Marine Watchdogs
6 min readOct 3


What started as an investigation into anthropogenic cloud formation ended with revelations I couldn’t possibly have guessed at.

Dave Dahl

First I should tell you how I came by this information. As a technical content producer, research is the biggest part of my job, and as a skeptic, I avoid anecdotes, observations without verifiable data, and most witness testimony.

So when I looked into persistent contrail clouds, I began with secondary research from credible sources such as NASA, NOAA and so on. After that, I spoke with scientist friends, teachers, weather modification pilots, meteorologists and climatologists.

Then I called the Science Director at NASA. He answered. He directed most of my questions to a cloud-aerosol interaction specialist there who filled me in on some of NASA’s atmospheric research and satellite instruments.

I studied the clouds in Europe, Asia and Micronesia as well as the east and west coasts of the US, hired helicopters to determine exact altitudes of clouds and took time-lapse videos of natural and artificial clouds forming.

Clouds over the Rock Islands of Palau at 7,500 feet

But what I found in the US Library of Congress in the first couple weeks is what intrigued me enough to continue: the beginning of our concerns about human activity directly affecting the climate.

In the 1960s, the Department of Transportation noticed that jet aircraft, which had quickly become a widely popular mode of transport, were affecting the weather.

They realized that jet airplanes were creating clouds in such abundance that the consistent change in cloud cover would have greater climate implications. They called it “inadvertent climate variation.”

It was no longer an obscure, remote theory. They were witnessing it.

In a 1974 report to the US President and Congress, the US Department of Transportation wrote that “inadvertent climate variation is of worldwide concern.”

That year an enormous study of the atmosphere called GARP was launched after several years of experiment design and planning. The GARP study involved 70 countries, 40 vessels and 13 aircraft as well as satellites, buoys and land stations.

Following that study, in 1978, Congress declared climate variation an issue of National Security.

This origin story corresponded with NASA’s primer Understanding the Importance of Clouds, which states on the first page that “even small changes in the abundance or location of clouds could change the climate more than the anticipated changes caused by greenhouse gases.”

So it followed to ask, How can we alter the abundance and location of clouds? And it turns out, we are; human-caused cloud cover is in fact significant, and is a major factor in anthropogenic climate alterationmaybe even the primary factor.

Like natural clouds, human-created clouds affect the weather.

To begin with, jet aircraft have some of the biggest engines humans produce on a large scale, and they’re the only machines that actually inject CO2 directly into the upper atmosphere, destroying ozone via super-heated steam from their exhaust.

But there’s a lot more to the story of how aircraft affect the climate.

We talk about CO2, but we rarely discuss its counterpart, H2O. When we burn fuel — hydrocarbons — there are two main resulting byproducts: CO2 and H2O. For every gallon of jet fuel used, a gallon of water is created as a byproduct, in the form of invisible vapor.

But the water vapor in jet contrails is different from water vapor as we normally think of it down here in the troposphere. This water is created at the molecular level at thousands of degrees Fahrenheit and blasted as a gas into a sub-zero environment at 500 miles per hour, instantly becoming a thick cloud of microscopic ice crystals.

In the low-pressure environment, the wake of frozen H2O gas expands rapidly, and in the warmer air behind the exhaust emissions, BOTH gases — the frozen CO2 and H2O — continue to rise and mix with atmosphere indefinitely.

Natural low clouds in California
High clouds created by aircraft in California

Whether contrails persist and spawn cloud cover depend on a number of other factors (but, visible or not, water is always produced when aircraft fly).

First, in general jet airplanes make contrails on ascent, and once they reach 20,000 feet or higher, depending on where on Earth it takes off from (since the stratosphere is lower toward Earth’s poles), it tends to disappear. That’s because when it reaches cruising altitude, a jet uses much less fuel than it does on ascent, and there’s less moisture (ice crystal saturation) and less condensation nuclei at altitudes above 30,000 feet.

The level of humidity or ice crystal saturation is a big factor as well. In warm, dry air, contrails evaporate quickly. On the other hand, if the humidity is high at contrail-forming altitudes, contrail clouds can persist and form vast areas of cloud cover, the result of many planes traveling the same routes, making expanding lines across the sky.

Much of the high-altitude “cirrus cloud” cover we see is created by aircraft

Today, we’re using about 60 billion gallons of jet fuel per year, which produces 60 billion gallons (almost half a trillion pounds) of frozen, gaseous water vapor that expands in the frozen (but relatively warmer) air in the wake of the contrail, preventing condensation. Unaffected by gravity at high altitude, the H2O remains in a gaseous state and, like the CO2, it stays in the atmosphere indefinitely.

But there’s more.

Most scientists I’ve spoken with, including meteorologists and climatologists, are unaware that high-altitude weather modification programs have been ongoing around the globe for decades, including in most western US states and in most countries that need more water… which, as groundwater sources are becoming depleted worldwide, is most counties.

The programs are intended for precipitation enhancement and use fleets of cloud-seeding aircraft burning silver iodide flares to inject cloud condensation nuclei into the upper atmosphere, typically at around 20,000 feet, sometimes higher. (We do this right here in Santa Barbara County and all over California.)

To burn on the wings of aircraft in high winds and sub-zero temperatures, silver iodide cloud seeding flares contain metals like aluminum and strontium.

These ongoing programs, which coincidentally began in the 1960s with the invention of silver iodide cloud seeding, are different from proposed climate engineering solutions like solar radiation management, but our worldwide attempts to produce more precipitation with aircraft have amounted to inadvertent geo-engineering by facilitating cloud production, which has climate consequences.

Clouds not only create shade in the daytime, causing lower temperatures and pressure differentials that alter wind patterns, they also insulate the Earth at night, preventing heat from escaping into space. (I have yet to find a study that considers the nighttime insulative effect of overlapping cloud layers, when high clouds are created by aircraft above lower natural clouds.)

While I can’t say for sure who first said what about the climate, the earliest book I’ve found on the subject, Inadvertent Climate Variation, was published by MIT in 1971, a report led by Caroll L. Wilson and William H. Matthews on a research project called The Study of Man’s Impact on Climate.

In the future, some scientist with enough renown, or maybe one with nothing to lose, will take on these new anthropogenic phenomena: the trillions of cubic feet of frozen H2O gas added to the low-pressure environment of the upper atmosphere every year, and the impact of our ongoing worldwide cloud-seeding activity on the climate, and on the air, soil and water below.

(More on weather modification at artificialclouds.com)