The pie chart shows that there are four main causes of farmland becoming degraded in the world today. Globally, 65% of degradation in caused by too much animal grazing and tree clearance, constituting 35% and 30% respectively. A further 28% of global degradation is due to over-cultivation of crops. Other causes account for only 7% collectively.
These causes affected different regions differently in the 1990s, with Europe having as much as 9.8% of degradation due to deforestation, while the impact of this on Oceania and North America was minimal, with only 1.7% and 0.2% of land affected respectively. Europe, with the highest overall percentage of land degraded (23%), also suffered from over-cultivation (7.7%) and over-grazing (5.5%). In contrast, Oceania had 13% of degraded farmland and this was mainly due to over-grazing (11.3%). North America had a lower proportion of degraded land at only 5%, and the main causes of this were over-cultivation (3.3%) and, to a lesser extent, over-grazing (1 .5%).