Global Warming

No one who takes climate change seriously disputes the role greenhouse gases (GHG – of which CO2 is one) play in contributing to ambient global temperature of the atmosphere (or, to be completely accurate the lowest level of the atmosphere called the troposphere). Rether, the scientific debate centers on the extent to which the contribution of human-produced CO2 (Anthropogenic CO2) in the atmosphere lead to global warming specifically and climate change generally. That atmospheric CO2 influences global warming is inarguable.

But let’s make sure that before you go any further we agree on two points: first, the basic theory behind Global Warming and second, the concentration of GHGs in the atmosphere (described here1)Out of all the gases that comprise the atmosphere, only two percent are greenhouse gases (GHG). In fact, the atmosphere consists largely of Nitrogen and Oxygen totaling about 98% of atmospheric gases. The remaining 2% are the GHGs. Just to put this in perspective, for every 1 million molecules in the atmosphere, 980,000 are either Nitrogen or Oxygen and the rest, about 20,000 molecules are GHGs.

Now, it turns out that only 3.6% of those 20,000 GHG molecules are CO2 molecules – the rest being water vapor, methane, and others. In other words, for every 1 million molecules in the atmosphere about 720 are CO2 molecules.

However, about 96.6% of atmospheric CO2 comes from non-human sources (e.g., plant respiration among others). Anthropogenic CO2, in fact, constitutes only about 3.4% of these 720 CO2 molecules in the atmosphere are man-caused. Or, doing the math we see that only 25 molecules out of every 1 million atmospheric molecules are CO2 molecules contributed by human activity.).

Both sides of the Anthropogenic Global Warming (AGW) debate assume3)This assumption has its skeptics who point to the observation that average climate temperatures cycle between hot and cold periods suggesting that there is a natural damping effect that modulates temperature extremes on both sides of the average. Indeed, a good argument can be advanced that the cycle of CO2 transfer between terrestrial sources and the atmosphere is the modulator of this cycle. In other words, if we observe the average 1000 year global temperature to be warming, we may be on the upswing of a normal cycle – ditto for global cooling. that the Earth naturally maintains a constant average temperature arising from (a) the amount of solar energy absorbed by the Planet and its atmosphere and (b) the amount of heat (InfraRed Radiation, IRR) emitted. In other words, the balance equation is

(Solar Heat Input) = (Heat Output as IRR)

Greenhouse gases (GHGs) in the atmosphere (mostly water vapor) have substantial influence over how much IR energy the Earth loses over a specific period of time. Since GHGs absorb emitted energy, an increase in GHGs will cause the global temperature to rise. Greenhouse gases act like a blanket and trap warmth beneath it.

Global warming theory holds that as the temperature rises the rate of heat emitted to outer space increases until the emitted IRR once again equals the amount of absorbed sunlight. That is, the Earth must increase its temperature until global energy balance is once again restored. This is the basic explanation of Global Warming theory.

Now, you might be surprised to learn that the amount of warming directly caused by CO2 is very minimal2)Minimal largely because the concentration of man-made CO2 is vanishingly small. For example, the ratio of man-made CO2 molecules to the total number of atmospheric molecules is (25/1,000,000). See footnote above.. For example, if all the other variables are held constant, i.e., no other changes in the climate system, a doubling of the atmospheric CO2 concentration would cause slightly less than 1 degree C of surface warming. This is NOT a controversial statement…it is well understood by climate scientists on both sides of the debate (as of 2008, we were about 40% to 45% of the way toward a doubling of atmospheric CO2).

Now it is true that small amounts of CO2 can affect the balance in the same way that a slight vibration might cause a quarter balanced on its edge to tip over. This is the assumption behind the alarmism of climate change advocacy. It turns out that the computer models  that show catastrophic results when a small increase in CO2 concentration is introduced discount (or hold constant) other variables to which the balance equation is sensitive. Modeled this way, they can show that a small increase in CO2 caused by human activity can catastrophically ‘tip’ the balance of climate temperature and that all other variables are held constant.

It all comes down to the question of sensitivity and to what variables is the balance equation most sensitive. So, let’s look at the idea of sensitivity: nothing in the climate ecology stays the same! For instance, clouds, water vapor, and precipitation systems can all be expected to respond to the warming tendency in some way, which could either amplify or reduce the man made warming. The effect of these variables, of which man made CO2 is one, are called “feedbacks,” and the sum of all the feedbacks in the climate system determines what is called ‘climate sensitivity’. Negative feedbacks (low climate sensitivity) would mean that manmade global warming might not even be measurable, lost in the noise of natural climate variability. But if feedbacks are sufficiently positive (high climate sensitivity), then manmade global warming could be catastrophic.

Obviously, knowing the sensitivities of these variables in the climate system is critical and is currently one of the hot research areas of climate change. Sadly, this area of research is largely ignored by the lay press in favor of the alarmist  catastrophe advocates which get people excited and increase subscriptions, advertising revenue, and clicks (i.e., equivalent to the principle of “if it bleeds, it leads”).

Among the best research on the nature of climate sensitivity is Robert Spencer’s work on what is termed the Pacific Decadal Oscillation (PDO). Scientists who are (disparagingly referred to as “climate deniers”) working in this area are coming to a conclusion that the climate is largely insensitive.  Spencer, among others, has shown, for example, that the early satellite observations of natural climate variability had potentially large errors obscured and confused how these variables effected the climate. More specifically, these errors led to the illusion of a sensitive climate system. Indeed, more recent satellite observations when carefully and properly interpreted has led to the conclusion that the climate system is largely insensitive to perturbation. He theorizes that the PDO has, among its many behaviors, the ability to dampen these perturbations and, in the case of extra CO2 pumped into the system – man made or otherwise – to absorb it.

 

Now, it turns out that only 3.6% of those 20,000 GHG molecules are CO2 molecules – the rest being water vapor, methane, and others. In other words, for every 1 million molecules in the atmosphere about 720 are CO2 molecules.

 

However, about 96.6% of atmospheric CO2 comes from non-human sources (e.g., plant respiration among others). Anthropogenic CO2, in fact, constitutes only about 3.4% of these 720 CO2 molecules in the atmosphere are man-caused. Or, doing the math we see that only 25 molecules out of every 1 million atmospheric molecules are CO2 molecules contributed by human activity.

 

 

Footnotes   [ + ]

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