"Oh, please. We know that temperatures have been generally rising for three centuries. So … where will we find the highest temperatures? Oh, the most recent years? Gosh, that’s shocking news … not.
If you think that is significant, think about it a bit more deeply."
This response by Eschenbach is of course nonsense. He's trying to suggest that the temperature rise is entirely natural, but of course it isn't. Yes, climate scientists have to distinguish between what is natural climate variation and what is man-made climate change, but the evidence for human-caused climate change is incontrovertible.
Next we have someone by the name of Tony Mcleod, who posted this interesting graph from the US National Oceanic and Atmospheric Administration (NOAA):
"Willis, you should not bother to reply to people who have no qualifications and no understanding of heat and mass transfer, or thermodynamics"
I admit I am not a scientist, but I do listen to them actually. As a result, I copied this into a word document from Skeptical Science, in response to the claim that the 2nd Law of Thermodynamics contradicts global warming:
"The sun warms the Earth. The Earth and its atmosphere radiate heat away into space. They radiate most of the heat that is received from the sun, so the average temperature of the Earth stays more or less constant. Greenhouse gases trap some of the escaping heat closer to the Earth's surface, making it harder for it to shed that heat, so the Earth warms up in order to radiate the heat more effectively. So the greenhouse gases make the Earth warmer - like a blanket conserving body heat - and voila, you have global warming.
The second law of thermodynamics has been stated in many ways. For us, Rudolf Clausius said it best:
"Heat generally cannot flow spontaneously from a material at lower temperature to a material at higher temperature."
So if you put something hot next to something cold, the hot thing won't get hotter, and the cold thing won't get colder. That's so obvious that it hardly needs a scientist to say it, we know this from our daily lives. If you put an ice-cube into your drink, the drink doesn't boil!
The skeptic tells us that, because the air, including the greenhouse gasses, is cooler than the surface of the Earth, it cannot warm the Earth. If it did, they say, that means heat would have to flow from cold to hot, in apparent violation of the second law of thermodynamics.
The skeptic is ignoring the fact that the Earth is being warmed by the sun, which makes all the difference."
Michael Hammer also has this to say on Jo Nova's blog:
"The 2nd Law of Thermodynamics applies to net flows of heat, not to each individual photon, and it does not prevent some heat flowing from a cooler body to a warm one.
Imagine three blocks of metal side by side. They are 11°C, 10°C, and 9°C. Think about what happens to the photons coming off the atoms in the middle of the medium temperature block between the other two. If heat never flows from cooler blocks to warmer blocks, all those photons have to go “right“, and not ever go “left”, because they “know” that way is towards a cooler block? (How would they?!)
The photons go both ways (actually every way, in 3D). There are more coming from the 11°C block to the 10°C block, sure, but the the 10°C block is sending ‘em back to the 11°C block too. So heat is flowing from cold to hot. It happens all the time. Net heat is flowing always hot to cold. But some heat is going the other way, every day, everywhere, bar possibly a black hole."
Jo Nova herself has this to add:
"People are being caught by semantics. Technically, strictly, greenhouse gases don’t “warm” the planet (as in, they don’t supply additional heat energy), but they slow the cooling, which for all pragmatic purposes leaves the planet warmer that it would have been without them. It’s a bit like saying a blanket doesn’t warm you in bed. Sure, it’s got no internal heat source, and it won’t add any heat energy that you didn’t already have, but you sure feel cold without one. – Jo"
Michael goes on:
"I have lost count of the number of people claiming that global warming is impossible because the atmosphere is colder than the surface and thus cannot return heat to the surface since that would contravene the second law of thermodynamics. This is wrong and is based on an incorrect interpretation of the second law. The second law does not say a cold object cannot pass heat to a warmer object, it states that NET heat flow is always from warmer to colder."
"Imagine you are standing outside on a cold winters night. It’s really cold and you are soon chilled to the bone so you step inside.
Inside it’s a pleasant 20°C and almost immediately you feel warmer. But you are at 37°C and the room is 17°C cooler at 20°C how can it warm you, the second law of thermodynamics forbids it! No it doesn’t. When you were outside, your body was radiating energy to space but because the environment was so cold there was very little radiating back to you so the net loss was substantial.
When you step inside your body is still radiating exactly the same amount of energy (remember the amount radiated depends only on the temperature and emissivity) however now the warmer walls of the room radiate more energy back to you than did the cold outside. Since the walls are colder than you are you still radiate more energy than you receive (heat flow is still from you to the room) but the difference between what you radiate and what you receive is less. You lose less net energy when inside than when outside so you feel warmer inside the room and it is easy to feel the room is warming you. In fact it is more accurate to say the room cools you less than did the outside.
Exactly the same situation exists with respect to Earth’s surface. Without the green house gases in the atmosphere the surface would be radiating directly to outer space which is extremely cold (-269°C). The green house gases prevent some of that radiation to space and thus keep the surface warmer than it would otherwise be. They do not do this by reducing the amount of energy the surface emits – doing that would entail changing the surface emissivity. Instead they radiate energy back onto the surface so that the net energy loss is reduced."
I am not a scientist and yet even I can get this. So don't accuse me of having no understanding of thermodynamics!!!