Gyro frequency and Sun: the cause is one and the same
When broadcast first began in 1909, it was primarily in the VLF range which has been shown to stimulate EEP-NOx through the generation of ionospheric plasma turbulence. In the 1920s when AM really took off, the energy sent through the E layer of the ionosphere continued to cause electron precipitation EEP and the production of NOx to deplete the ozone layer in polar regions which increased UV rays and the heating of Greenhouse Gases and a subsequent rise in temperature through the greenhouse effect. This took place up until the mid 40's when television came on with frequencies shown to suppress ionospheric ion acoustic energy flow ~ potentially allowing EEP-NOx to calm.
As the ozone layer repaired it self.. the temperature decreased for five years until the early 50's when the interaction between ozone's depletion and creation found equilibrium.
Energetic particle outflows in the polar regions contribute to density shifts in polar ions and electrons which change the charged currents of particles flowing through solar-terrestrial flux tubes and flux tube morphology. The charge gradients and RF induced heating in the solar wind alters the fast solar wind particle flow and even energetic backscatter in the convective region of the sun. It takes 11-12 years or so for density shifts and cyclotron maser heating of particles to reach the sun. This in turn contributes to sunspots and throws more solar particles back at earth causing SPEs (Solar Proton Event) which further depletes ozone through EEP-NOx. The rise and fall of the sunspot cycle can be seen to follow the same rise and fall in temperature ending in the late 50's just 11 years earlier, because the cause is one and the same.
This gyro energy is observed heating particles (protons) into the solar wind causing back-scatter and a boiling of the solar photosphere.
The Final Rise
As FM came over the airwaves, its energy along with AM (1.5MHz) and Television broadcast increased the electron density in the overall ionosphere. The increase of electron density provides an electrical path allowing the gyro energy a conductive bridge from the E layer to the F layer of the ionosphere where it resumes the generation of ionic plasma turbulence and the EEP-NOx ozone depletion process. Luxembourg Effect (Cross Modulation)
Because we can see the link between ozone depletion and the temperature it narrows it down to broadcast (electron precipitation), CFC's or solar variance. Of these 3 ozone depletion mechanisms only broadcast continues to rise unregulated for it's effects on the environment. And although our global temperature is not much higher than the Medieval Warm Period, because it is man made it is no less dangerous. Unless we stop the root of the cause, it may continue.
The reason why it has caused so much debate is because climate scientists knew little about Transmitter Induced EEP-NOx and the effects of broadcast on the environment. While scientists argue from a perspective they study and know, the complexity of this process crosses scientific disciplines, making it difficult to see how they all fit together.
Why haven't we noticed this before?
Electron precipitation has been observed as a constant flow of energy that trickles down from the ionosphere since the 70's, and has been thought of as an unknown 'natural' ozone depletion mechanism balanced by the Chapman Cycle, but to this day nobody knows for sure what causes electron precipitation. Keep in mind that 'unknown' and 'natural' are two different things, 'natural' implies that we know nature is causing it, while unknown means we have no idea. With the transmitter experiments in the 80's scientists realized that radio waves could stimulate electron precipitation. Because all of our measurements of electron precipitation had been conducted in the thick of radio pollution, which has been nonstop since 1909 when broadcast stations first came over the airwaves, a few scientists began to speculate that broadcast may play a role in anomalous electron precipitation, a phenomena previously thought of as natural. You can 'google' and find lots of scientific research about how radio waves can cause electron precipitation, and you can find lots of research about how electron precipitation can increase atmospheric NOx and deplete ozone, but you find very little that makes the larger connection. The Swedish Institute for Space Physics and other atmospheric physicists have recently raised concerns about the role that global broadcast may have on our climate, but nothing has made it through to the media or the greater scientific community.
So for decades text books have been written and sold as science based its development on the assumption that electron precipitation is ‘natural’ and the assumption that broadcast is not powerful enough to affect the thermal structure of the lower atmosphere. This ‘hiccup’ in scientific knowledge occurred because the dissemination of knowledge is slow between disciplines on a global scale, due to the process of the scientific community, where funding is competitive and political while research is accumulated behind paywalls. Since the beginning of time new and great ideas have been cast aside for the familiar. Great minds like Nicola Tesla who gave us electricity or Galileo who said that the earth revolves around the sun were brilliant people who were persecuted for being ahead of their time. One would think the scientific community would see a good or promising idea and latch onto it, but often the opposite happens -- because it upsets careers or it competes with the interests of others. Scientists tend to know their niches but not make connections outside them and the proprietary nature of knowledge through funding slows interdisciplinary collaboration and realization. It takes time and money to create and replace text books and train the teachers of tomorrow. This does not discount good verifiable scientists and projects. After all we are all learning here and we don’t know everything, these things take time.