The rejection of science fact and the embrace of science fiction is perhaps best encapsulated by those persons who think manmade climate change is a hoax while believing that chemtrails are real.

First, let’s deal with anthropogenic global warming. I have seen Sean Hannity and others challenge climate change believers on exactly what percentage of global warming it is that humans are responsible for. While not responding directly to that challenge, Brian Dunning penned an excellent piece for Skeptoid which showed how simple observation reveals that average annual global temperature is rising and that human activity is the overwhelming reason why. He noted this can be done without use of “climate models, politics, predictions, economics, or how many scientists agree.”

The key point is that CO₂ levels are rising as the result of human activity. From here, it gets a little more technical, but stay with me. Carbon dating is done by comparing the amounts of carbon-12 and carbon-14 in a sample. When organisms die, carbon-14 decays and no new carbon-14 comes in. This means eventually only carbon-12 remains. Fossil fuels come from plants that died millions of years ago so they have no carbon-14. Hence, the CO₂ produced by burning fossil fuels contains only carbon-12.

The one natural source of carbon-12 is volcanoes and volcanologists measure their output and know that each year, worldwide volcanic activity contributes about 200 million tons of CO₂ to the atmosphere. This accounts for .006 percent of the 29 billion tons of carbon-12 that enters our atmosphere each year. The only source for the other 99.994 percent is fossil fuel burned by humans. So when observers carbon date the CO₂ in the atmosphere, it reveals precisely how much of it comes from people burning fossil fuels. Oceans and plants can only absorb about half of that 29 billion tons, with the rest ending up on our atmosphere, where it remains.

Now we will address how we know that those 14.5 billion tons of carbon-12 is causing an increase in average global temperature. There are five gases that are primarily responsible for the greenhouse effect: CO₂, methane, water vapor, nitrous oxide, and ozone. Through a method called spectroscopy, observers can measure how much of these are present. Earth’s surface is warmed by the sun and our planet emits that same heat back as infrared radiation. When aiming a spectrometer skyward, observers see peaks and valleys in the infrared spectrum and can determine which greenhouse gases are trapping Earth’s radioactive heat. This method provides clear evidence that excess heat energy is being trapped in our atmosphere because of increased CO_2, which we saw earlier is the result of humans burning fossil fuels.

Those who dismiss AGW are denying what scientists are able to see through their analysis of carbon dating and spectroscopy. Meanwhile, some of those same persons say that what is really dangerous for the planet and its inhabitants are strings of fluffy white smoke.

They are convinced that harmless water vapor left in the wake of flying aircraft is a weaponized agent that will do something nefarious, though it’s not agreed on precisely what that is. Speculation includes poisoning, sterilization, mind control, and unleashing tornadoes. Believers will often point to geoengineering, cloud seeding, or attempts to control the weather, all of which have happened, but are unrelated to airplane exhaust. All this was explained in a pair of Washington Post essays by Matthew Cappucci and Dennis Mersereau.

Like the current warming trend, contrails are man-made. They are clouds that form under ordinary environmental conditions and follow the physical processes that occur with any other cloud. In the specific case of contrails, they form when hot, moist aircraft exhaust condenses after coming into contract with extremely cold temperatures in the upper atmosphere. A long, narrow cloud results.    

There is usually little water vapor present because air’s ability to hold moisture wanes as the temperature drops, and temperatures at this altitude are around minus -40 Fahrenheit (which is also -40 Celsius, I’ve always liked that). Cappucci wrote that despite those frigid numbers, water vapor remains a gas or liquid and does not become ice because water must have something to latch onto in order to become an ice crystal. He further explained, “When the airplanes emit aerosols, sulfates, soot, carbon dioxide, hydrocarbons, water vapor, and so on, the particles in its wake can serve as the nuclei for cooled water droplets and vapor to condense and freeze on,” and a contrail is born.

There is variety in the contrail family and some paranoids say these differences distinguish contrails from chemtrails. Believers concede that some airplane exhaust is harmless but insist that at other times airplane emissions represent the deliberate sabotaging of our lungs and minds. As this has zero evidence in reality, there are differing assertions as to which is the key factor that gives away chemtrails. Some say duration determines it, some say thickness, and others go with color. But science explains why all these ideas are mistaken.

Altitude and the air’s wetness determine how long contrails are. If an airplane is flying through wet air, it leaves a contrail; if it is flying in dry air, it does not. Airplanes that appear to be at the same height from ground level may actually be 5,000 feet or more apart in terms of altitude. Chemtrail detectives love to show an airplane leaving little or no contrail, while another plane in the same frame is bellowing out a lengthy cloud, but this is the result of altitude and air conditions, not because government agents are dispatching death from above.

With regard to duration, how long contrails last depends on the humidity level and how favorable the atmosphere is for sustaining them. These are the same factors that help determine whether a day is cloudy or sunny.  

As for their color, the key elements are the contrails’ height and the planet’s curvature (convincing Flat Earth chemtrailers is an especially challenging undertaking). Contrails are dispatched at nearly 40,000 feet and when natural clouds closer to the ground look dark in the waning daylight, contrails will still glow for a few minutes after sundown. Also, when an airplane flies directly away from a setting or rising sun, a contrail may block out much of the sun and this gives the contrail a blackened appearance.

Another reason to discount the chemtrails conspiracy theory relates to an airplane’s travel weight. Mersereau noted that a fully-loaded 747 flying from London to Hong Kong would require almost 60,000 gallons of fuel. That would weigh nearly 200 tons and along with passengers, cargo, and luggage, would leave precious little room for weapons in a mind control program.

As to all this, one Post reader umed, “What a joke. Our government has been involved in weather modification since the 1940s. Do a little research.”

The U.S. government may have made previous attempts at weather modification but there is no connection between that and airplane exhaust. And by research, the reader does not mean retreating to one’s laboratory, employing the Scientific Method, and submitting results for peer review. He is talking about clicking on the YouTube link he provided.