It has been clear for sometime that the fight to lower greenhouse gas (GHG) emissions, and mitigate climate-change impact, rests on a drastic rethink of global land use. A large part of land use is tied to human diet, from pastures for grazing of meat animals to agriculture. A new report by the Intergovernmental Panel on Climate Change (IPCC) on climate and land says a plants-based diet will be kinder on the planet than a meat-based one. It recommends that governments, especially those of rich nations, where meat consumption is high, work on reducing this.
Land use and management, including agriculture and deforestation, contribute almost a quarter of the GHG emissions. Unless land is managed more sustainably, keeping global warming under 1.5oC above pre-industrial levels, is impossible—countries, thus, have included land-use, land-use change and forestry in their Intended Nationally Determined Contributions announced as part of the 2015 Paris Agreement. While deforestation for pastures to graze cattle, like in Brazil and Colombia, is particularly emission-intensive, cattle, too, produce large amounts of methane, a potent GHG. Besides, the emission foot-print of manufacturing animal-feed, water- and electricity-use in raising and slaughtering of meat animals, and processing/packaging of meat is significant. The IPCC report, thus, says that balanced diets that are plant-based and feature sustainably-produced animal-sourced food “present major opportunities for adaptation and mitigation”. Indeed, by 2050, the report says, dietary changes could free up millions of square kilometres of land and reduce global carbon emissions by upto 8 billion tonnes annually (relative to business-as-usual). Though, perhaps with the politics and socio-cultural sensibilities associated with dietary habits in mind, authors of the report have refrained from telling people what to eat. Given land use across the world contributes $75-85 trillion to the global economy annually (2011, based on the value of the dollar in 2007)—this is many times the world’s combined GDP—influencing land use in favour of more sustainable practices is also a fraught economic question, with the livelihoods of hundreds of millions of people tied to it.
The risks a shifting to a largely plant-based diet also must be considered. Rice-farming, for instance, accounts for 24% of agricultural methane emissions. In a country like India, where rice is a staple and one of the largest agricultural exports, pushing a plant-based diet could result in more demand for unsustainably produced rice. Also, nitrous oxide emissions—a potent heat-trapper, with one tonne being equivalent to 265 tonnes of CO2 over 100 years—from agriculture have almost doubled since the 1960s, given fertiliser application has increased nine-fold globally. Besides, research by the Carnegie Mellon University shows that, without reducing caloric intake significantly, simply changing the diet to include the US department of agriculture (USDA) advised food mix, or reducing caloric intake while sticking to the USDA food mix recommended for a healthy weight, will increase GHG emissions and energy/water use .
The window to act on sustainable land use is narrowing fast. Human use already affects 60-85% of forests and 70-90% of other natural ecosystems. Land—the forests on it as well as the soil—plays a key role as a carbon sink. But, with manifest climate change effects, desertification and degradation of land is becoming an ever-growing threat, and humans are responding with even more unsustainable use—fertiliser use, excessive groundwater extraction, stripping down of rainforests, etc, are key examples. The IPCC report, therefore, calls for stepping up efforts to keep the land productive while enhancing its carbon-absorbing capacity—a carefully calibrated, primarily plant-based diet could be one way to do this.
