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By Charles Rhodes, P.Eng., Ph.D.

From an agricultural perspective the fundamental problem with global warming is that it increases the soil moisture evaporation rate and the plant moisture transpiration rate without causing a corresponding increase in the average precipitation.

It is shown herein that as the atmospheric carbon dioxide concentration increases the average amount of irrigation required per unit area of farm land under cultivation increases. Since the total fresh water supply is limited by ocean evaporation, which is independent of the atmospheric CO2 concentration, as the atmospheric carbon dioxide concentration increases the total land area under cultivation decreases. Since the agricultural carbohydrate production is approximately proportional to the land area under cultivation, the net result is that as the atmospheric carbon dioxide concentration increases the world wide agricultural carbohydrate production decreases.

Increasing the atmospheric CO2 concentration by a factor of two increases the average fresh water requirement for irrigation of farm land under cultivation by about .1446 m / annum. As the atmospheric CO2 concentration increases this requirement for extra irrigation will substantially reduce farm land under cultivation, which will contribute to world wide starvation.

On the web page titled Radiation Physics it was found that the average extra fresh water requirement for irrigation in m / year caused by Global Warming is given by:
dHa /(Ro Hv) = (dTa / Ta) Ho (1 - Fr) / (Ro Hv)
dHa = increase in net heat absorption per unit area per unit time (joules / m^2-year)
Ro = density of water (1000 kg / m^3)
Hv = latent heat of vaporization of water (2270 kJ / kg)
dTa = increase in annual average temperature
Ta = average absolute emission temperature
Ho = solar irradiance (1367 watts / m^2)
Fr = planetary albedo (.297)

On the web page titled Global Warming it was found that when the atmospheric CO2 concentration is doubled the average dry ground temperature increases by 2.923 degrees C.

Thus to a good approximation the increase in irrigation requirements when the atmospheric CO2 concentration is doubled is:
dHa /(Ro Hv) = (2.923 / 270) (1367 W / m^2) (.703) (1 J / s-W) (1 kJ / 1000 J)(3600 s / h) (8766 h / year) / ((1000 kg / m^3) (2270 kJ / kg))
= [(2.923 / 270) (1.367 X .703 X 3.6 X 8.766) / 2.270] m / year
= .1446 m / year

The water vapor from this additional irrigation condenses in the upper atmosphere releasing its latent heat of fusion as infrared radiation. If there were no winds the condensate would fall back to Earth's surface, displacing the extra irrigation. However, in reality wind distributes the cloud particles around the Earth, so the probability of cloud condensate falling over land is:
1 - (Ao / As)
= 1 - .708
= .292
Ao = ocean area
As = total surface area of the Earth.
The probability of this cloud condensate falling over cultivated land is even smaller, so the average contribution to the extra irrigation arising from cloud condensate due to other extra irrigation is relatively small.

In the USA there are about:
941.2 X 10^6 acres farm land X 1 mi^2 / 640 acres X (1.61 km / mi)^2
= 3.812 X 10^6 km^2 farm land under cultivation
= 3.812 X 10^12 m^2 farm land under cultivation.

The total area of the USA is 9.83 X 10^6 km^2

The probability of condensate from extra irrigation contributing to other required extra irrigation is:
.292 X (3.812 X 10^6 km^2) / (9.83 X 10^6 km^2)
= .113

In Canada this probability is very much smaller.

In the USA the extra irrigation that will be required by farmland to offset global warming, after the atmospheric CO2 concentration has doubled, is about:
(3.812 X 10^12 m^2)(.1446 m / year)( 1 - .113)(1 year / 8766 h)(1 h / 3600 s)
= .015493 X 10^6 m^3 / s
=15,493 m^3 / s

By comparison, the total Niagara river flow downstream from Niagara falls and the associated power stations is about:
5,800 m^3 / s.
Hence, maintaining US farm production while doubling the atmospheric CO2 concentration would require:
(15,493 m^3/s) / (5,800 m^3/s) = 2.67 additional Niagara size rivers, that simply don't exist.

The USA is already experiencing severe fresh water shortages and consequently the farm area under cultivation is gradually shrinking. Even if the Niagara River was blocked off and an equal flow of fresh water was diverted from the Great Lakes into the USA for irrigation, this flow would meet less than 37% of the projected near term irrigation problem. The simple reality is that to maintain farm area under cultivation and hence agricultural production it is essential that all electricity utilities stop burning fossil fuels and that these electricity utilities also generate enough electricity by non-fossil means to almost completely displace fossil fuels for primary energy and heat production.

Assume that the average annual rainfall in major agricultural areas is about 1.0 m water/ year. On that basis when the atmospheric CO2 concentration has doubled the world will have lost about 14.46% of its former agricultural production capacity.
Quite bluntly, the effect of this loss of agricultural output is that about 14.46% of the world's present population:
.1446 X 6.5 billion people
= .94 billion people
= .94 X 10^9 people
will face death by starvation
, even before natural population growth and the effects of biofuel production on the world food supply are taken into account.

With a population of 12.6 million people and with per capita fossil CO2 emissions four times the world average, Ontario's fraction of the excess atmospheric CO2 problem is:
(12.6 million / 6.5 billion) X 4 = 7.75 X 10^-3.
The number of projected human starvation deaths directly attributable to continuation of Ontario's present CO2 emissions is reasonably projected to be:
7.75 X 10^-3 X .94 X 10^9 deaths = 7.285 million human starvation deaths.

A policy of continued fossil fuel consumption in Ontario is comparable to the worst policies of Nazi Germany.

1. In North America and elsewhere all levels of government have been unwilling to face the full realities of carbon dioxide induced climate change.
2. The first reality is that stabilizing the atmospheric CO2 concentration at its 1990 value requires reducing world wide fossil CO2 emissions to 47.8% of 2004 world wide fossil CO2 emissions. It will likely require wartime like measures to achieve and sustain that CO2 emission reduction. The per capita fossil CO2 emission reduction required in Canada and the USA, in order to match the required per capita CO2 emissions for other countries, is about 89%.
3. The second reality is that there must be a major increase in non-fossil fuel electricity generation and in nuclear heat production to displace fossil fuels for: vehicle propulsion, space heating, domestic hot water heating and production of biofuels.
4. The third reality is that due to global warming there will be a major reduction in total agricultural carbohydrate output until the excess atmospheric CO2 concentration decays. The half life of the excess CO2 in the atmosphere is about 25 years. Until the excess atmospheric CO2 concentration decays the total land area under cultivation and hence the total agricultural carbohydrate output will be significantly reduced.
5. Much of the world's crops are presently grown on river deltas which will likely eventually be innundated by the rising sea level or made too salty to support food crops.
6. Much of the world's crops are presently grown on land that relies on mountain snowpacks, lakes or aquifers for summer irrigation. The snow packs, lakes and aquifers are being wiped out by increasing evaporation.
7. Much of the remaining arable land will be taken over by crops that are dedicated to production of biofuels.
8. Hence, the amount of arable land available for food crops and livestock will rapidly decrease.
9. With free markets, those who cannot pay more for food carbohydrate than synthetic liquid fuel producers are willing to pay for feedstock carbohydrate will simply starve to death.
10. Each nation may have to adjust its tax and duty system to give food production for internal consumption priority over food exports and biofuel production.
11. The more governments delay dealing with these important climate change related issues, the more acute the problems will become.
12. The fourth reality is that if mankind does not reduce its population in an orderly way via birth control, natural selection in the form of famine, disease or war will relentlessly implement the population reduction process.
13. The fifth reality is that continuing use of fossil fuels to support the excess population is not viable. Use of fossil fuels now has the effect of increasing future energy requirements for air conditioning and increasing future fresh water requirements for irrigation, further aggravating the shortages of both non-fossil fuel energy and arable land.
14. There are people who mistakenly think that a warmer climate in Canada and northern Asia would be more desirable for agriculture. The sixth reality is that agriculture relies on photosynthesis to form carbohydrates. Increasing the average temperature does not increase the number of solar photons that are available for performing photosynthesis.
15. The crisis of climate change is quickly evolving into a crisis of population, arable land and irrigation. The ability of nations to survive depends on their ability to feed their populations.
16. The people most immediately at risk are those that rely on donations of surplus food. When farmers can make more money from production of biofuel feedstock than from production of surplus food, there will be no surplus food to donate.
17. Continuing use of fossil fuels for primary energy generation will reduce the Earth's population via starvation and starvation related conflict. The only route to relief is generation of really large amounts of non-fossil fuel energy in order to displace fossil fuels. Practical matching of non-fossil fuel electricity generation to the electricity load requires large amounts of energy storage. Financially enabling energy storage requires electricity rates based on peak kVA, not cumulative kWh.


This web page last updated January 3, 2016.

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