Six radical ways to tackle global warming

Reflecting the sun's rays could stop climate change - but with 'terrifying' consequences

Radical, untested techniques to tackle global warming by reflecting the sun's rays could have "terrifying" consequences, yet may ultimately be needed to prevent catastrophic climate change, scientists have said.

Three Government-funded research projects released on Wednesday assessed the potential of controversial processes known as “geoengineering” – deliberately interfering with the earth’s climate to reverse global warming.

The two main types involve limiting solar radiation to cool the planet, or sucking carbon dioxide – one of the biggest causes of global warming - back out of the atmosphere.

Dr Matthew Watson of the University of Bristol, one of the scientists behind the research, said that techniques that reflect solar radiation to cool the earth could have “profoundly terrifying” negative consequences by shifting extreme drought and rainfall weather patterns to different regions – for example shifting the arid Saharan desert conditions south over populated areas of Africa.

Some of the techniques could also damage the ozone layer, leaving people at risk of skin cancer, or potentially trigger conflicts amid tensions between those affected by their deployment, the scientists said.

Research by Professor Piers Forster of the University of Leeds found that six mooted techniques for managing solar radiation could all leave billions of people with worse rainfall patterns – whether rainfall or drought – than before.

Yet Dr Watson argued that if the world keeps on its current trajectory toward “catastrophic” global warming by burning fossil fuels, then the techniques may nevertheless need to be used within decades to avert even greater disaster. “There is a point at which not deploying some technologies would be unethical,” he said.

While untested, the techniques to reflect solar rays could nevertheless be relatively easy to implement, the scientists said.


Different types of geoengineering to suck carbon dioxide out of the atmosphere were based on existing technologies but would take decades to deploy on the vast scale needed, the scientists said.

They could also have drawbacks. For example, growing vast new forests to absorb carbon dioxide, or to burn as biomass energy, could use up land needed for crops, threatening food supplies.

Other carbon dioxide-removal techniques involve dumping iron filings in the seas in order to encourage the growth of plankton, which absorb carbon. But this is also highly controversial and could potentially damage marine life, the scientists said.

Six ways of limiting solar radiation:‘Fake volcanoes’

Pumping sulphate aerosol particles into the atmosphere, mimicking the effects of a volcano – reflecting more sunlight back into space.

2.8 billion people could be left with damaging rainfall effects, leaving them worse off than before.

Cirrus cloud thinning

Thinning the highest layer of clouds, which otherwise act as a blanket, retaining heat.

2.4 billion people could be left with damaging rainfall effects.

Reflective ocean clouds

Spraying sea salt particles into clouds over the oceans so that they reflect more of the sun’s rays.

3 billion people could be left with damaging rainfall effects.

Reflective oceans

Producing “microbubbles” by the surface of the ocean to make it more reflective. Ships could be fitted with technology to make their wakes more “frothy”.

2 billion people could be left with damaging rainfall effects.

Reflective deserts

Installing shiny surfaces over the desert area.

4.1 billion people could be left with damaging rainfall effects.

Reflective crops

Growing different kind of crops that are more reflective.


1.4 billion people could be left with damaging rainfall effects.