How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Atmospheric CO2 Enrichment:
Just What the Food Doctor Ordered!

Volume 6, Number 15: 9 April 2003

Over the last four decades of the 20th century, per capita world food production rose by approximately 25% (FAO, 2000).  Nevertheless, as noted by Pretty et al. (2003), "food poverty persists."  In fact, out of the six billion people currently inhabiting the planet, they say some 800 million lack adequate access to food.

Writing as advocates for these undernourished individuals -- for whom more food would be a godsend -- Pretty et al. suggest there are "three strategic options for agricultural development if food supply is to be increased."

The first of these options, in their words, is to "expand the area of agriculture, by converting new lands to agriculture."  However, as they rightly note, this option results in "losses of ecosystem services from forests, grasslands and other areas of important biodiversity," as they are transferred from the realm of nature to the domain of man.  Hence, this solution to the problem of world food security is untenable, unless, of course, we care nothing about maintaining what little of the natural world yet remains.

The second of Pretty et al.'s strategic options is to "increase per hectare production in agricultural exporting countries," so as to not take additional land from nature to feed mankind.  However, as they again rightly note, this option means that food "must be transferred or sold to those who need it."  And those who need it, in the words of Pretty et al., are those "whose very poverty excludes these possibilities," in that they can't afford to pay for the food they need.

We come, then, to the last of Pretty et al.'s three options, which is to "increase total farm productivity in developing countries which most need the food."  This option is essentially the same as option two, only applied to parts of the world where farmers are constrained by their poverty to use "low cost and locally available technologies and inputs."

The rest of Pretty et al.'s paper describes a number of well-conceived programs designed to achieve this goal and lists their successes to date.  We describe another such program (perhaps we should call it a phenomenon) that was neither conceived nor planned by anyone, but which has also had many successes and is destined to have many more in the years and decades to come.

The phenomenon to which we refer is the enriching of the air with carbon dioxide that has come about as a consequence of the development and progression of the Industrial Revolution.  Because of the prodigious and ever-increasing quantities of CO2 that have been released to the atmosphere by the burning of the coal, gas and oil that has fueled this incredible human enterprise, the air's CO2 concentration has risen -- without any overt planning on the part of man -- from a pre-industrial value of approximately 275 ppm to a current concentration on the order of 375 ppm.

What has this extra 100 ppm of CO2 done for us to date in the way of increasing farm productivity?  In our Editorial of 11 July 2001, we describe experimental work based on the studies of Mayeux et al. (1997) and Idso and Idso (2000) that suggest its aerial fertilization effect has led to mean yield increases of approximately 70% for C3 cereals, 28% for C4 cereals, 33% for fruits and melons, 62% for legumes, 67% for root and tuber crops, and 51% for vegetables.  Although less than the 93% increase in per-hectare food production brought about by the many low-cost, low-tech projects assessed by Pretty et al., these historical CO2-induced yield increases have nevertheless been both substantial and important.  What is more, they were totally unplanned by man, coming about solely as a result of humanity's flooding of the air with CO2.  In addition, this unanticipated but welcome godsend is not just a relic of the past; for, if we will let it, it will grow even stronger in the years and decades ahead, as the air's CO2 content continues to rise.

Another positive aspect of the technologies and inputs employed in the projects studied by Pretty et al. is that "they make the best use of nature's goods and services whilst not damaging these assets."  This virtue is best appreciated when compared to some of the negative side effects of what Pretty et al. call "industrialized agriculture," where they say "environmental and health problems associated with industrialized agriculture have been well documented," citing the works of Conway and Pretty (1991), EEA (1998) and Wood et al. (2000).  Within this context, we merely note that not only does atmospheric CO2 enrichment not hurt "nature's goods and services," it actually helps them, making natural vegetation -- and field crops too -- more resistant to the deleterious effects of gaseous air pollution, soil salinity, water stress and high temperatures (Idso and Idso, 1994).

Speaking of agricultural systems that emphasize the principles employed in the programs they analyzed -- which are shared, if not bettered, by enriching the air with CO2 -- Pretty et al. say they "contribute to a range of valued public goods, such as clean water, wildlife, carbon sequestration in soils, flood protection, groundwater recharge, and landscape amenity value."  With such side effects as these, the ongoing rise in the atmosphere's CO2 concentration would appear to be just the medicine the world needs to sustain its natural ecosystems while helping humanity to adequately feed its growing numbers.

Sherwood, Keith and Craig Idso

Conway, G.R. and Pretty, J.N.  1991.  Unwelcome Harvest: Agriculture and Pollution.  Earthscan, London, UK.

EEA.  1998.  Europe's Environment: The Second Assessment.  European Environment Agency, Copenhagen, Denmark.

FAO.  2000.  Agriculture: Towards 2015/30.  Global Perspective Studies Unit, Food and Agriculture Organization, Rome, Italy.

Idso, C.D. and Idso, K.E.  2000.  Forecasting world food supplies: The impact of the rising atmospheric CO2 concentration.  Technology 7S: 33-55.

Idso, K.E. and Idso, S.B.  1994.  Plant responses to atmospheric CO2 enrichment in the face of environmental constraints: a review of the past 10 years' research.  Agricultural and Forest Meteorology 69: 153-203.

Mayeux, H.S., Johnson, H.B., Polley, H.W. and Malone, S.R.  1997.  Yield of wheat across a subambient carbon dioxide gradient.  Global Change Biology 3: 269-278.

Pretty, J.N., Morison, J.I.L. and Hine, R.E.  2003.  Reducing food poverty by increasing agricultural sustainability in developing countries.  Agriculture, Ecosystems and Environment 95: 217-234.

Wood, S., Sebastien, K. and Scherr, S.J.  2000.  Pilot Analysis of Global Ecosystems.  IFPRI and WRI, Washington, DC.