Emmott’s Wildly Wonky Chocolate Factoid Factory

(Guest Post by Alex Cull)

Amongst all the alarming factoids relating to water that appear in Prof. Steve Emmott’s play “Ten Billion” (and possibly also in his forthcoming book), few can have been more alarming than the one about chocolate, i.e., that it takes 27,000 litres of water to produce one bar of the stuff.

Quite a few reviewers of the play refer to it. Journalist Matt Trueman writes: “Essentially, Emmott frames the whole system in economic terms, to show that as a species we are living on massive credit. A single bar of chocolate, for example, requires 27,000 litres of water for its production. By the time a car has been made, it has already had a significant enough impact on the environment that driving it is negligible. These resources cost the planet, but it’s future generations that will pick up the bill. Our current mode of existence is unsustainable. And, short of behavioural or political changes so radical that they’re unthinkable, it will continue to be so until the end, because we are a species in denial, failing to investigate the possible slim, slim hopes for averting the impending crisis.” [1]

The tone of the play, and of the reviews, is one of shock and horrified disbelief – 27,000 litres of our precious, life-giving water is being squandered every time a chocolate bar is produced. Wicked waste! No wonder we’re doomed.

As with beef (see my previous post) two basic questions we can ask are:

1) Is this 27,000 litres/choc bar figure accurate?

2) Does it matter, anyway?

So, firstly, where does the figure of 27,000 litres come from? Strangely, I’ve found this number difficult to track to its source. It’s found on quite a few websites, notably Urban Times [2] but these don’t tell us how the figure is derived. However, Urban Times links to a website that you will be familiar with, from my post about beef – waterfootprint.org. [3]

Locate chocolate in the Product Gallery on waterfootprint.org, and you will immediately see that the figure there is actually 17,196 litres per kilogram. Chocolate is made from cocoa paste, which is reckoned to have a water footprint of 24,000 litres/kilogram, but is also made from cane sugar at 1800 litres/kilogram, so the finished product comes out at a global average of about 17,000 litres/kilogram.

It’s very different to what Prof. Emmott appears to have been saying. This is what I think might have happened.

1) Water engineers Mekonnen and Hoekstra produced their report “The green, blue and grey water footprint of crops and derived crop products” in 2011 [4], which gives a figure of 17,196 litres of water to produce one kilogram of chocolate, and which is available on the waterfootprint.org website.

2) Landscape architect Claire Thirlwall wrote an article for Urban Times about water use in the chocolate industry, also in 2011. It’s actually a balanced and sensible article, but what may have occurred (my apologies to Claire if this is not the case) is she saw “17,000” as “27,000”, which is why she wrote “… that bar of chocolate needs a staggering 27,000 litres of water per kilo.”

3) Professor of Computational Science Steve Emmott was gathering material in late 2011 or early 2012 for his upcoming play “Ten Billion” and read the Urban Times article. What may have occurred (my apologies to Steve if this is not the case) is he saw “that bar of chocolate needs a staggering 27,000 litres of water”, without noticing the “per kilo” at the end.

And that is possibly how “Ten Billion” ended up with the remarkable and also horribly inflated number of 27,000 litres per chocolate bar.

The other basic question is: does it matter, anyway? As with grass-fed beef, the answer is: no, not really. The water that goes to produce chocolate is, according to waterfootprint.org, 98% green, 1% blue and 1% grey. The reason for that is not hard to work out – much of it comes from places like Ghana, which enjoy vast amounts of rainfall each year. If cocoa beans were not cultivated there, the water would simply go to nourish other plants in the rain forest and continue on its path around the hydrological cycle. Ghana – as Claire Thirlwall notes in her Urban Times article – scores a very relaxed 0% on the Water Stress Index. [5]

The fact that a tiny part of Ghana’s bounty of rainwater (a natural, free, renewable resource) is diverted into making chocolate bars, is neither here nor there in the grand scheme of things. It doesn’t exactly “cost the planet”, and it doesn’t hurt the Ghanaians, whose economy is set to grow something like 5.5% this year, which will raise living standards and also, hopefully, improve working conditions there. Nothing is actually going to waste.

Which makes it all the more ironical to find a report into food waste (The water and carbon footprint of household food and drink waste in the UK, published in 2011 jointly by WRAP and WWF) which specifically mentions chocolate as one of the “top two products in the list of water footprint of household food waste” (the other worst offender, you will not be surprised to learn, is beef.) [6]

“Chocolate is another example of contrasting impacts. The quantity of chocolate thrown away is relatively small (24,000 tonnes of chocolate bars plus 7,000 tonnes in hot chocolate). Its contribution to the carbon footprint of food and drink waste is also small (117,000 tonnes CO2 equivalent), yet it significantly contributes to the water footprint of food waste, accounting for over 750 million cubic metres of water.”

If it weren’t so laughable, it would be quite infuriating to receive stern lectures from WWF about your “water footprint of food waste” based on such ridiculously shaky foundations. Enough to make you boiling mad, perhaps, or “like water for chocolate”, as the Spanish expression goes.

In a lighter vein, I’ll leave you with something that could be called the choco-hydrological cycle (or maybe the hydro-chocological cycle, I can’t decide which.) You might like to hum the Circle of Life theme from Disney’s “The Lion King”, while reading this – just a thought.

1) Rain falls from the skies in equatorial Africa, nourishing all the plants in the tropical rain forest ecosystem.

2) Some of that rainfall goes to nourish cocoa trees, cultivated by enterprising people in Ghana.

3) The cocoa is turned into chocolate – Mekonnen and Hoekstra reckon it takes, on average, about 17,000 litres of water to make a kilogram.

4) An internet article inflates that 17,000 litres to 27,000 litres of water per kilogram of chocolate.

5) Prof. Emmott then multiplies this by a factor of 10 to arrive at an incredible 27,000 litres of water per chocolate bar.

6) At the performances of “Ten Billion”, audiences are shocked and horrified by this huge figure.

7) Reviewers mention it in their reviews – more people read them and are shocked and horrified.

8) Overcome by shock and horror at the information, people rush out to buy and consume great quantities of comfort food, especially chocolate.

9) The chocolate is digested, nature takes its course and all residual water contained in the chocolate is ultimately returned to the biosphere.

10) The cycle begins all over again.


[1] http://matttrueman.co.uk/2012/08/review-ten-billion-royal-court.html

[2] http://urbantimes.co/magazine/2011/11/is-water-use-in-the-chocolate-industry-excessive/

[3] http://www.waterfootprint.org/?page=files/home

[4] http://www.waterfootprint.org/Reports/Mekonnen-Hoekstra-2011-WaterFootprintCrops.pdf

[5] http://www.epi2010.yale.edu/Countries/Ghana

[6] http://www.waterfootprint.org/Reports/Water-and-carbon-footprint-food-and-drink-waste-UK-2011.pdf

About Geoff Chambers

Retired illustrator (children's magazines, religious education textbooks, an Encyclopaedia of Christianity, gay contact and female fitness magazines, pornographic strip cartoons etc.) Retired lecturer in English and History of Art in a French University; ardent blogger on climate hysteria, banned five times from the Guardian and twice from the Conversation. Now blogging at Cliscep.com
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7 Responses to Emmott’s Wildly Wonky Chocolate Factoid Factory

  1. … and he’s a professor?

  2. steveta_uk says:

    This is the truely shocking part, that made me feel almost ill at the very idea:

    THe quantity of chocolate thrown away is relatively small (24,000 tonnes of chocolate bars plus 7,000 tonnes in hot chocolate).

    What possible reason is there to throw away 24,000 tonnes of chocolate bars?

    Read it and weep, Jo Brand.

  3. Mark P says:

    Steveta, 24,000 tonnes works out at 400 g per person, per year assuming the UK. Not a lot.

    I personally have been party to several tonnes of chocolate being discarded. An entire container leaked salt water in transit. Sorting out the good from the bad would have cost more than the container was worth. Insurance paid anyway.

    Add in spoilage of all sorts and you can quickly get to half a kilo per person.

  4. Dodgy Geezer says:

    It’s not only chocolate.

    The new green frightener seems to be ‘water-waste’. The line taken is that every use of water (apart from directly drinking it) is ‘waste’, and, because water is sometimes used in large quantities, huge figures are bandied about.

    Someone needs to start a viral campaign to remind people that NO use of water is waste. I can leave my bath taps overflowing for a week, and none of that water is ‘wasted’ – it is all back in the water cycle for immediate re-use. What I HAVE wasted is the cost of collecting and purifying it – NOT the water. And these costs are so small that they should hardly need to be considered.

    Note that if water processing costs are cheap there is no need to worry about leaks or waste. You only need to worry about these if water is expensive. The green proposal to ‘cut wastage’ will only work if water is priced more like gold dust. And that, of course, is their aim…

  5. manicbeancounter says:

    The problem here is the partly the difference between gross and net.
    In accountancy it is easy. In business the gross values are sales and costs. The net value is the profit or loss. In Government the gross values are tax receipts and expenditure. The net value is the surplus or deficit.
    The gross water requirement to produce a kilo of chocolate is 17,000 litres per kg. The net loss is maybe 5 litres.
    In economics, there is a concept called opportunity cost. What needs to be foregone. As you point out, growing the beans in a rainforest has zero opportunity cost.

    Another example if the food miles issue. Should we all go to the local farmers markets, so save the environment. If I went to get a 2kg joint of lamb from a farmers market 20 miles away, plus the distance of 100 miles the meat travelled from farm to abattoir to butcher to market, then the argument goes that this would be a lot better for the environment than the getting a 2kg joint of New Zealand lamb travelling 12,000 miles. In fact 100 times better. assuming all forms of transport travel empty one way.
    But if the choice was buy the NZ lamb on a weekly trip to the supermarket, and the farmer’s market butcher only sold 100kg of meat on his 20 mile round-trip to the farmer’s market, then the fuel consumed in travelling by me and the butcher might be more than the total fuel (including refrigeration) of transporting the lamb by ship and road from New Zealand. It certainly would be if I drove a 20mpg Cheshire Tractor, rather than my 60mpg diesel.

  6. Mark P says:

    The key feature most people notice about the UK is its dampness. Trying to frighten them into worrying about “water waste” is never going to work when the stuff literally won’t stop falling from the sky.

    I live in NZ which is ever wetter, albeit we don’t really do drizzle. About 20 years back when I had just moved to Auckland we had a “drought”. I know it was a drought because all the media kept saying it was. The fact that it rained lightly nearly every day didn’t stop them calling it a drought! What we actually had was a longish period when it didn’t rain enough in the hills for the water to fill the reservoirs, so the city was very short on drinking water.

    So focused did they become on the lack of purified water that some people didn’t actually notice that it kept raining! The alarmists started talking about how we could expect many more of these droughts. How we would have to change our gardens, for example, to put in drought resistant plants. Never mind that not a plant in my garden died from water loss.

    The city water people weren’t so stupid. They just went and put a pipe in from the Waikato river, as cover for long dry periods.

    So earlier this year when we did actually have a real drought, with no water falling for months on end, there was no water shortage at all.

  7. alexjc38 says:

    Great comments, and I’d have jumped in sooner to respond but have been horribly busy over the last few days.

    Just to add that behind the scarcity mentality relating to water appears to lie the idea of freshwater use as a fixed “planetary boundary” (it’s one of the nine “non-negotiable” limits on human activity that were drawn up by Johan Rockström and which have been seemingly adopted wholesale by the UN.) In this model, there’s a global limit to the amount of (blue) water the human race should be using (i.e., “Hold consumption to less that 4,000 cubic kilometers per year of runoff.”)

    The idea seems to be that people who don’t have enough water should be helped to have more of it, through irrigation, etc., which is fair enough, but the model seems to imply that there are also people (maybe living on the other side of the world) who use “too much” and whose demand should be managed accordingly.

    Having a fixed “planetary boundary” for water use makes the whole thing look like a zero-sum game, which it basically isn’t.

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