, even if you wait 30 years or 100. What am I missing?"

Go ahead and try it.  I guarantee you it will heat the water.

"So we've established that 1.6 W/m2 is human. How much heat strikes the Earth and is absorbed by the sun & atmosphere? 492 W/m2."

As I pointed out in your other question, you're comparing apples (i.e. incoming solar radiation) and oranges (anthropogenic radiative forcing).  Incoming solar radiation is 168 W/m^2, but the solar radiative forcing is 0.12 W/m^2.  It's radiative forcing (imbalance of incoming and outgoing radiation) that causes the planet to warm.

*edit2*

First off, the planet isn't entirely water.  The issue you're having is exactly why the land warms faster than the ocean.

Secondly, you're missing the point that you can't compare numbers that measure different things.  The energy coming from the Sun and atmosphere - first off, where do you think the energy from the atmosphere comes from?  

Secondly, if the same amount of energy is incoming and outgoing, the planet will remain at a constant temperature (and radiative forcing will be zero).

If you want to compare the 1.6 W/m^2 to something, compare it to the 0.12 W/m^2 solar radiative forcing.

Look - I assume you don't deny that the planet has warmed.  The reason is because of this energy imbalance.  The greatest cause of that energy imbalance is CO2.  It's that simple.

Answer 5

Look Hansen's paradox is not complicated. He measures baseline per heat element in the singular. That is to say that one human produces a temperature 98.6 degrees, of course this skews his numbers to a favorable outcome to support his claim. What he does not take in to consideration, is the mechanical  heat index produced by human consumption again skewing the math to favor his claim.

There are easy ways to disprove Hansen's. Think easy bake oven, a child's toy that cook that bakes a cake using the heat energy from a light bulb.

Take ten people put them in a 5x5 box they will all radiate 98.6 degrees the room temp or ambient temp is 72 degrees...prime temperature for human body temp regulation...you begin to perspire above 72...over time they will heat the ambient air to 98.6 from the radiant heat loss form the bodies unless you stop the radiant heat loss you can not stop the temperature increase...this is global warming... our box is just bigger and we are adding more and more heat to the box. Atmospheric temperatures have been measurably increasing...granted we may be going into an ice age and the earth itself has a lot to do with it...but so do we...The last age atmospheric temperatures were not nearly at the levels they are today preceding the ice age. Furthering the evidence of human impact.

Hansen's paradox measuring at a single element and not taking in account any side effect caused by the element is ludicrous.

When folks argue Hansen's paradox supports anti global warming platforms I wonder why really motivates them to spit out such drivel.

Answer 6

OK, YOU ARE ASKING A ***** THAT WANTS SCIENTIFIC, PEER REVIEWED STUDIES THAT PROVE THAT THE SUN WARMS US...  I THINK HE NEEDS A 72 HOLD