This page was emailed to a number of friends on 3rd June 2010 and their responses have been appended to this page.

Past/Current rice production
Rice production has been increasing exponentially, since 1950 the increase has been more than 350 percent. Most of this increase was the result of an increase in yields; the number of hectares increased only 40 percent during this period. The per-hectare yield increased more than 262 percent between 1950 and 1992.


Water requirements in rice production
Measuring rice production and water usage depends on the measurement taken, there are three types of water use:- transpiration - water used to cool the plant and drive up nutrients from roots to leaves evaporation - water leaves the crop from the soil underneath seepage/percolation - outflows of water from a field occur, flows from one field enter the groundwater or creeks and drains, from where other farmers may reuse the water to irrigate other fields.

An individual farmer may consider all three types of water use as the amount of water required to produce rice. For the purposes of this document we will take transpiration and evaporation (or evapotranspired) as the measure, seepage/percolation flows from one field enter the groundwater or creeks and drains, from where other farmers may reuse the water to irrigate other fields.

It takes an average of 1,432 litres of evapotranspired water to produce 1 kg of rough rice. This is roughly the same as the world-average water use of wheat, but higher than that of maize and barley. If we include seepage/percolation about 2,500 litres of water need to be supplied (by rainfall and/or irrigation) to a rice field to produce 1 kg of rough rice.

Click here for source

Rice crop challenges
There are three main factors which present the biggest challenges to providing the population with affordable rice

Pressures on fresh water


Population and rice production
As you would expect there is a correlation between population rises and the production of rice. The graph below illustrates this



Based on this close correlation we can predict future rice demand. In 2050 the world will need to produce approximately 25% more rice than in 2000.



Click here for population data source
Click here for rice data source

Global Warming
The IPCC have predicted that global average temperature increases between 0.15 °C and 0.3 °C per decade. By 2020 there will be a 1°C increase in global temperature which will result in a decline in rice grain yield

Climate Scenario	Temperature Change	Grain Yield (% deviation over normal scenario)
Extreme Weather	+2.0 °C	-8.4
Greater Warm	+1.5 °C	-8.2
Moderate Warm	+1.0 °C	-4.9
Slight Warm	+0.5 °C	-3.2
Normal Weather	Normal	6136 (kgha)

IPCC data source
Rice yield data source

Fresh water usage
With an increasing population there will be an increase in demand for fresh water.. The graph below illustrates projected fresh water demand. This graph makes allowance for better water management over the years.



Fresh water usage data source

The UN have a different view on water consumption, they predict global water withdrawal will increase faster. >. For the purposes of this document I have not used UN's figures as they do not appear to accommodate better water management.

UN water usage data source

Measuring water usage via evapotranspired,13% of all fresh water in the world is used in the production of rice.

Fresh water data source

India and China produce most of the worlds rice, India currently uses 40% of its available fresh water and China uses 5% this demand is due to double by 2025.

Current fresh water usage data source
Projected fresh water usage data source


Summary

Fresh global water supply will need to accommodate increased rice production and an additional (1432 litres x 40000000 kg = 57,280,000,000 Litres) 57,280,000,000 Litres of fresh water will be required. Fresh water demands will be felt most acutely in India and China which produce rice for the world.


Conclusion
Demand for rice will outstrip supply causing price of the commodity to rise, this will increase poverty or more efficient food sources will need to be cultivated.


Responses

Darren
Rice is the staple food of roughly 3 billion people, although centred mainly in Asia. For many of these people it provides over half of their entire calorie intake.
A couple of years ago, when rice crops were significantly reduced due to floods, major rice exporters such as Vietnam had to keep most of their production for the home market, causing prices to double and triple. It may be a bit of an annoyance to us when your box of Uncle Ben's goes up by a quid or two but when 80+% of your earnings go on food already this means that "luxuries" like meat have to be dropped from your diet.
What is needed is a second green revolution and GM is the answer. Forget the green-wellied, Prius driving, organic muesli-munching, middle-class, NIMBY, housewives whingeing on about "Frankenstein food". If yields aren't increased and water reliance reduced, millions of people will starve to death. Don't think it won't affect us, effects will spiral, food will be hoarded by nations that used to export it and that means shortages all round.
Water supplies will become far more valuable than oil, nations will go to war over it - if Ethiopia build dams on the Nile then countries up-river, Sudan and Egypt, lose out.
GM modification of rice - and other crops -can increase yield, resistance to pests and resilience to flooding, which in turn reduces the need for fertilizer and insecticide, a saving for both the farmer and the environment. Let's not be scared of using science. There a dozens of commercial varieties of rice, they don't each have their own wild ancestor. Just as all our breeds of dog have been manufactured by man by cross-breeding wild varieties of dog, wolves etc, so it is with all our cereal crops.
And how do you cross breed plants? Literally by tapping the flowers of each species together to exchange pollen. Just as you can't predict which maternal or paternal traits a child may inherit, so it is with this method. In one famous case as small, hardy potato variety was crossed with a large, delicate one. The result was a large, hardy potato, but one that contained cacogens that had not been present in either parent species. With GM we are in control of which traits of each species are crossed and so cancerous spuds are not just less likely but should also be weeded out if they do occur. The bio-luminescence of deep-sea fish has been successfully transplanted into mice. Whilst glow-in-the-dark mice are of little practical use, they don't suffer any ill-effects either.
But for those who like organic farming, in some Chinese hillside paddy fields which consist of a series of terraced, small pools, the farmers also keep fish in the paddy. Not only does this provide a second source of food/crop but the fish predate many of the pests that would normally attack the rice.
So in conclusion, barring a major bird-flu pandemic, the world population, fast approaching 7 billion already, is set to rise to 9 billion in the next 10 years. Any form of human intervention to prevent this is unlikely, unless China conquers the world soon. That is simply too many people for us to feed. Worldwide for the last ten consecutive years we have had to turn to our food reserves to feed everyone, as annual production was not enough. Whilst reserves have been used before, a ten year run is unprecedented.
Scientists have two options, create hardier, higher-yield food or invent a disease that targets smelly foreigners who talk funny and don't share our freedom-loving, liberal principles.
On the bright side, most of you reading this will be dead before this situation gets too bad. Sweet dreams.
PS If anyone has ideas for a game showing featuring luminous mice, please let me know.