Tech Talk | Shading the Sun

Shading the Sun and other forms of geoengineering are increasingly being mooted to slow the pace of global warming.

As I was thinking about the content of this week’s tech talk, an article appeared in the popular press about a proposed plan to sheath the edge of the Thwaites glacier in Antarctica with a 100km long curtain to protect it from melting and potentially raising sea levels up to a suggested three metres.

The argument is that while a slow melt occurs as the warmer undersea current comes into contact with the edge of the glacier, as the climate warms so the undersea currents get warmer and the melting accelerates.

Moreover with that warming also the winter refreezing results in less ice recovery.

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Such geoengineering, or ‘engineering’ of the climate, is increasingly being talked about as scientists look for ways to slow or halt global warming.

Indeed, it is already being practised in the form of carbon capture from the atmosphere.

John Moore, professor of climate change at the University of Lapland’s Arctic Centre in Finland, is said to be on a mission to save the Thwaites glacier and quoted as expressing confidence the Antarctic Treaty countries will foot the $50 billion bill.

Cool Earth

So too is Yoram Rosen, director of the Asher Space Research Institute at the Technion Israel, who also has been in the news recently with a different type of geoengineering mission – in this case by placing a large shield out in space between the Sun and Earth to reduce the amount of solar radiation reaching the Earth.

The Institute, which claims to be developing a demonstrator in collaboration with the National Centre for Space and Science in the United Arab Emirates and the Israeli geospatial company ImageSat International, believes that a large-scale initiative has the potential to contribute significantly to the reduction of global warming by up to 1.5^oC.

The ‘Cool Earth’ proposal is to place the satellite at the first Lagrange point – a distance of about 1.5 million kilometres from the Earth towards the Sun where the gravitational forces of the two bodies cancel each other allowing a satellite there to remain in essentially a fixed position.

In practice, the satellite would exhibit a slight back-and-forth motion by controlling the shading sail, which also could be used to alter the amount of solar shading according to global climate needs.

“This ground-breaking project offers an original way to cope with the global climate crisis and perhaps even stop its destructive effects,” asserts the Institute’s website.

“Controlling the amount of energy that reaches the earth from the sun may even allow humanity in the future to directly control the desired climate over areas of interest on the earth and possibly prevent droughts and other climate-related natural disasters.”

The Asher researchers have estimated that to achieve the desired temperature reduction, the shade would need to be around 2.5 million km2 in extent – for perspective, in size between the areas of Saudi Arabia and Argentina.

The researchers haven’t stated when they expect the demonstrator to be ready to fly but there are numerous hurdles to be overcome before a large-scale initiative such as this – or any other large-scale geoengineering proposal – could be put into practice, not least the moral with the potential unknown side effect that could occur.

In a recent paper, modelling solar geoengineering – such as the Asher Institute proposal – and carbon dioxide removal, Moore of the Thwaites glacier proposal and the co-authors suggest that combined with the standard mitigation measures they could help to limit global warming.

However, they conclude more cautiously: “Scientific uncertainties surrounding the effectiveness, scalability, and long-term impacts of solar geoengineering and carbon dioxide removal techniques necessitate comprehensive research, rigorous modelling and robust international collaboration to mitigate the risks inherent in unintended consequences and to inform responsible decision-making.”

What are your views on solar geoengineering and should it pursued?

Jonathan Spencer Jones

Specialist writer
Smart Energy International

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