Geo-engineering the Climate

  • Carbon dioxide emissions add to the "greenhouse" effect in the atmosphere, causing a warming effect. Photo: John Giles/PA Wire

    Solar Radiation Management (SRM) methods may directly cool the atmosphere by blocking, or diverting, incoming solar radiation. Photo: Yui Mok/PA Wire

    Carbon Dioxide Removal (CDR) methods may directly combat climate change by removing carbon dioxide from the atmosphere. One such way is to replant vegetation. Photo: Martin Keene / PA

  • Geo-engineering the Climate
    03.12.2011 16:38


    On the back of news that revealed November 2011 was the second warmest November since records began, questions are being thrown up again about global warming; its impacts and what, if anything, can be done to mitigate its effects. An obvious answer is to cut emissions of greenhouse gases around the world, but this is easier said than done in today’s highly developed and industrial planet. As a result, there has been significant research into “Geo-engineering” to reduce, mitigate and adapt to climate change.

    The two methods of this “Geo-engineering” are Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM). Whilst both methods have considerable strengths; their effectiveness, timescale of use, ease of implementation and level of control must be called into question before large sums of money are spent developing them. 

    CDR methods involve the removal of carbon dioxide from the atmosphere and directly combat the problem of global warming by reducing the “greenhouse” effect. Land-based methods include the use of artificial trees that remove more carbon dioxide than natural trees, the replanting of crops and vegetation and using a special “biochar” that creates a carbon sink on land. There are also ocean-based methods, such as fertilizing surface waters with chemicals to increase their intake of carbon dioxide.

    SRM methods on the other hand involve directly reducing the incoming solar radiation from the sun. One such way is to make the earth more reflective (increasing the albedo) by painting roofs white, growing highly reflective crops and placing giant mirrors on the earth’s surface. Since more radiation is reflected back into space, less is trapped in the atmosphere thus reducing the warming effect. Another method is to divert incoming solar radiation by placing sunshades in space – directly cooling the planet.

    From a general perspective, CDR methods of geo-engineering have the advantage over SRM methods in directly addressing the root cause of global warming:  by removing carbon dioxide from the atmosphere. Therefore since SRM methods still allow the build-up of carbon in the atmosphere, there will be a real problem if they suddenly cease to work. On the other hand, SRM methods are far more effective due to being able to cool the atmosphere much more quickly after deployment, which is a major advantage when faced with an ever-warming planet. 

    Both SRM and CDR methods therefore could be undertaken adjacently to maximise the effectiveness of reducing the effects of global warming. Current research into geo-engineering is continually suggesting new and innovative ways to tackle the problem of climate change and in the near future we could see many of the methods being implemented.


    By: Nick Prebble