THE CARBON CYCLE AND LeChatelier’s Principle

Here is an incomplete version of the carbon cycle.

What does the video skip over? A type of rock. Limestone. What is limestone?

Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO₃) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.http://geology.com/rocks/limestone.shtml

How are carbonate rocks formed?

1. Carbon dioxide is removed from the atmosphere by dissolving in water and forming carbonic acid

CO₂ + H₂O -> H₂CO₃ (carbonic acid)

2. Carbonic acid is used to weather rocks, yielding bicarbonate ions, other ions, and clays

H₂CO₃ + H₂O + silicate minerals -> HCO₃^– + cations (Ca⁺⁺, Fe⁺⁺, Na⁺, etc.) + clays

3. Calcium carbonate is precipitated from calcium and bicarbonate ions in seawater by marine organisms like coral

Ca⁺⁺ + 2HCO₃^– -> CaCO₃ + CO₂ + H₂O

the carbon is now stored on the seafloor in layers of limestone. (from here)

What is the point? When we listen to the environmentalists, we get the impression that once we burn fossil fuels the CO₂ that results is stuck in the atmosphere. That is not true. Natural processes already exist for removing CO₂ from the atmosphere. What should concern us is these three problems:

• How fast can the oceans remove CO₂ from the atmosphere? That is, do we have the capacity to upset the earth’s CO₂ balance sufficiently to cause harm? To answer that question, we need to consider Le Chatelier’s Principle. Le Chatelier’s Principle can be stated as follows:
  

  A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.

  What does that mean with respect to burning fossil fuels? Because we produce more CO₂, the oceans and other carbon sinks (like green plants) absorb more CO₂ from the atmosphere.

  Because of the role of CO2 in climate, feedbacks in the carbon cycle act to maintain global temperatures within certain bounds so that the climate never gets too hot or too cold to support life on Earth. The process is a large-scale example of LeChatelier’s Principle. This chemical principle states that if a reaction at equilibrium is perturbed by the addition or removal of a product or reactant, the reaction will adjust so as to attempt to bring that chemical species back to its original concentration. For example, as carbonic acid is removed from solution by weathering of rocks, the reaction will adjust by producing more carbonic acid. And since the dissolved CO2 is in equilibrium with atmospheric CO2, more CO2 is removed from the atmosphere to replace that removed from solution by weathering. (from here)

  Thus, the issue is the responsiveness of the processes that maintain the CO₂ in the atmosphere at the desired equilibrium. Since we are just beginning to understand those processes, we don’t exactly know how responsive those processes might be. All we can say is that so far the doomsayers are exaggerating.  Burning fossil fuels doesn’t seem to have much effect on the world’s climate.

• How do we remove the substances from fossil fuels that do form pollutants when burned? Smog is what results when we fail in our efforts to clean up what comes out of a car’s tailpipe. Since coal contains substances like sulfur and mercury, burning it can be problematic. Sulfur forms a highly corrosive acid. Mercury poisoning is called the mad hatter’s disease.
• What do we use for fuel when fossil fuels become to costly to get out the ground? Currently, we are still finding less expensive ways to extract fossil fuels from the earth. Thus, we are using fossil fuels from sources that at one time would have been considered too expensive to use. Thus, fossil fuels remain inexpensive. Can that situation last forever? No.

How do we decide what we should do? We must remember that we make decisions based upon our understanding of the information available to us. Currently, our government provides most of our educational instruction, and our government also provides most of the information we have with respect to Global Warming. Is that a good situation? Of course not.

There is no such thing as a perfectly objective person. So there is no such thing as a perfectly objective teacher or scientist. Therefore, if we want to make an objective decision, we must consider information from multiple sources, that is, information on the same subject that comes from different people with different biases. We need a marketplace of ideas. Unfortunately, because politicians run both our education system and fund most of the research on Global Warming, when it comes to this subject we do not have a marketplace of ideas. What we have is a government-run monopoly that presents only one point-of-view.

Other References

• Limestone (www.eoearth.org)
• Le Chatelier’s Principle: The Carbon Cycle and the climate (wiki.chemprime.chemeddl.org)
• Climate change feedback (en.wikipedia.org)
• The Slow Carbon Cycle (earthobservatory.nasa.gov)
• It’s official: 2014 was the hottest year in recorded history (www.washingtonpost.com)