Jesus meets Judas

Engineering faces a future with a big carbon problem. Large segments of the engineering community are working toward a future of one day producing energy without, or with greatly reduced levels of carbon dioxide emitting fossil fuels. Our dependency on carbon based fuels will be extremely difficult to break - - but people can generally see a path with reasonable alternatives and solutions. The story of nitrogen is far different - - the story of nitrogen reads as part Jesus and part Judas.

The world’s ability to grow food at the current quantities and range of prices is a function of our ability to produce and distribute synthetic fertilizer - - namely synthetic nitrogen. Civilizations around the globe are generating reactive nitrogen and injecting it into the environment at an accelerating pace. This is driven by fertilizer-intensive endeavors such as biofuel synthesis and meat production. By 2005, humans were creating more than 400 billion pounds of reactive nitrogen each year (about 130 pounds per person), an amount at least double that of all natural processes. If you look at the time scale of synthetic nitrogen application, starting in 1909 with the invention of the Haber-Bosch synthesis process, more than half of the synthetic nitrogen fertilizer ever produced was applied in the past 20-years. When compared to carbon, the production of synthetic nitrogen has skyrocketed 80 percent since 1960, dwarfing the 25 percent increase in atmospheric carbon dioxide over the same period. As we go from a global population of six billion to nine billion (at the current per capita application rates - - this would translate into an annual production rate of 1.2 trillion pounds of reactive nitrogen) - - sustaining this much life starts with food production that needs synthetic nitrogen fertilizer. The miracle of life is the miracle of the Haber-Bosch process - - it is the Jesus part of the story.

We also have a big nitrogen problem - - this is the Judas chapter of the story. Human activities have tripled the amount of reactive nitrogen released into terrestrial environments and coastal oceans every year. As nitrogen-laden river systems enter the ocean, they trigger blooms of microscopic plants that consume oxygen as they decompose, leading later to so-called dead zones. Southern Brazil is a perfect example where population growth and industrialization around Sao Paulo, poor wastewater treatment, and vibrant sugar cane production all contribute to a nitrogen hot pocket off the eastern coast of South America. Nitrogen production is not just limited to water - - mounting evidence also blames reactive nitrogen for an increasingly important role in climate change. One molecule of nitrous oxide has approximately 300 times the greenhouse warming potential of carbon dioxide. Judas might become Jesus if nitrogen causes forests to grow faster or if nitrogen forms aerosols that help to block incoming radiation - - but most experts believe that nitrogen will speed up climate warming.

The paradox of nitrogen - - part Jesus and part Judas, mirrors the paradoxes, trade-offs, economics, and the interconnections of our systems and global communities that engineering is going to have to get more comfortable embracing. Nitrogen clearly gives us life - - it also clearly has the potential to take it away. Both carbon and nitrogen cycle problems illustrate the complexity of sustainability issues and debates. In many areas, sustainability is not about technology and innovation. Sustainability is in some respects about cultural and attitudinal change - - technology and innovation may be a force, but it alone cannot be the complete answer. It’s up to the individual - - making certain personal choices to reduce your carbon and nitrogen footprints. Supporting wind power, hybrid cars, and other policies designed to reduce fossil-fuel consumption are examples on the carbon side. Choosing grass-fed beef and eating less meat, such as a Mediterranean diet, could help to reduce our nitrogen consumption by 50 percent.

None of this is going to be easy or quick or efficient or economical in the context of a historical comparison with the Age of Oil. Problems with both the carbon and nitrogen cycles illustrates the complexity and interconnectiveness of the two systems - - where energy public policy, climate change, food production , and sustainability all come down different paths and meet at the same point. In some cases, as with nitrogen, it is the place where Jesus meets Judas.

Read the February 2010 issue of Scientific American, “Fixing the Global Nitrogen Problem.”