From: dietz@cs.rochester.edu (Paul Dietz)
Subject: Re: Malthus was just ahead of his time
Organization: Computer Science Department University of Rochester
Date: Tue, 7 Apr 1992 04:07:48 GMT

In article <1992Apr5.221719.29752@zip.eecs.umich.edu> carnes@sparky.eecs.umich.edu (Richard Carnes) writes:
very >  Brown points out that new cropland and fresh water
> are becoming scarcer, the marginal returns on the use of fertilizer
> are diminishing, topsoil is eroding, forests are shrinking, rangelands
> are deteriorating, deserts are expanding, acid rain is falling,
> stratospheric ozone is being depleted, greenhouse gases are building
> up, the air is being polluted, and biological diversity is being lost,
> all of which factors have a negative effect on food production -- and
> the Panglossians are telling us not to worry, just look at the falling
> prices of the past, as if the future were bound to be a linear
> continuation of the past.

The point the boomsters make is that similar alarmist projections
have been made for decades, nay, for over a century, and have always
been wrong.  There is good reason to be skeptical about the
Cassandras.  To the extent that the Cassandras have made specific
forecasts about food production, they've tended to be wrong
(witness Ehrlich in TPB, Brown in the early 1980s).

There are reasons to be skeptical about the problems you mention:

  Acid rain: I visited the Black Forest in Germany last year, expecting
  to see evidence of acid damage.  I was told, in fact, that the rate
  of wood production in Germany is increasing, up 30%, due to the
  fertilizing effect of ... acid rain.  Nitric acid is a fertilizer.
  I also understand that 30-odd states in the US have some sulfur-deficient
  soils (sulfur being needed by plants in roughly the same quantity
  as phosphorus), and that sulfur fertilizer will become increasingly important
  as SOx is removed from powerplant emissions.

  Marginal returns of use of fertilizer: in the developed countries 
  the marginal returns may be small, but in many LDCs fertilizers the
  use fertilizer has not reached this point.  In the humid tropics,
  in particular, the impact of fertilizer, coupled with farming
  techniques that preserve soil against erosion, should be profound.

  Irrigation: in many developing countries, relatively little land is
  irrigated.  In 1980, only 1.7% of the arable land in Africa was under
  irrigation.

  Topsoil: methods are available for reducing or eliminating erosion.
  Already, 1/3 of the farmland in the US is being farmed with no-till
  or conservation tillage methods.

  Greenhouse gases: it is not obvious that this will have a negative
  impact on agriculture.  The growing season will be extended at
  higher lattitudes.  Increased CO2 will increase the productivity of
  C3 plants (including rice and wheat), and reduce evapotranspiration.

  Biodiversity: there are 20 major food crops.  Sure, millions of
  unknown species are being depleted, but the genetic heritage of
  those 20 crops (and scores of less important ones) are being
  carefully collected and stored at multiple repositories around the
  world.  The cost of doing this is not great; nor is the cost
  of collecting from closely related species.

  Ozone: the current depletions are worrisome, and certainly warrant the
  abandonment of CFCs and some related chemicals, but are in part
  due to catalysis on sulfuric acid droplets that will soon be gone.
  In any case, the increase in photosynthetic inhibition from
  decreased ozone is less than the increase in sunburning ability,
  since some photosynthesis inhibition occurs at longer wavelengths.

One recent event, the collapse of communism, should, in the long run,
increase the efficiency of agriculture in what was the Soviet Union.
Economist Lester Thurow warns us to not invest in upper US midwest
farmland, now that a large block of such land is hitting the world
market.

	Paul F. Dietz
	dietz@cs.rochester.edu