The pie chart below shows the main reasons why agricultural land becomes less productive. The table shows how these causes affected three regions of the world during the 1990s.
Causes of worldwide land degradation
Causes of land degradation by region
The pie chart displays the major causes of global land degradation, while the table illustrates how three regions of the world were affected by these causes during the 1990s.
Overall, over-grazing, deforestation, and over-cultivation are the main reasons why agricultural land worldwide is degraded. In addition, Europe had a much higher percentage of degraded land than Oceania and North America.
Over-grazing, which accounts for 35% of the world’s degraded land, is the single biggest reason for global land degradation. Deforestation and over-cultivation constitute another 30% and 28% respectively.
Of the three regions, Europe had the greatest proportion of degraded land during the 1990s, at 23%. However, there, the biggest factor was not over-grazing but deforestation, which caused 9.8% of the land to become less productive. Oceania was the second most affected region, with a total of 13% of its land degraded, and this was mostly caused by over-grazing, at 11.3%. It is also noteworthy that Oceania didn’t over-cultivate its land. In comparison, only a total of 5% of the land in North America was degraded. Over-cultivation, responsible for 3.3%, was again the biggest cause.
How to Understand the Pie Chart
A certain percentage of the world’s land is degraded, but we are not told what this percentage is. As you can see, the percentages in the pie add up to 100 (35+30+28+7). This doesn’t mean that 100% of the world’s land is degraded. The pie chart only tells us that over-grazing, for example, accounts for 35% of the world’s degraded land, not 35% of all the world’s land. So don’t say something like “35% of land worldwide is degraded by over-grazing”.