George Burba

A research station in the Arctic sends data via radio links

Radiocommunications and climate change

Timely warning of impending natural disasters, accurate climate prediction and detailed understanding of the status of global water resources — these are just some of the critically important challenges for the global community. Radiocommunications are essential in answering them all as we tackle the consequences of climate change.

The science of climate change has benefited greatly from the parallel development of information and communication technologies (ICT) in general, and radio technologies in particular. The role of radiocommunications in weather and climate monitoring is clearly shown, for example, in the structure of the World Meteorological Organization’s Global Observing System (GOS), which provides observations of the atmosphere and the Earth’s surface, including oceans. It uses remote sensing equipment placed on satellites, aircraft, and radiosondes in weather balloons, the data from which are relayed via radio links to environmental control centres.

Radio-based environmental monitoring devices track the progress of hurricanes, typhoons, tornadoes, thunderstorms, and the fumes from volcanoes and major forest fires. Weather forecasts would be much less accurate without radio systems collecting and processing meteorological data. Satellite communications disseminate information to remote areas and, of course, radio and television broadcasts are central in warning the public about dangerous weather or environmental events. Increasingly too, such information is being sent to mobile phones and other wireless devices.

Measuring global warming

Remote sensors come in two types: “passive” sensors record radiation being reflected by the object under study. “Active” sensors transmit radio waves and measure the reflected signal, as for example the radar altimeter illustrated in Figure 1. Gathered data are processed and analysed by computer. A practical and very important example of remote sensing is in the monitoring of global warming.

In order to promote countermeasures, it is essential to monitor the state of global warming precisely, and for this purpose it is necessary to observe the concentration and increase or decrease in greenhouse gases (GHG) throughout the world. Global monitoring of GHG is performed by remote sensors on board satellites. These sensors can observe the concentration and distribution of greenhouse gases, as well as monitor their absorption and emission. A global satellite map of carbon dioxide distribution, based on remote sensing data, is shown in Figure 2. The launch of a Japanese satellite dedicated to monitoring greenhouse gases in Earth’s atmosphere was described in ITU News of January–February 2009.

Increasing temperatures at the ocean surface are among the factors governing violent storms, hurricanes and rising sea levels. This is another area that is being monitored by remote sensing from satellites. The surface temperature of the sea can be measured to within an accuracy of 0.2°C (see Figure 3).

It is important to remember that the radio-frequency bands used for remote sensing need to incorporate the frequencies that are needed in monitoring particular substances, such as water vapour or carbon dioxide gas. The unalterable physical properties of each substance mean that only specific frequencies can be used to detect them and extract environmental information. This determines the choice of spectrum that can be allocated for this purpose.

Adaptation and mitigation

Adaptation to the adverse effects of climate change is a key issue everywhere, but especially for developing countries, which are often the most vulnerable and the least equipped to protect their populations. Radiocommunications themselves are contributing to the problem of climate change because of the proliferation of wireless devices (such as televisions, transmitters and mobile phones), all of which need power and radiate heat. However, radiocommunications, like other forms of ICT, can also do a great deal to help. The main ways in which they do so are by:

• Mitigating greenhouse-gas emissions from radio equipment, and helping other sectors to reduce emissions through using, for instance, videoconferencing
• Providing environmental information for building effective national and international mitigation and adaptation strategies
• Developing systems for climate monitoring, disaster prediction and detection, early warning and disaster relief.

A good example of the mitigation of greenhouse-gas emissions from radio systems can be seen in the switchover from analogue to digital broadcasting. The use of digital modulation means that transmitters need almost ten times less power. Taking into account that there are hundreds of thousands of transmitters around the world, some using up to 100–150 kW of electricity, the results can be very significant. Moreover, the number of transmitters may be reduced due to the possibility of transmitting up to ten television programmes over a single 8 MHz channel, instead of one programme per channel.

Dealing with natural disasters

Disaster prediction and detection is an important function of Earth exploration satellites, which also provide the relevant data to emergency telecommunication systems for distribution of early warnings. In addition, remote sensing by satellite is used to monitor one of the most dangerous consequences of climate change — rising sea levels that may flood coasts worldwide, with some small island States facing complete inundation. Figure 1 shows an example of a satellite equipped with an altimeter for measuring sea levels. Modern altimeters can identify a change in level with a precision of two-to-three centimetres.

Radiocommunication systems are especially important in disaster relief operations because, in many cases, the wired telecommunication infrastructure is damaged or destroyed by a disaster and only wireless systems can be used (especially satellite and high-frequency terrestrial systems). That is why deploying wireless communications is typically among the first priorities in any emergency response, rescue, and relief operation.

Satellite communications (see Figure 4) can make a real difference during the first crucial hours and days after a disaster. They are employed to assess the extent of damage, help locate survivors, measure the potential danger for rescue teams and ensure that humanitarian response crews can communicate effectively with their team members, other agencies, local hospitals and paramedics. And the victims of a disaster, too, can contact rescuers and speak to loved ones — all through the power of radiocommunications.