Helen Harwatt

The world’s use of nitrogen fertilisers for food production could threaten efforts to keep global warming below 2C above pre-industrial levels. That is according to the Global Carbon Project’s first comprehensive assessment of how nitrous oxide (N2O) emissions are contributing to climate change. Published in Nature, the results show that human-caused N2O emissions have increased by 30% over the past four decades – with the use of nitrogen fertilisers in agriculture playing a major role in the uptick. A growing demand for meat and dairy products has also contributed to the surge. This is because livestock manure causes N2O emissions and nitrogen fertilisers are often used in the production of animal feed, the scientists say...The results “further highlight the need to raise agriculture up the climate change agenda”, says Dr. Helen Harwatt, a senior research fellow at Chatham House and food and climate policy fellow at Harvard Law School, who was also not involved in the study. She tells Carbon Brief: “Measures to reduce N2O emissions from the agriculture sector align with the broader requirements of food system transformation to meet key planetary health goals. [Such measures include] a shift to plant-based eating patterns to reduce the disproportionate burden of animal agriculture on all three major greenhouse gases – N2O, CO2 and methane.”

To mark a week-long series of articles looking at food and climate change, Carbon Brief hosted its latest webinar on Thursday...The topic for discussion was: “Do we need to stop eating meat and dairy to tackle climate change?” It comes after an interactive Carbon Brief explainer exploring the climate impact of meat and dairy, and an in-depth Q&A examining dietary trends around the world. Other articles in the series include guest posts on emissions from coronavirus-related food waste and future diets in low- and middle-income countries, as well as a piececompiling expert views on how diets will need to change to achieve international climate targets...The webinar featured four panelists, whose collective expertise covers a range of topics relating to food and climate change...Dr. Helen Harwatt is senior research fellow at Chatham House and food and climate policy fellow at Harvard Law School. At the end of last year she wrote a letter to Lancet Planetary Health calling for countries to set timeframes for “peak livestock” in order to meet the Paris Agreement targets. She talked about the carbon sequestration benefits that can come from restoring native vegetation on agricultural land, following dietary shifts away from animal products. This was based on her recent study published in Nature Sustainability.

Switching from eating ‘land-hungry’ meat and dairy produce to foodstuffs like beans, lentils and nuts could remove 16 years’ worth of CO2 emissions by 2050. Researchers from the US calculated that broad uptake of such plant-based protein alternatives could free up land to support more ecosystems that absorb carbon. At present, around 83 per cent of the world’s agricultural land is given over to meat and dairy-based production — much of which only produce low yields. Reducing this figure, the team said, is a better way to combat climate change than waiting for ‘unproven’ large-scale technologies like atmospheric CO2 extractors. "The greatest potential for forest regrowth, and the climate benefits it entails, exists in high- and upper-middle income countries," said paper author and environmental scientist Matthew Hayek of New York University. These, he added, are "places where scaling back on land-hungry meat and dairy would have relatively minor impacts on food security." In the study, Professor Hayek and colleagues mapped out the areas of the globe where land use for animal-sourced food production has squeezed out native vegetation, such as forests. This allowed the team to determine where a shift in our diets to more plant-based foodstuffs could allow natural ecosystems to be restored — helping to offset global carbon dioxide emissions in the process... "We now know that intact, functioning ecosystems and appropriate wildlife habitat ranges help reduce the risk of pandemics," added environmental social scientist and Helen Harwatt of the Harvard Law School, a co-author on the study. "When coupled with reduced livestock populations, restoration reduces disease transmission from wildlife to pigs, chickens, and cows, and ultimately to humans." The full findings of the study were published in the journal Nature Sustainability.

Livestock production needs to reach its peak within the next decade in order to tackle the climate emergency, scientists have warned. They are calling for governments in all but the poorest countries to set a date for “peak meat” because animal agriculture is a significant and fast-growing source of global greenhouse gas emissions. Cattle and sheep emit large amounts of methane while forests are destroyed to create pasture and grow the grains that are fed to intensively reared animals... “Countries should be looking for peak livestock within the next 10 years,” said Helen Harwatt, a fellow at Harvard Law School in the US and lead author of the letter. “This is because we need steep and rapid reductions in greenhouse gas emissions, as we are reaching dangerous temperature tipping points.”