Climate change: Cooling the planet with concrete, seaweed and rocks

[Global] When he’s not discovering new mammal species in Pacific islands and dinosaur fossils in Australia, scientist Tim Flannery of Melbourne University is a prominent environmental activist and bestselling author. Flannery’s latest book Atmosphere of Hope takes a bold optimistic step to suggest new ways of fighting global warming.

Excerpts from an interview with Subodh Varma…

You have proposed new ways of fighting climate change, calling them ‘third way’ technologies. Why that name? Currently, there are three ways of combating climate change. The first way, which is the focus of traditional climate talks, involves reducing emissions of greenhouse gases. It is vital that we reduce emissions as hard and fast as humanly possible. But because we have let emissions grow for decades, it will be all but impossible, using this approach alone, to avoid breaching the 2°C ‘safety rail’ beyond which we face increasing risk of seriously destabilising Earth’s climate system.

A second way involves planetary geoengineering, for example, by injecting sulphur into the stratosphere to cool earth’s surface. A fundamental objection to geoengineering is that it is a ‘band-aid solution’ which does nothing to address the root cause of the problem. Because of the high probability of unintended consequences, most scientists consider geoengineering extremely high risk – for example it may destabilise the south Asian monsoon.

Despite the risks, some countries which face serious consequences from climate change are investigating it. China, for example, currently has four research teams looking into geoengineering.

A third way of combating climate change is to draw enough CO2 out of the atmosphere to make a difference to our climate future. This is a huge task, a drawdown of 18 gigatonnes of CO2 being required to decrease atmospheric concentrations of CO2 by 1 part per million. Until recently it has been unclear whether this is even possible, but I argue in my book Atmosphere of Hope that by 2050, third way technologies might be drawing 40 per cent of current emissions (around 16 gigatonnes) from the atmosphere annually .

What are these third way technologies? Third way technologies are incredibly varied, but these can be classified into two fundamental approaches; biological and chemical.

Biological approaches include initiatives such as reafforestation, the production of biochar, and wood chemistry technologies but because of constraints, these land-based solutions can only provide a part, most probably a small part – of the solution. Seaweed farming with sequestration of CO2 in offshore sediments offers greater potential, but is at a very early stage of development.

Chemical pathways include the manufacture of carbon negative cements. These can be used to make concrete that draws CO2 into its structure as it matures. They already exist, but make up just a tiny fraction of the current cement industry . An other approach is the use of serpentinite rocks, which sequester CO2 from the atmosphere as they weather.

Five to six gigatonnes of ground up serpentinite rock could capture 3-4 gigatonnes of atmospheric CO2. But of course we use fossil fuels to quarry and grind up rock, and only when we can green this process will it be worthwhile. The manufacture of plastics and carbon fibres from CO2 has been demonstrated, but even if all plastics and carbon fibres currently used were made from atmospheric CO2, less than 3 gigatonnes of CO2 would be captured. There is also the possibility of chilling the air over the Antarctic ice cap to cause CO2 to drop out of the air as ‘snow’ and burying in in the ice cap. All of these approaches are either in a very early stage of development, or are at best nascent industries.

These technologies will need more research, more money. Who will pay? Development pathways for third way technologies are likely to be decades long. If we hope to be using them at the gigatonne scale by 2050, we need to begin investing now. Some third way technologies, such as seaweed farming, and CO2 to plastics or carbon fibres, require more research dollars. Other approaches such as the use of serpentinite rocks will need to be funded via a global carbon price or some other source.

Do you think the Paris climate change talks will deliver? The Paris climate process is already a success in that most nations have pledged actions to reduce their greenhouse gas emissions. Their actions will not be enough to avoid dangerous climate change, but are a good start. Combined with a shorter review period for pledges, and serious funding for the least developed countries, Paris could re-set the world’s climate trajectory .

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