Radio Waves Can Signal Climate Change

We often think of climate change as what we can see and feel – in the form of winter storms, blazingly hot days, rising sea levels and parched wheat fields. Catastrophic events like Superstorm Sandy and Hurricane Katrina are examples of what more and more scientists now believe are the end products of global warming.

Figuring out how to measure climate change, therefore, has been on climatologists’ to-do list for some time. And thanks to a research team in Israel, science may be just that much closer to confirming the long-term effects of greenhouse gases.

Investigators at Tel Aviv University have found a way to use Very Low Frequency radio waves (VLF) to measure temperatures at the lower end of the ionosphere (the lower boundary called the mesopause). This discovery is important, because it confirms, among other things, that there is a correlation between the pollution we produce on earth and what happens in the upper atmosphere.

Interestingly, it also confirms that what happens in the upper atmosphere, directly affects technology we depend upon here on earth.

Professor Colin Price and PhD candidate Israel Silber used radio antennae on the ground to measure radio signals around the globe. They discovered that there is a correlation between temperature fluctuations in the upper atmosphere and the varying strength of the radio signals.

The temperature fluctuations in the ionosphere have long been attributed to the proliferation of greenhouse gases on earth. Greenhouse gases act as a shield to escaping infrared radiation from Earth, resulting in warming temps. But in the upper atmosphere, the result is a cooling effect that causes the atmosphere to shrink, moving closer to the planet. It is believed that this process also affects the radio waves passing through the ionosphere.

“We have found a strong anti-correlation between the intensity/amplitude of low-frequency radio waves measured in our 'backyard' and changes in temperature of the upper atmosphere/lower ionosphere,” Price said in an interview with PhysicsWorld.com. According to Price, the warming and cooling of the lower region of the ionosphere affects radio wave amplitude.

Measurements of mesopause fluctuations have been historically difficult to carry out because of its location and its inaccessibility to weather balloons (which are limited to the lower atmosphere) and satellites in space. This discovery offers an inexpensive way to measure climate change from the ground using VLF radio waves. VLF radio waves are those waves that are commonly used for data transmission, such as government time radio signals and military purposes.

Professor Price is also responsible for discovering a link between lightning and climate change, climate change and violent weather,  and the interpretation of lightning during hurricanes.

Image of lightning storm courtesy of NOAA

Image of VLF towers courtesy of Rolf Broberg