Farming is the chief cause of deforestation in the world, but its driving forces are international trade, a growing economy and the increase in meat consumption.
Of indirect influence, too, are the drivers of deforestation, the report stresses, of which the major ones are global economic growth and population increase. These lead to increased meat consumption and thus, more international trade in farming and wood products. 'These indirect causes are more difficult to measure, unfortunately,' says Herold. 'Remote sensing can ascertain that a forest has been converted into farmland but it cannot easily quantify what makes this happen.' However, it remains important, says Herold. If deforestation is the result of international causes, national policies alone would have no effect; international policies would be required too.
A new form of international policy to combat deforestation is REDD: reducing emissions from deforestation and forest degradation. The idea behind this is to reduce the emission of greenhouse gases due to deforestation by getting industrial countries to help pay for the conservation of forests in developing countries. Herold: 'Good REDD policy is targeted at the cause of deforestation.' How deforestation is measured - which is essential to REDD - depends on its cause, explains Herold. If this lies in the increase in commercial farming, remote sensing can be used to measure it. But if the cause is, for example, firewood collection by the local population, measurements have to be done at ground level.