The intensification of agriculture, including the application of pesticides, artificial fertilisers and irrigation, has just as great an effect on global warming as changes to use, such as turning forest into agricultural or urban areas. This is demonstrated by research from Alterra, VU University Amsterdam and other authors which was published yesterday in the journal Nature Climate Change. The research shows that increasing demand for food can contribute to the severity of climate change.
Photo: in order to properly evaluate the influence of human activity on climate, the effects of land management also have to be taken into account.
Changing land cover affects climate
A team led by Sebastiaan Luyssaert (LSCE) and consisting of Eddy Moors (Alterra Wageningen UR), Han Dolman (VU University Amsterdam) and others has used field measurements (including from the Loobos site on the Veluwe hills) combined with satellite measurements to study the direct climatological effects of changes to land cover and land management. If all cooling and warming aspects are taken into account, the net effect in both cases is local warming of approximately 1.7 °C in the lowest level of the atmosphere.
This study demonstrates a similarity between the effects of changes to land cover and changes to land management which casts new light on the causes of climate change. Historic changes to land cover, such as in Europe and the United States, have been accorded less weight in political negotiations than more recent changes to land cover in Latin America and South-east Asia.
Major biophysical effects
'The results of our study imply that in order to properly evaluate the influence of human activity on climate, the effects of land management also have to be taken into account,' says Alterra researcher Eddy Moors. 'This is true, for instance, for the climatological consequences of the recent intensification of land management without changes to land cover, such as the Green Revolution in Europe, the United States, China and India. The major biophysical effects of changes to both land cover and land management which we discussed in our study demonstrate that the current awareness of the relation of these changes to greenhouse gas emissions must be expanded to include warming as a result of direct biophysical effects.
Taking climate into account when intensifying agricultureAccording to the researchers, this means that when considering various policy options for intensifying agriculture in order to meet the increasing demand for food, it is important to take into account both greenhouse gas emissions and the direct climatological consequences of those emissions.