Researchers at the University of Cambridge have measured how much carbon is produced by fertilizers from the beginning to the end of their life cycle. This is important, as fertilizers are responsible for around five percent of all greenhouse gas emissions. This is the first time anyone has accurately measured this. They discovered that by the year 2050, it could be possible to reduce carbon emissions from fertilizers to only one-fifth of what they are now. Researchers have calculated the carbon footprint for the full life cycle of fertilizers, which are responsible for approximately five percent of total greenhouse gas emissions – the first time this has been accurately quantified – and found that carbon emissions could be reduced to one-fifth of current levels by 2050. The researchers, from the University of Cambridge, found that two-thirds of emissions from fertilizers take place after they are spread on fields, with one-third of emissions coming from production processes. Although nitrogen-based fertilizers are already known to be a major source of greenhouse gas emissions, this is the first time that their overall contribution, from production to deployment, has been fully quantified. Their analysis found that manure and synthetic fertilizers emit the equivalent of 2.6 gigatonnes of carbon per year –more than global aviation and shipping combined. Carbon emissions from fertilizers urgently need to be reduced; however, this must be balanced against the need for global food security. Earlier research has estimated that 48% of the global population is fed with crops grown with synthetic fertilizers, and the world’s population is expected to grow by 20% by 2050.