Planetary Intervention (Geoengineering)

Threat of abrupt climate change

Having increased atmospheric greenhouse gases by a third in only a century there is now a risk that the climate might change out of all recognition, in the space of only a few years.  So, now people are debating methods of intervening, including removal of atmospheric greenhouse gases and cooling the planet by increasing its albedo (reflecting more sunshine out to space).

Reducing atmospheric greenhouse gases

Carbon dioxide removal (CDR)

The most easily scalable CDR proposal is very slowly to fertilise barren, sun-drenched areas of the ocean with trace minerals using a method called Buoyant Flake Ocean Fertilisation.  This has been estimated potentially to sequester 22-47Gt CO2/year for an estimated $10 per tonne of CO2. At the same time it would also absorb some undersea methane releases, increase ocean albedo, boost fish stocks and restore ocean health generally. Field trials off the west coast of India are reportedly going well:

Many other interesting methods for removing atmospheric greenhouse gases are described in Drawdown, a book edited by Paul Hawken, the best of which are featured as game changers in Agriculture and Forestry

Atmospheric Methane reduction

Atmospheric methane can be oxidised a thousand times faster than otherwise, by spraying of a mixture of brine and ferric chloride nano-droplets.

Cooling the planet

Even if atmospheric greenhouse gas removal is scaled up quickly it is unlikely to prevent an Arctic tipping point from being reached. Therefore, direct planetary cooling is likely to be needed.

The two safest cooling methods are likely to be Marine Cloud Brightening and Polar Ice Thickening. These proposals are still in their infancy and need further funding for research and development. 

Spraying sulphate aerosols into the upper stratosphere is a much cheaper, quicker cooling method. However it could worsen existing droughts and cause new ones, reduce agricultural yields and suppress forestry growth.  Further massive intervention may then be needed to correct these side effects. In his book The Madhouse Effect, Climate scientist Prof Michael Mann likens stratospheric sulphate spraying to the children’s song There was an old lady who swallowed a fly, which ends “There was an old lady who swallowed a horse. She’s dead of course.”


Some people worry that if geoengineering successfully compensates for carbon intensive economic activity, there will be reduced motivation to rein in greenhouse gas emissions, a condition they describe as ‘moral hazard’. In addition they say it is morally wrong to carry out large-scale experiments on planet Earth.

Need for research

However, having already inadvertently carried out a very dangerous experiment on Earth’s atmosphere, experts are now saying it is time to begin seriously researching the safest methods, to avoid total catastrophe.

Who will pay?

This is a thorny question especially for planetary cooling, because there is no profit to be made, only prevention of bad things happening at indeterminate times in the future. Nation states have evolved mechanisms to fund prevention of future ‘bads’, such as defence budgets. However, the global community has only weak funding mechanisms, such as voluntary pledges. All too often pledges are not honoured.

recently proposed funding source is the reinsurance industry. It is a globalised industry and will suffer directly as climate impacts become increasingly disastrous. It therefore has has the most direct interest in seeing geoengineering programs succeed. Funds would be obtained by placing a premium on fossil fuel extraction. Fossil fuel companies would have to pay this premium or be uninsured, and therefore unable to operate.

Of course, this would place a cost on energy which we would all end up paying, and economies would suffer as a result, at least a little. It’s a hard choice. No doubt there would be push-back from the fossil fuel companies and their shareholders. In a way, it’s the same old problem – that mankind has become overly reliant on ‘borrowing from the future’. This proposal will only be successful if it receives sufficient government support. And governments cannot enact policies without sufficient public support.


Geoengineering governance will be needed to ensure that experimentation and any deployment of geoengineering techniques are safe, fair, effective and economic. The Oxford Principles are an example of a proposed geoengineering governance framework.

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