The volume of waste produced by an economy is a good index of its impact on the natural world. Everything we consume starts by being extracted from the earth’s crust or soil, is then processed to make it useful to us and eventually turns into waste. Whether it is an iPad, a hamburger or a Volkwagen Golf, our goods all ultimately come from the ground. After delivery a service to us, everything is discarded and becomes rubbish, collected by the local council every week or so.

The conventional view of the world is that growth in GDP always takes the form of increased consumption of physical goods. As we get richer, we’re told,  we buy more stuff. For a long while this simplification was broadly correct. A large fraction of the extra income that households gained in wealthy countries between 1960 and about 2000 was spent on things you could touch. We bought cars, washing machines, more clothes, TVs and garden furniture. As the Oxford sociologist Jonathan Gershuny points out, the second half of the 20^th century is often portrayed as the beginning of the ‘service’ economy but it is characterised more accurately as the period when household life became mechanised. Households acquired a large number of heavy machines.

That era ended in advanced economies a decade or so ago. In the UK, most indices of physical consumption show a decline from around 2002, a point I have called ‘peak stuff’. That decline will continue. We have the machines we need and the ones we have last longer (compare the lifespan of a car today with one a generation ago for example), and are generally lighter and easier to recycle. I know it is difficult to believe, but we eat less, use less water and travel fewer kilometres each year. Broadly speaking, we are slowly replacing the consumption of physical goods with the pursuit of pleasurable experiences. Each year, a larger fraction of our income goes on visiting the David Hockney exhibition, attending a Manchester United football match or paying for out Netflix subscription.

We see this in the amount of waste we throw away. Waste production per person in the UK peaked at around 520 kg a year in the year to March 2002. The latest two quarters figures are fifteen per cent below that level. The lastest quarterly figures suggest a figure of about 443 kg. The decline from year to year isn’t smooth but is probably getting steeper. (Please note that the last two columns in the chart below are for the most recent quarters. The apparent slackening in the rate of decline is an artefact of the way DEFRA draws the chart). Today’s waste levels are well below the levels of 1996/7. By contrast, in the period from 1997 to today, inflation-adjusted GDP has risen by over a third. (This isn’t quite a fair comparison since the UK population has also increased during the last fifteen years). Household rubbish is actually a small fraction of the total flow of waste out of the economy. Construction waste is far more important but this is also falling sharply. All in all, we produce far less rubbish than we did a couple of decades ago.

The probable implication? In contrast to what the Royal Society says, growth may be good for the environment. We waste less and are prepared to devote more cash to ecological protection. Technology improvements mean things last longer and use fewer physical resources to make.  Regretfully, I have to say that the world’s most prestigious scientific institution should spend more time checking its facts. As people get richer, they don’t buy, and then dispose of,  more goods. As England shows, more GDP doesn’t mean more waste.

Source: DEFRA, Local Authority Collected Waste for England, May 2012

(http://www.defra.gov.uk/statistics/environment/waste/wrfg22-wrmswqtr/)

Over the past four decades, a growing fraction of world food supply has been diverted to meat animals. Nevertheless, the typical person has access to about 2,750 calories today, up from 2,250 forty years ago. This increase has occurred as a result combination of four interlinked factors.

1)      The amount of land used for growing food has increased by about 35%. This increase has, of course, partly come from the destruction of forests, pushing many gigatonnes of carbon into the atmosphere.

2)      Yields per hectare have risen, and are still rising, at  between 1 and 2% per year.

3)      The population has grown sharply

4)      Lastly, diets have changed, implying a need to produce more primary calories in the form of crops for use by animals.

The paper has a very interesting and elegant way of expressing the impact of each of these forces. It estimates the impact on agricultural land area of each factor, showing how the extra cropland was used. Total land area devoted to arable crops rose by nearly 270 million hectares from 840 to about 1,110 million hectares.

We know that global population is likely to increase sharply between now and 2050. The paper assumes that the number rises by about 2bn to around 9bn. (Many people will regard this as improbable, seeing a figure of around 10bn as more likely.) If the rest of world ends up with US style dietary habits, expressed in terms of animal products consumption and overall calorie intake, but also is as good as the US is today at  producing food, then 9bn people of 2050 will need almost double today’s arable land area. If the global patterns are of Western European dietary and agricultural productivity, then the increase is about 70%.

The FAO says that arable land area can be increased by 5% from today’s levels without further loss of forest. The implication is therefore that the world is set on a collision course as rising prosperity meets insufficient land area to meet demand for animal products. The price of food will continue to rise sharply, probably pushing large numbers back into malnutrition. Or the world continues to cut down its forests, increasing carbon losses and also affecting local and regional rainfall patterns. Both routes are terrifying.

As global population increases to about 10 billion in 2050, the world must find ways of increasing the productivity of the limited reserves of usable cropland. Little land is available for conversion from other uses so yields per cropped hectare must grow at close to the rate of population increase. In the past this has proved possible, partly as a result of improved agronomic techniques and hybrid seeds and partly from greater irrigation. Does genetic modification offer a means of continuing the increase as fresh water supplies become stretched? The evidence has been mixed across the world but the Indian experience with cotton is a powerful indication of the issues that can result from GM introduction.

Cotton cultivation in many countries requires huge inputs of pesticide to counter the threat of multiple pests that can reduce yields to virtually nothing. Monsanto’s GM cotton contains one or more genes that produce large concentrations of the natural Bt insecticide in the plant’s leaves. The purpose of the genetic change is to reduce the need for the farmer to spray expensive insecticides which can also severely affect human health.

India has often been touted as strong evidence for the success of Bt cotton, perhaps the country’s most important cash crop. The chart below shows why. Until the turn of the millennium, yields of cotton lint had stagnated at around 300 kilogrammes per hectare of cultivated land. Bt cotton was first officially planted in 2002, though black market seeds were probably in the soil a year earlier. National cotton yields then climbed sharply to levels well over 50% higher. At first sight, the coincident increase in GM plantings and yield increases seems strong evidence for the success of GM.

(Source: Cotton Advisory Board of India for yield figures, SAGE for percentage of GM plantings)

The Indian NGO group, Southern Action on Genetic Engineering (SAGE) points to the possible error in this conclusion. The large part of the yield jump occurred in the first two years after GM introduction. But by that stage only 6% of the cotton planted was Monsanto’s Bt variety. It couldn’t have been the introduction on GM on little more than one twentieth of the land that caused the national increase. Other factors must have played an important role.

The peak year for production per hectare was 2007/08 when yields hit 554 kg per hectare. At this time, 62% of plantings were GM. Since then, the yield has fallen in most years, and is forecast to be 481 kg per hectare in the period to September 2012. SAGE points out that although almost all cotton land in India is now GM, the average yield per hectare will be about the same this year as in 2007/08, when only 6% was planted with GM.

They conclude that GM isn’t helping cotton yields and they are now not alone in their argument. Other NGOs have joined in, railing at the government for encouraging the adaption of Bt cotton a decade ago. But despite the stagnant yields has GM helped in other ways, such as by decreasing the cost of insecticides? The SAGE report says that farmers are now spending 50% more on their agricultural inputs. The seed is more expensive and pesticide use has risen.

So what did cause the sharp rise in yields in the early part of the last decade if it was not the use of GM seeds? One candidate is the increased use of irrigation in Gujarat state. In 2001/02, Gujarat produced 20% of Indian cotton at a yield of 327 kg per hectare, barely above the national average. By 2011/12 projections are for Gujarat yields to be 660 kg per hectare, with the state accounting for 33% of national output. Irrigation seems to have had more impact than GM.

SAGE and other groups have identified several reasons for the apparent failure of GM cotton. First, the insects targeted by the Bt genes have already developed resistance in some parts of India. Other GM crops tagged with Bt genes, such as maize, have begun to see similar problems and so the adaptability of cotton pests should not be a surprise. Second, other pests have moved in to take over. Indian agronomists report increasing problems with pink bollworm, jassids and leaf curl. (As one commentator pointed out ‘in a contest between Monsanto and Darwin, Darwin will always win). Third, GM may have induced a short period of increased yield  but this came at the price of decreasing fertility as soil nutrients were drained by the faster growth. To remedy the deficiency farmers will need to increase the use of artificial fertilisers in the future.

We cannot rule out GM on the basis of a poor history for one crop in one country. But the evidence that GM can sustainably increase agricultural yields is still strikingly inconclusive.

(This is part of Chris Goodall’s forthcoming book, Sustainability: All That Matters, to be published by Hodder later this year).