The debate over whether people should start geoengineering the atmosphere in order to prevent the worst effects of global warming ignores one essential fact – we already are geoengineering the atmosphere. Geoengineering is the deliberate effort to manipulate processes that control conditions in the atmosphere on a global scale. Last month, March 2013, marked the centennial anniversary of the invention of the Haber-Bosch process, an industrial process for “fixing” nitrogen by producing ammonia from nitrogen in the atmosphere. Using the Haber-Bosch process, people now have a large influence over the global nitrogen cycle. Earth is a planet that is mostly covered by water and surrounded by an atmosphere that is mostly composed of nitrogen. Yet, it is one of the ironies of nature that so much of the life here is organized around a constant struggle to secure sufficient water and nitrogen. Nitrogen is, of course, an essential plant nutrient and a key element in the protein molecules that make up our bodies. Just as the water of the oceans is unfit for us to drink, most plants cannot use the dinitrogen gas, N2, that makes up 78% of the atmosphere. Until the 20th century, plants and animals had to depend almost entirely on microbes to scavenge nitrogen from the atmosphere. A few microorganisms have the ability to “fix” dinitrogen gas, converting nitrogen from the atmosphere into a form that plants can use; lightning is also responsible for a small amount of nitrogen fixation. - See more at: http://ian.umces.edu/blog/2013/04/26/celebrating-100-years-of-industrial-nitrogen-fixation/#sthash.HYwzFuF5.dpuf