Guest Post by Willis Eschenbach
Let me start with the standard explanation of why the earth warms when greenhouse gases (“GHGs”, e.g. water vapor, CO2, methane, etc.) increase. This is from NASA:
When averaged over the course of a year, the amount of incoming solar radiation received from the sun has balanced the amount of outgoing energy emitted from Earth. This equilibrium is called Earth’s energy or radiation balance. Relatively small changes in the amounts of greenhouse gases in Earth’s atmosphere can greatly alter that balance between incoming and outgoing radiation. Earth then warms or cools in order to restore the radiative balance at the top of the atmosphere.
That explanation is clean and clear. When greenhouse gases reduce the amount of outgoing radiation, the earth’s surface has to warm up and radiate more, until the balance is restored.
According to NASA it’s quite clear and obvious—when CO2 increases, simple physics requires that the surface temperature increases to keep the radiation balance at the top of the atmosphere.
So, what’s not to like?
To explain what’s not to like, let me provide the simplest possible energy balance model of the earth. The values are all approximate.
Figure 1. Approximate energy balance of the planet. All values are in watts per meter squared (W/m2).
There are three layers in the model—the lowest part of the stratosphere; the troposphere; and the surface. Note that all three layers are balanced, in that the amount that is radiated by each layer is equal to the amount that is absorbed. In addition, the system as a whole is balanced—237 W/m2 is absorbed by the system, and 237 W/m2 is radiated back out to space.
Now, recall the NASA claim that if GHGs increase and absorb more upwelling radiation, that the “Earth then warms or cools in order to restore the radiative balance at the top of the atmosphere.”
How large a change in the radiation balance are we talking about? Well, if we use the figures of the Intergovernmental Panel on Climate Change (IPCC), since the year 1958 when we started measuring CO2, the reduction in outgoing longwave radiation due to increased CO2 is about 1.5 W/m2. This is a change of a bit more than half of one percent of total outgoing radiation. Or to look at it another way, it’s an imbalance that is increasing at the rate of about two-hundredths of one watt per square meter per year … very, very small, in other words.
So let me ask you. Looking at Figure 1 above, is the warming of the surface the only way that the outgoing radiation at the top of the atmosphere (TOA) can be increased by about half a percent per half century to restore the overall balance?
Obviously, and totally contrary to NASA’s claim, surface warming is NOT the only way to restore the top-of-atmosphere radiation balance. Some of the other ways are:
• Decrease the incoming radiation. This happens by means of changes in the amount, composition, albedo, thickness, time of emergence, and/or nature of the clouds. It also happens over the ocean, from the ocean albedo changing due to winds causing breaking waves, spume, and foam. These are all white and reflect much more sunlight than does a calm ocean surface.
• Increase the amount of solar radiation absorbed by the atmosphere. This happens by means of changes in the amount of atmospheric water vapor, or by changes in the clouds.
• Increase the amount of latent heat removed from the surface via evaporation of water. This happens by changes in the wind, since evaporation is inter alia a linear function of the wind speed. It also happens by changes in the number of thunderstorms, which increase local evaporation due to storm-generated winds. It also happens due to increasing ocean water surface area due to spray, as well as due to the increased surface area of waves compared to smooth water.
• Increase the amount of sensible heat removed from the surface. This is also a function of the wind, since the sensible heat transfer increases as a linear function of wind speed.
• Increase the amount of surface energy moved high into the troposphere inside thunderstorm towers. These towers circumvent greenhouse gases in two ways. First, heat from the surface is moved into the bases of the thunderstorms as latent heat of water vapor, which doesn’t interact with the greenhouse gases. Then when the water vapor condenses, the heat is released. But it travels vertically inside the cloud tower, where it is not free to interact with the surrounding greenhouse gases. At the end of the vertical movement, the energy is released far above the surface, where there are far fewer greenhouse gases to absorb it.
• Increase the amount of surface upwelling radiation that makes it directly to space. This happens in the areas around and between the thunderstorms. These areas are composed of dry descending air which has been emitted at the top of the thunderstorms after having most of the water condensed out. Because water vapor is the major greenhouse gas, this lets much more surface energy go straight to space.
• Increase the amount of energy moved from the tropics to the poles. This is a huge amount of energy, about 10% of the total solar energy entering the system. Because the poles are much drier and colder than the tropics, much more of the outgoing radiation from the surface goes straight to space. When more energy is moved polewards, more radiation escapes to space.
Any one of these phenomena is certainly capable of changing outgoing TOA radiation by half a percent in half a century.
Let me summarize:
- There really is a very poorly-named “greenhouse effect”, which has nothing to do with greenhouses. It’s the main reason why the earth is not as cold as the moon.
- When greenhouse gases increase, the amount of outgoing top-of-atmosphere radiation does decrease.
- The theoretical imbalance over the last sixty years due to increasing CO2 is about 1.5 W/m2, or about half a percent of the outgoing radiation. Per year, it’s an annual imbalance increase of 0.02 W/m2, an amount far too small to measure.
- Unlike what NASA and other mainstream scientists endlessly claim, there are many more ways other than surface warming for this imbalance to be restored.
- In general, we do NOT have measurements of the various other ways of restoring the balance that are anywhere near accurate enough to tell us how much of each of these phenomena contribute to the 0.02 W/m2 change which is annually necessary to restore the balance.
The important takeaway from all of this is that there is no physics-based requirement that surface temperatures perforce must change when the level of CO2 and other greenhouse gases increases or decreases. The surface temperature may indeed change to restore the TOA radiation balance, but contrary to the endless claims of the alarmists, there is no physics that requires that it does so.
There is a further problem, which is that the amount we don’t know about the climate far exceeds the amount we do know. For example, here are 2,000 years of Northern Hemisphere temperatures.
Figure 2. The temperature history of the extra-tropical northern hemisphere from 30°N to 90°N. These have about an 80% correlation with global temperatures.
Here are questions that we don’t know the answers to about the thermal history shown in Figure 2:
- Why did the “Roman Warm Period” end around 150 AD and the world start cooling? Why did it not just stay warm?
- Why did the warmth end in 150 AD and not 50 AD or 300 AD?
- Why did the world keep cooling, in fits and starts, until about 550 AD?
- Why did the cooling stop in 550 AD, and not 350 AD or 750 AD?
- Why did the world warm from there, in fits and starts, until the peak of the Medieval Warm Period in the year 1000 AD?
- Why was the peak not in 800 AD or 1200 AD?
- What started the cooling from there to the depth of the Little Ice Age in 1700 AD?
- Why did the cooling end in 1700 AD, not in 1500 AD or 1900 AD?
- Why didn’t the cooling continue until we went into a true Ice Age, as the Milankovich cycles would suggest?
- What made it start warming again in 1700 AD, instead of just staying at the same cooler temperature?
- Why has the warming continued, again in fits and starts, for three centuries since 1700 AD to the present? (Protip—we know that the first two centuries of warming were NOT caused by CO2 increases.)
Given all of that, the idea that we understand the climate well enough to claim that we can predict the future climate a century from now based solely on projected CO2 levels is … well … let me call it insanely optimistic and let it go at that. As shown above, the system is far from as simple as it is claimed. The computer models are far too crude to capture all the complexities. And most of all, we simply do not understand enough about what natural processes made the past temperatures go up and down to stand a chance of predicting the future temperatures.
Sadly, despite all of that, a horde of obsessed folks, both scientists and laypeople, are insisting that based on nothing more than their inchoate fears of some imaginary future Thermageddon, we totally throw out a very successful energy source that has freed humans for the first time in history from lives of endless want and hunger, and replace that proven energy source with untested, unreliable, intermittent energy sources …
And they are still doing this despite the fact that we’ve been warned every year for half a century that the horrible Thermageddon is only a decade or two away. How many failed, cratered predictions will it take for people to notice that the underlying theory isn’t working?
This is madness. What we need to do is to continue to do what we’ve done so successfully in the past—use our proven, reliable energy sources to work to insulate and protect people from the endless, inevitable vagaries of the weather.
That is the no-regrets option. That way, whether or not CO2 turns out to be the secret knob controlling the temperature, we’ll be far less at risk from storms, floods, droughts, and all of the weather phenomena that have been killing people for millennia.
My very best to everyone,
Keeping Things On Track: I am asking that you stick to the topic of the thread, which is the question of what can change the TOA radiation balance. In particular, if you think that there is no downwards radiation from the atmosphere to the earth, or if you claim that radiation from the atmosphere cannot leave the earth warmer than it would be if there were no radiation from the atmosphere, TAKE THAT ARGUMENT SOMEWHERE ELSE. I am NOT interested in getting side-tractored into debating that question on this thread, and I will assuredly snip it if you try. So save yourself the heartache of watching your genius argument disappear into the ether. There are lots of places on the web where you can debate that question to your heart’s content. This is not one of them. And don’t whine if you try it and get snipped. You’ve been warned, it’s on your head, not mine.
My Usual Request: I can defend my own words and I’m happy to do so. I cannot defend your interpretation of my words. So please, to avoid misunderstandings, quote the exact words that you are discussing.