We frequently read, in both news reports and expert publications, that energy accounts for around 75% of human-induced greenhouse gas (GHG) emissions and food – or, to be more accurate, forestry, land use and agriculture (FLAG) – accounts for the remaining 25%. This seriously understates the importance of FLAG, with serious consequences.
There are two main problems with the claim. The first is that it’s based on a subjective convention: the particular time horizon over which warming effects are measured. As different GHG break down in the atmosphere at different rates – methane within a dozen years, carbon dioxide over centuries – different time horizons yield different outcomes for their relative importance. For no especially compelling reason, the most commonly used timeframe is 100 years. If a shorter timeframe is used, the relative importance of methane increases: for instance, if 20 years is used, the importance of methane roughly triples. Methane is released by both the energy industry and by FLAG in roughly equal measure – so in the extreme that we integrate over a 1-year time horizon, the GHG contributions from energy and FLAG are about the same (prior to consideration of the second issue below).
Of course, if a longer time horizon were to be used, methane and hence agriculture would have a lower measured importance. I don’t know about you, but given the state of the world I’m personally disinclined to have as a working assumption that we’ll make it to 2100, let alone any later.
The second major issue is not subjective at all. Currently about half of the Earth’s entire habitable land surface is devoted to agriculture, predominantly livestock through pasture and grassland, a large proportion of which has been deforested in recent decades. If this process were to be reversed, we could eradicate a large proportion of the net emissions of GHG into the atmosphere. However, the standard calculations of annual emissions ignore this opportunity cost of using the land for livestock: they usually account for net deforestation within the year itself, but do not consider the potential value of the land as a carbon sink. It’s a bit like a royal accountant announcing that the monarch is impecunious, ignoring the capital tied up in his or her palaces, castles and estates.
But what about population – surely there are too many people? It’s not people who take up the land surface per se, it’s our livestock. If, on a global basis, we were to halve our per capita consumption of meat and dairy, and simultaneously the human population were to rise to 10 billion, the total land use by human beings and our animals would still fall, probably by as much as 20-30%.
Perhaps it’s hard for the British in particular to accept that farming is unsustainable, given our centuries-old agricultural practices. How can that be right when we’ve managed perfectly well for hundreds of years? The key consideration is this: if only Britain chooses to use half of its land for animals, the planet can cope, given how tiny Britain is in the global context. When the rest of the world copies the British example – as has happened largely within the last half-century, especially in Asia – the world’s climate is put under strain.
It matters if we are told food “only” accounts for a quarter of our GHG emissions. Not only is the proportion arguably a lot higher, what we eat is within our control. Whilst energy is very important too, it is difficult for us to influence as individuals (with some points of exception, such as home insulation and how much we drive and fly). By contrast, most of us have some choice over what we eat. Meat is not a staple: it is a luxury, increasingly these days both from a financial and environmental standpoint. It doesn’t need to be eradicated, but it does need to be substantially reduced. But while that may be true, we are and will continue to be fed with an alternative narrative, given the power of the farming industry, and our collective reluctance to change.