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Insights into Editorial: Cooling the earth down

Insights into Editorial: Cooling the earth down

09 March 2016

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“Climate engineering” has been a buzzword in recent years. Environmentalists believe that climate engineering, along with reduction in carbon emissions, can greatly reduce global warming. 

What is climate engineering?

Climate engineering, also known as geoengineering, describes a diverse and largely hypothetical array of technologies and techniques for intentionally manipulating the global climate, in order to moderate or forestall the (most severe) effects of climate change.

How is it being viewed currently?

Today, climate engineering efforts are viewed either as secondary measures to be undertaken alongside reducing emissions or as technologies which have not matured enough to warrant discussion by world leaders.

Climate engineering efforts can be divided into two categories:

  1. First, removal of Greenhouse gases from the atmosphere:

This basically involves management of carbon. A prominent example is carbon capture and storage (CCS), where some of the carbon dioxide (CO) being emitted by coal-fired power stations is recaptured by physically sucking it in and transporting it elsewhere to be sequestered underground.

Another method for removing CO from the atmosphere is to increase forest cover as plants will absorb some of the unwanted CO. Increased forestation is part of India’s strategy for reducing CO.

However, it is not clear whether CCS, reforestation and other carbon removal methods can make sufficient impact at the global level to significantly slow down global warming. But they seem relatively benign at the scale at which they are being considered now and will at least lower CO pollution locally.

  1. Second category involves Solar Radiation Management or Sunlight Reflection Methods (SRM):

This method aims to reduce the amount of heat trapped by greenhouse gases by reflecting sunlight back into space, either by increasing the reflectivity of the earth’s surfaces, or by deploying a layer of reflective particles in the atmosphere.

  • Among the techniques being considered under SRM are marine cloud brightening, cirrus cloud manipulation and stratospheric aerosol injection (SAI).

Stratospheric aerosol injection (SAI):

SAI, the boldest and also the most risky of climate engineering interventions, involves spraying into the stratosphere fine, light-coloured particles designed to reflect back part of the solar radiation before it reaches and warms the earth. SAI proponents claim that this could bring down the global temperature by as much as 1°C — a substantial amount in the climate change context. Many researchers have already verified this claim.

  • The optimal gases for injection, such as sulphur dioxide (SO), can be produced in abundance. Furthermore, just a few airplanes specially redesigned for the purpose may suffice for injecting the required aerosol into the stratosphere.
  • There are also precedents from nature. The 1991 volcanic eruption of Mount Pinatubo in the Philippines injected 20 megatonnes of SO into the stratosphere, cooling the globe significantly for a couple of years.

climate engineering


  • However, SAI also has the potential for disastrous side effects, crossing national boundaries. The Pinatubo volcanic eruption is also said to have reduced precipitation, soil moisture, and river flow in many regions.
  • Also, injection of sulphur compounds into the stratosphere is likely to increase acid deposition on the ground and also contribute to ozone layer depletion. Apart from such “known unknowns”, there could also be, to use the catchphrase, the “unknown unknowns”.
  • Besides, once the aerosol has been injected into the atmosphere, it cannot be removed. Yet, if for any reason the injection, once begun, is discontinued prematurely, there can be rapid re-warming. That, ironically, could do more damage than the gradual global warming that we are seeking to combat.

Potential threats from SRM:

Worsening climate change may pressurize small nations to resort to using whatever SAI technology is available in the international market. In their desperation, possible harmful effects on other countries may not weigh heavily on their decision-making. Besides, just the fear of possible adverse side effects could lead to war between the nations.

How to deal with this problem?

One simple way to deal with this problem is to just ban further research in these fields. In fact, some climate scientists have already suggested this. They also fear that even the possibility of SRM interventions may undermine efforts to reduce carbon emissions.

Way ahead:

There are also few individuals who think that a blanket ban on SRM would be unwise and difficult to implement. Technology, benign or malevolent, has a way of continuing to advance.

  • The goal of SRM is to mitigate damage done by carbon emissions. If there is some chance of it succeeding safely, it would be unwise to abandon it at this stage.
  • Abandonment would also leave SRM technologies dangling midway, insufficiently tested or refined. That may nevertheless not deter some desperate climate change-afflicted nation from deploying it, leading to disaster.
  • It is only through continuation of responsible research in climate engineering, done under proper regulatory oversight, that the limitations and risks of such interventions can be fully understood and provide the basis for informed decision-making.
  • That will call for international governance mechanisms for overseeing the research and development and possible deployment of climate engineering techniques.


The complexity of the issues associated with engineering the climate presents a challenge for shaping even the most basic research and engagements with the public and policy-makers today. It is difficult to predict how the debate on climate engineering will influence – or be influenced by – future developments in technology, the climate system, or the international order. While active climate engineering researchers have already been conscientiously worrying about these issues, it is not too early for the rest of us to start thinking about it.