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Tuesday, May 21, 2019

Carbon 12 overload

The Simple Proof of Man-Made Global Warming


I encourage everyone to listen to this episode, or to read and share its transcript online. Today I'm going to talk about some simple factual observations that anyone can make, that unambiguously prove human activity is driving warming of the Earth. I'm not going to mention climate models, politics, predictions, economics, or how many scientists agree or disagree — any of the topics on which there is debate. I'm only going to share a few of the most solid basics, the results of absolute measurements, over which there is no debate. These are the things nobody disagrees with, but so few people understand. Despite its contentious topic, this episode is intended to be — and should be — completely non-controversial.

I am only going to make two points today, and they are to share two of the "smoking guns" by which we know that this is happening. They are simple to understand, and they are based on basic science that everyone should remember from school. They do not depend on models or predictions, but upon simple direct observations. They are that the rising CO2 (carbon dioxide) in the atmosphere is definitely produced by human activity, and that that same CO2 is warming the planet. Nothing in this episode is disputed, or is subject to alternate explanations, but too few people are aware of these facts. So let's begin with:

Proof that the atmosphere's excess CO2 is human generated

You might think that carbon is carbon, and that if we find there's more CO2 in the atmosphere, its source can't easily be proven. But chemistry is a bit more complicated than that; there are different kinds of carbon, as there are of most elements. They're called isotopes. One isotope of carbon is carbon-14. Cosmic rays bombard the Earth at a rate that is more or less constant over time. When they do, they strike atoms in the upper atmosphere, kicking out neutrons. These neutrons then collide with the most common atoms in our atmosphere, nitrogen. This collision kicks a proton out of the nucleus and turns the nitrogen into carbon with two neutrons too many: the unstable and radioactive carbon-14, instead of the normal stable carbon-12.

You've heard of carbon dating; this is done by comparing the relative amounts of carbon-12 and carbon-14 in a sample. Living things, like animals and trees, are in equilibrium with the atmosphere. As they eat and breathe and interact, they contain the same proportions of carbon isotopes as the atmosphere. When they die, that carbon-14 decays over a long time, and since the organism is no longer eating and breathing, no new carbon-14 comes in, and eventually the only carbon remaining is carbon-12 (and some carbon-13). Fossil fuels like oil and natural gas come from plants that died millions of years ago and have no carbon-14 left. The CO2 produced by burning fossil fuels contains only carbon-12.

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