Manipulating the climate to cool the planet

When we burn fossil fuels we raise the concentrations of greenhouse gases in our atmosphere. That is changing the Earth's climate. Engineers are now able to manipulate the environment, but most test communities have said they don't trust the technology.

Climate engineers say they can launch mirrors into space, angle them towards the sun and stop the sun's rays from penetrating the atmosphere. Less sunlight means less heat being trapped by greenhouse gas - and that means cooler temperatures. But in a recent study, communties in Australia and New Zealand said solar mirrors were too dangerous, expensive and unpredictable.

Geoengineers have also tested chemical climate control. By launching a tethered balloon into the air and releasing particles into the stratosphere, they say they can turn down the heat. The particles create a global dimming effect and gradually reduce the amount of direct irradiance at the Earth's surface. But test survey participants preferred techniques that make more use of natural processes.

People have shown less reluctance about cloud brightening. This technique entails spraying seawater into the atmosphere, which changes the size distribution of water drops in existing clouds, making them whiter and thicker. This in turn reflects the sun's rays. But the impact of this on the environment is not well understood.

Survey participants also showed less concern about a technique called enhanced weathering. This involves grinding or heating minerals to increase the rate at which they are dissolved by the carbon dioxide in the atmosphere. The limestone which is created traps carbon dioxide for thousands of years. The downside? The process may require a lot of water.

Biochar is charcoal made from vegetation. It locks in carbon dioxide, effectively storing this greenhouse gas for centuries. The problem scientists see is this needs quite a lot of land and right now we need that space for crops. But the public were only moderately opposed to this technique.

The survey was carried out by researchers from Massey University in New Zealand and the University of Southampton the United Kingdom. Co-author Damon Teagle told DW that geoengineering is an option, but called for continued action to reduce emissions and improve energy efficiency in order to protect the climate.