Emissions from global food system imperil Paris climate goals, study finds

The global food system’s greenhouse gas emissions will add nearly 1C to Earth’s surface temperatures by 2100 on current trends, scientists warned on 6 March. This would obliterate the Paris Agreement climate goals.

But a major overhaul of the sector – from production to distribution to consumption – could reduce those emissions. A transformation of the sector could cut emissions by more than half even as the global human population increases, the  scientists reported in Nature Climate Change.

Food system emissions

The Earth’s surface has warmed 1.2C since the late 1800s. The 2015 Paris Agreement set a core goal of trying to limit warming to 1.5C. They also seek to cap it at “well under” 2C.

Science has shown the 1.5C limit to be a much safer threshold to avoid more devastating climate impacts, including coastal flooding, heatwaves and drought, and possibly irreversible climate tipping points. These are thresholds that could trigger large-scale changes in the Earth system, such as the collapse of certain vast ice sheets.

As Carbon Brief has reported, research indicates that, at warming above 1.5C, there is a “significant likelihood” of the world crossing multiple tipping points.

According to some estimates, the global food system accounts for about 15% of current warming levels. Nonetheless, only a third of national emissions reductions plans under the Paris pact include any measure to cut carbon pollution from agriculture or animal-based farming. The study’s lead author Catherine Ivanovich, a doctoral student at Columbia University in New York, told Agence France-Presse:

Mitigating emissions from the food sector is essential to working toward a secure climate future

Food emissions in the future

To make their own estimates of how much the food system adds to global warming – now and in the future – Ivanovich and her colleagues looked separately at the three main greenhouse gases. These gases vary in potency and staying power in the atmosphere.

Once emitted, carbon dioxide can remain in the atmosphere for centuries. Methane only lingers for about a decade but, on that timescale, is almost 100 times more efficient in retaining the Sun’s heat.

CO2 from machinery and transport are significant contributors to greenhouse gas emissions. Nitrous oxide from excess use of chemical fertilisers is similarly harmful. But the researchers calculated that around 80% of:

future warming from food consumption will be from meat, rice and dairy products.

These are “high-methane food groups”, they highlighted.

Without a sharp change in production and diet, the study concluded, global food consumption will boost Earth’s average surface temperature 0.7C and 0.9C by century’s end. The authors emphasised that:

This additional warming alone is enough to surpass the 1.5C global warming target and approach the 2C threshold

The study based its estimates on the continuation of “current dietary patterns and agricultural production practices”. As the study highlighted, this means that if consumption levels of animal-based foods increase, as projected, the situation could be much worse.

Dietary change needed

Methane, the study showed, is clearly the key to curbing food-related carbon pollution. Ivanovich said:

The majority of future warming from the food sector comes from the emissions of methane

“Because it is a short-lived pollutant, immediate reductions in its emissions can result in climate benefits in the near future.”

The study found that improving production methods for meat, dairy, and rice, and slashing food waste would help to cut these emissions. The same can be said of using renewables rather than fossil fuels for power.

Meanwhile, people adopting a diet optimal for human health could curb the emissions by 0.2C. This is around 20% of the anticipated warming, according to the analysis. The researchers used Harvard medical school’s recommendations as the measure of a healthy diet. It advises only a single serving of red meat weekly and “limited consumption” of other animal-based foods, namely fish, birds, and eggs. This means a substantial drop in consumption of animal-based foods is necessary in richer countries. Conversely, some poorer countries could increase consumption.

To date, however, trend lines for many of these measures are stagnant. In the case of meat consumption, they’re moving in the wrong direction.

Additional reporting by Agence France-Presse

Featured image via Vaarok / Wikimedia, cropped to 770×403, licensed under CC BY 2.5