Food’s role in climate change has emerged as one of the defining challenges of our time. The journey of a steak, fruit or salad from the vast expanses of agricultural lands to the plates on our tables leaves a significant footprint on the environment.

At the heart of this challenge is the prodigious use of fertilizers and a growing global population’s increasing demand for meat.

As earth, climate and atmospheric scientists, we track global greenhouse gas emissions and just published the most comprehensive assessment yet of a powerful greenhouse gas from food production: nitrous oxide, or N2O.

After carbon dioxide and methane, N2O is the most consequential greenhouse gas humans are releasing into the atmosphere. While there is less N2O than carbon dioxide in the atmosphere, it is 300 times more powerful at warming the planet, and it remains in the atmosphere, holding in heat, for over a century. Today, atmospheric N2O levels are about 25% higher than before the Industrial Revolution, and they’re still rising at an accelerating rate.

However, the human population and its demand for food have grown rapidly, throwing that natural equilibrium out of whack.

We found that human activities alone have increased N2O emissions by 40% over the past four decades, with agriculture contributing approximately 74% to the total anthropogenic N2O emissions.

The biggest human sources of N2O are agriculture, industry and the burning of forests or agriculture waste.

Emerging economies, such as China and India, have had strong increasing N2O trends over the past four decades as they boosted agricultural productivity to meet their growing populations’ food demand.

 

China is the largest producer and user of chemical fertilizers. Its Action Plan for Zero Growth in Fertilizer Use by 2020, issued in 2015, has helped cut those N2O emissions. However, its industrial N2O emissions have continued to rise.

In Brazil and Indonesia, cutting down and burning forests to make room for crops and livestock, coupled with increasingly intensive farming practices, has exacerbated nitrogen losses from natural sources and amplified greenhouse gas emissions.

Africa has opportunities to increase food production without increasing nitrogen fertilization. However, Northern African countries more than tripled their emissions growth in the past two decades, primarily due to a substantial growth in the livestock population in Africa.

A few regions, however, have been able to curtail some of their N2O emissions with more sustainable practices.

 

The European Union, Japan and South Korea have all successfully reduced anthropogenic N2O emissions over the past 40 years, although they remain major emitters on a global scale; reductions have largely come from the chemical industry in the 1990s. Their nitrogen use in agriculture has also become more efficient; however, they still have work to do. Their emissions from direct fertilizer and manure application have declined only slightly and have recently leveled out.

In the U.S., agricultural emissions continue to creep up, while industrial emissions have declined slightly, leaving overall emissions rather flat.

How to reduce N2O emissions

Addressing the challenge of reducing N2O emissions requires a combination of policy interventions, technological innovation and individual actions. For example:

• Policies can encourage farmers to adopt nitrogen-efficient practices, optimize fertilizer use and reduce N2O emissions and other forms of nitrogen pollution through a variety of incentive programs.
• Precision agriculture techniques, including the use of remote sensing and satellite GPS-guided equipment, can help farmers vary the rate of fertilizer applied to optimize nutrient management and minimize nitrogen losses, thereby reducing N2O emissions.
• The development and adoption of nitrogen-efficient fertilizers, such as controlled-release formulations and nitrification inhibitors, also offer promising ways to reduce nitrogen runoff and curb N2O emissions from agricultural soils.

• Similarly, innovations in livestock management, such as dietary supplements and improved waste management practices, can reduce the amount of N2O from cattle.
• Industries, particularly production of nylon and fertilizers, can install existing, affordable technologies to abate nearly all of their N2O emissions. That’s an easy win for implementation and the climate. Most of the world has already done so, leaving China and the U.S. responsible for most of the remaining industrial emissions of N2O.
• Consumers can also make plant-based foods a larger fraction of their diets. You don’t need to become vegan unless you want to, but reducing the frequency and portion sizes of meat and dairy consumption can be healthy for both you and the environment. Eco-friendly practices like composting food wastes and reducing fertilizer use on lawns also help.

Overall, a holistic approach combining policy, technology and individual actions is needed to address N2O emissions and combat climate change. With governments, industries and citizens all working toward a sustainable future, these strategies can help ensure food security and environmental sustainability for future generations.

Hanqin Tian is a director and institute professor at the Center for Earth System Science and Global Sustainability, Schiller Institute for Integrated Science and Society at Boston College.

Eric Davidson is a professor at the University of Maryland, Baltimore.

Pep Canadell is a chief research scientist at CSIRO Environment and an executive director at the Global Carbon Project, CSIRO.

Rona Louise Thompson is a senior scientist at the Norwegian Institute for Air Research.

This article is republished from The Conversation under a Creative Commons license. Read the original article.