What is climate engineering?

The Forum for Climate Engineering Assessment is defining climate engineering as ‘technological interventions that are being imagined or developed to mitigate climate change or to blunt its impacts.’

The definition and use of the term ‘climate engineering’ or ‘geoengineering’ is not fully agreed upon, and given what is at stake, can be contentious.  Each definition is politically loaded, represents perspectives, and involves choices to include or exclude certain kind or types of actions, impacting arguments surrounding its potential benefits and risks.

The U.N. I.P.C.C.’s A.R.5 Working Group 1 report defines climate engineering as ‘methods that aim to deliberately alter the climate system to counter climate change.’1

A U.N. Convention on Biological Diversity document on the definition of climate engineering released in a 2012 peer-reviewed report “Impacts of Climate-related Geoengineering on Biological Diversity,” defined geoengineering as “a deliberate intervention in the planetary environment of a nature and scale intended to counteract anthropogenic climate change and its impacts.”2

The Oxford Geoengineering Programme defines geoengineering as ‘the deliberate large-scale intervention in the Earth’s natural systems to counteract climate change.’3

Members of a public Google discussion group on geoengineering, which features conversation among some of the leading voices in the global geoengineering ‘conversation,’ discussed the merits of defining geoengineering as ‘activities intended to modify climate which have a greater than de minimis effect on an international commons or across international borders and where that greater than de minimis effect occurs through environmental mechanisms that are not a direct consequence of any resulting reduction in anthropogenic aerosol and/or greenhouse gas concentrations.’4

Those who think and write about geoengineering most often divide proposed schemes into two categories. Carbon Dioxide Removal (CDR) schemes are being designed or imagined to draw carbon dioxide out of the atmosphere, to render it inert and store it in some kind of safe, long-term fashion, or to use it for fuel. At large enough a scale, planting trees, or remediating soil through the integration of a substance like biochar, would qualify.  Often discussed CDR schemes include iron ocean seeding—dropping iron into the oceans to encourage carbon-inhaling blooms of plankton, artificial trees—a theoretical system that could draw carbon dioxide directly from the open air, enhanced weathering and ambient air capture.

Solar Radiation Management (SRM)5 technologies are those that would reflect some amount of incoming solar radiation back into space, or that would more readily enable heat radiated from the earth’s surface to escape, reducing regional or planetary warming. It has been estimated that reflecting around 2% of incoming solar radiation would offset the global temperature increase associated with a doubling of pre-industrial levels of carbon dioxide.

SRM would basically involve making some part of the planet’s surface or atmosphere more reflective. Genetically engineered crops with shinier leaves, or massive white plastic sheets deployed over melting glaciers, or micro-bubbles in the earth’s oceans have been posited as ground-level options. Moving up, some have envisaged ways to brighten cloud layers in the lower atmosphere. The most often discussed potential SRM intervention would be the introduction of sulphate particles or a similar substance into the stratosphere or troposphere, to mimic the cooling effect of volcanic eruptions.

Here is the Wikipedia entry for ‘climate engineering,’ termed an ‘application of geoengineering.’


  1. IPCC Climate Change 2013, The Physical Science Basis (Working Group 1) http://www.ipcc.ch/report/ar5/wg1/
  2. ADDITIONAL INFORMATION ON OPTIONS FOR DEFINITIONS OF CLIMATE-RELATED GEOENGINEERING http://www.cbd.int/doc/meetings/cop/cop-11/information/cop-11-inf-26-en.pdf
  3. http://www.geoengineering.ox.ac.uk/what-is-geoengineering/what-is-geoengineering/?
  4. Geoengineering Google group: https://groups.google.com/forum/#!forum/geoengineering
  5. The term “solar radiation management” itself is contentious, with some arguing that a more proper wording would be “solar radiation interference.”