Changing the way farmers plough their lands could have a big impact on global emissions of greenhouse gases.

Changing farming practices could play an important role in averting dangerous climate change says the UN. In their annual emissions report, they measure the difference between the pledges that countries have made to cut warming gases and the targets required to keep temperatures below 2C. On present trends there is likely to be an annual excess of 8 to 12 gigatonnes of these gases by 2020.

Agriculture, they say, could make a significant difference to the gap. This is the fourth such report, compiled by the United Nations Environment Programme (Unep) in conjunction with 44 scientific groups in 17 countries. It says the world needs to reduce total emissions to 44 gigatonnes of carbon dioxide equivalent by 2020 to keep the planet from going above the 2C target, agreed at a UN meeting in Cancun in 2010. But when all the pledges and plans made by countries are added together, they show an excess of between 8 and 12 gigatonnes per annum in seven years time, very similar to last year's report. To put it in context, 12 gigatonnes is about 80% of all the emissions coming from all the power plants in the world right now.