New Method to Measure Climate Change: Radio Waves

Climate change is happening around the world and scientists are continually updating the ways they measure its influence. Now, researchers have discovered another way to measure climate change. They've found that radio waves reflected back to Earth from the ionosphere offer valuable news on our shifting environment.

The ionosphere is one of the regions of the upper atmosphere. It plays a crucial role in global communications. Because it's ionized by solar radiation, the electricity-rich region can transmit long wave communications, such as radio waves. The strength of these radio signals on the ground, though, seems to be able to indicate exactly what temperatures are like above in the atmosphere. This, in turn, could allow researchers to predict climate change.

In this latest study, the scientists used simple radio antennae on the ground to measure radio waves broadcast by navigational transmitters around the globe. They then compared this information on the strength of these radio signals with data on temperature fluctuations in the upper atmosphere. They found that climate change in the upper atmosphere, caused by an abundance of greenhouse gases, could lead to a greater absorption of radio waves. In fact, weaker radio signals could be an indicator of greater climate change.

On Earth's surface and in the lower atmosphere, an increase of greenhouse gases has a warming effect. The gases, which include carbon dioxide, are increasing in the upper atmosphere as well. There, surprisingly, they have a cooling effect.

When the ionosphere cools, it contracts and descends into the atmosphere to where air is denser. That causes a higher absorption of radio waves. By examining satellite-gathered data on the temperature in the upper atmosphere and comparing results to measurements of radio wave amplitudes collected on the ground, the researchers uncovered a clear correlation between the two.

This new technique could be a valuable addition to the current methods of monitoring climate change, such as the measurement of ground temperatures. In addition, it doesn't require expensive equipment like satellites to monitor the upper atmosphere. Instead, it can be done inexpensively and continuously.

The findings are published in the Journal of Geophysical Research.