Arable Land Loss

Soil degradation is a serious problem. I care very much about environmental protection and the long-term sustainability of agriculture around the world.

This is why it upsets me that a demonstrably false claim is currently circulating in the news media.

"...nearly 33 per cent of the world's arable land has been lost to erosion or pollution in the last 40 years ..." (phys.org, sciencealert.com)

"... nearly 33% of the world’s adequate or high-quality food-producing land has been lost ..." (theguardian.come, rt.com)

experts from the University of Sheffield's Grantham Centre for Sustainable Futures revealed that nearly 33 per cent of the world's arable land has been lost to erosion or pollution in the last 40 years

Read more at: http://phys.org/news/2015-12-soil-lossan-unfolding-global-disaster.html#jCp

This claim was delivered to the news media by the The University of Sheffield's Grantham Centre for Sustainable Futures which is a political research and advocacy organization. They've circulated a pamphlet and press release which both repeat the "33%" statistic without any indication how the number was calculated.

I suspect they got the number from the FAO website which says:

"... 33 percent of the global arable land used to producing feed for livestock ..."

Or perhaps they misunderstood this description of FAO data:

"Agricultural land covers 33% of the world's land area, with arable land representing less than one-third of agricultural land (9.3% of the world's land area)."

Whatever their mistake, we can use the FAO data to find out for ourselves how world-wide arable land area has changed over time. By multiplying the fraction of arable land by the total land area of each country we get the graph below.

Arable land is not being lost. Click here for the raw data.

But changes in "arable land" over time isn't even useful for measuring soil erosion and degradation. At least, not according to the FAO.

"Data for Arable land are not meant to indicate the amount of land that is potentially cultivable."

The three main causes of soil degradation are overgrazing, deforestation, and mismanagement of arable land. We can do something about all three. Spreading demonstrably false claims about about catastrophic loss of arable land does nothing help. By spreading misinformation, the Grantham Centre for Sustainable Futures only fosters distrust by people who aren't fooled by their doomsday warnings.

If we want people to listen, a good place to start is with the truth. Not demonstrably false claims.

UPDATE: I heard back from a representative of the Grantham Centre, but I still have no idea where the number "33%" comes from.