In doing research on the issue of desertification (aka land degradation) I keep running across the same basic sentence but no source or detail to support or clarify it:

"Arable land loss is estimated to be at 30 to 35 times the historical rate."

Can anyone help me find a source that specifies this "historical rate"? Over what length of time is history being measured? What is the geographic scope of this data?

Failing a specific source for this quote, can anyone provide a reliable source for the data subject the quote refers to (i.e. a long term track record of desertification)?

  • $\begingroup$ I read the statement to mean land that was formerly in production being taken out of production because of environmental factors - not net loss that considers new land being put into production. That is useful in considering the social impacts of no longer being able to farm, but the comparison to long-term 'historic" trends is problematic. If a lot of land was put into production 20 years ago and farmed intensively and unsustainably then you would get an increase in land loss now due to the prior land increase. $\endgroup$
    – haresfur
    Oct 12 '15 at 2:43
  • $\begingroup$ I have awarded the bounty to Aabaakawad. Frankly I like userLTK's answer best but Aabaakawad did come closest to answering what I asked for: "a specific source for this quote", which userLTK said he was unable to find. My ultimate goal was to prove or disprove this statement and it would seem that noone was actually able to assist with that, short of my now knowing I could theoretically contact Klaus Töpfer and ask him for his sources. $\endgroup$
    – O.M.Y.
    Oct 17 '15 at 9:57
  • $\begingroup$ I like the @userLTK answer too. $\endgroup$
    – Eubie Drew
    Oct 17 '15 at 14:09
  • $\begingroup$ @O.M.Y. found the full report ... in Norway. grida.no/publications/other/geo2000 $\endgroup$
    – Eubie Drew
    Oct 17 '15 at 14:44
  • $\begingroup$ Thank you Aabaakawad, I'll look through it and try to see if I can isolate the data that Toepfer based his statement on. I suspect this is a hefty report, eh? :) Thanks again. $\endgroup$
    – O.M.Y.
    Oct 17 '15 at 16:59

No context is given, but at face value this is a meaningless quotation. Globally there is a net increase in arable land from close to zero about 8000 years ago, to the current maximum of just over 40% of the gross biological productivity of the planet. 'Arable land loss' can refer to the land lost to urbanization, salinization or desertification. One might also make a distinction about agricultural land lost to hydrologic intervention, as in the decreasing flows of the Amu Darya, and Sur Darya in Central Asia. In addition, over the coming decades we will begin to see agricultural land lost to climate change impacts. No single assessment of the 'historical rate' of arable land loss is meaningful. One has to evaluate the various processes separately, and then aggregate them at regional level.

  • $\begingroup$ Gordon, I agree it is an incredibly vague comment yet I have found this claim repeated over and over again on many websites and articles about desertification/land degredation. I am hoping to find some sort of source for the data to be able to give (or eliminate) validity and context. $\endgroup$
    – O.M.Y.
    Oct 1 '15 at 11:58
  • $\begingroup$ Many a quote attains the status of 'fact' simply through repetition, but that doesn't mean it is valid or worthwhile pursuing. If you can't trace the original source (and neither can I) my advice is to give your quote under "Anon", and then run with your own well argued analysis. $\endgroup$ Oct 1 '15 at 12:28
  • $\begingroup$ I generally would agree with you, but considering this "factoid" was found in a brochure from the United Nations Convention to Combat Desertification I would really like to nail this down as fact or fiction. $\endgroup$
    – O.M.Y.
    Oct 1 '15 at 22:33
  • $\begingroup$ When it comes to scientific statements I warn against giving too much credence to UN agencies. They sponsor science, and promote scientific conventions etc., but, like the IPCC, The UN convention to combat desertification is primarily a bureaucracy. For example, Monique Barbut, the general secretary of the UNCCD is a diplomat, not a scientist. I once worked for the UNDP as a chief technical advisor, and can report that these agencies are image obsessed PC entities for which rigorous science is not their highest agenda. $\endgroup$ Oct 10 '15 at 11:20
  • $\begingroup$ @GordonStanger I disagree with you on the IPCC. They largely independently operated and they have a very strong science focus. They also get attacked, often, by people with an agenda and they are unfairly given a negative view by a lot of people. Now, I can't speak for the UNCCD, as I don't know their scientific approach or other UN organizations but the IPCC, and I've read a fair bit on this subject, is very good. $\endgroup$
    – userLTK
    Oct 10 '15 at 11:35

It's a curious question.

I agree with Gordon Stranger, without context, (and a mention of some link to peer reviewed research, or at least, some kind of measurement), it's pretty meaningless.

I did a a google search and checked links with books.google.com in them to search for a source but everything refers back to UNCCD and UNCCD, as far as I read their reports, never explains or provides a source for that sentence.

Google Search for books

List of reports I went through a few - no luck.

I did find this:

enter image description here

Source: but the problem is, they're using a different criteria than you. Forest can be cleared to create new arable land, so that's why they show an increase when UNCCD shows a decrease. If you combine this chart with deforestation, you might have something a little bit close to what you're looking for.

In the US, (edit) farm land (not necessarily arable land) has decreased but food production has increased due to improved technology, fertilizer and all that good stuff.



Bad farming methods leads to loss of arable land much faster than good methods. Here's a good answer on the dustbowl that you might find interesting and even early societies, thousands of years ago, they lost arable land cause there were processes that happened that they didn't understand, explained more here.

Environmental effects, mostly tend to be cyclical and are probably harder to measure outside of human effects. California might have a big drought one year and have a great growing season the next. The droughts we experience don't make the land permanently not arable, just for 1 growing season. Floods - might have a bigger effect if they wash away good land but they can also have the opposite effect, depositing rich silts adding nutrients to the soil. Over long term, climate change can affect arable land, for example, 13,000 years ago / give or take, the Sahara was a rich forest with huge lakes (We know this by fossils that remain there) and that may be a cycle that comes and goes with every orbital tilt of the Earth. During the last ice age, much land was covered by ice, but lower sea levels left lots of rich valleys that are now covered by water. The story of Noah and Gilgamesh are thought to be based on the flooding of one such fertile valley, caused in part by the end of the ice age and rising water.

So, at least from an environmental perspective, it's a complicated question with lots of moving parts. Hope that helps, though I'm not sure it does. I was curious about what you asked so I looked into it a bit.


EDIT -- Found the full report ... in Norway.

The quote you are trying to source was an oft repeated (1999-2002) talking point by Klaus Toepfer (Töpfer), head of UNEP. The oldest instance I can find is in London, 1999.

The rate at which arable land is being lost is increasing and is currently 30-35 times the historical rate. Only about one and a half billion hectares remain out of the original three and a half billion. The loss of potential productivity due to soil erosion world wide is estimated to be equivalent to some 20 million tons of grain per year or 1% of global production.

Other later versions of his quote form a larger paragraph with one or two preceding sentences about soil loss in Africa, so the scope may not in fact be global. He and several others sometimes credit the UNEP Global Environment Outlook 2000 (GEO-2000) report, then link to this overview. I have electronically combed through the above overview and found nothing and I can not find a full report online. There are many alleged links, but they all go to the overview. FOUND IT HERE.

  • $\begingroup$ I think it's Klaus Töpfer $\endgroup$
    – mart
    Oct 19 '15 at 6:09

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