This December, world leaders will meet in Paris for the United Nations Climate Change Conference, where they will hammer out a comprehensive agreement to reduce carbon emissions and stem global warming. In the run-up to that meeting, governments worldwide should note one critical, but often overlooked, fact: the single biggest driver of environmental degradation and resource stress today is our changing diet – a diet that is not particularly conducive to a healthy life, either.

In recent decades, rising incomes have catalysed a major shift in people's eating habits, with meat, in particular, becoming an increasingly important feature of people's diets. Given that livestock require much more food, land, water, and energy to raise and transport than plants, increased demand for meat depletes natural resources, places pressure on food-production systems, damages ecosystems, and fuels climate change.

Meat production is about ten times more water-intensive than plant-based calories and proteins, with one kilogram of beef, for example, requiring 15,415 liters of water. It is also an inefficient way of generating food; up to 30 crop calories are needed to produce one meat calorie.

At any given time, the global livestock population amounts to more than 150 billion, compared to just 7.2 billion humans – meaning that livestock have a larger direct ecological footprint than we do. Livestock production causes almost 14.5 percent of global greenhouse-gas emissions and contributes significantly to water pollution.

Moreover, livestock production consumes one-third of the total water resources used in agriculture (which accounts for 71 percent of the world's water consumption), as well as more than 40 percent of the global output of wheat, rye, oats, and corn. And livestock production uses 30 percent of the earth's land surface that once was home to wildlife, thereby playing a critical role in biodiversity loss and species extinction.

It took more than a century for the European diet to reach the point at which meat is consumed at every meal, including breakfast. But, in large parts of Asia, a similar shift has occurred in just one generation. Meaty diets have created a global obesity problem, including, of all places, in China, whose expanding international clout is accompanied by expanding waistlines at home.

Americans consume the most meat per capita, after Luxembourgers. Given the size of the US population, this is already a problem. If the rest of the world caught up to the United States – where meat consumption averages 125.4 kilograms per person annually, compared with a measly 3.2 kilograms in India – the environmental consequences would be catastrophic. 

Already, the signs are worrying. The demand for meat is projected to increase by 50 percent from 2013 to 2025, with overall consumption still rising in the West and soaring in the developing world, especially Asia.

In order to meet this demand, meat producers have had to adopt an extremely problematic approach to raising livestock. In order to ensure that their animals gain weight rapidly, meat producers feed them grain, rather than the grass that they would naturally consume – an approach that is a major source of pressure on grain production, natural resources, and the environment.

Making matters worse, the livestock are injected with large amounts of hormones and antibiotics. In the US, 80 percent of all antibiotics sold are administered prophylactically to livestock. Yet this has been inadequate to stem the spread of disease; in fact, with many of the new and emerging infectious diseases affecting humans originating in animals, veterinarians, microbiologists, and epidemiologists have been trying to understand the "ecology of disease" (how nature, and humanity's impact on it, spreads disease).

Though the environmental and health costs of our changing diets have been widely documented, the message has gone largely unheard. With the world facing a serious water crisis, rapidly increasing global temperatures, staggering population growth, and growing health problems like coronary disease, this must change – and fast.

For starters, to ease some of the resource pressure, livestock producers should switch to water-saving technologies, including drip irrigation. At the same time, governments and civil-society groups should promote healthier diets that rely more on plant-based proteins and calories.

According to recent research, if the world stopped producing crops for animal feed or diverting them to biofuels, it could not only end global hunger, but also feed four billion extra people – more than the number of projected arrivals before the global population stabilizes. Meat consumption actually leads to more greenhouse-gas emissions annually than the use of cars does.

This is not to say that everyone must become a vegetarian. But even a partial shift in meat-consumption habits – with consumers choosing options like chicken and seafood, instead of beef – could have a far-reaching impact. Indeed, beef production requires, on average, 28 times more land and 11 times more water than the other livestock categories, while producing five times more greenhouse-gas emissions and six times more reactive nitrogen.

Adopting a balanced, largely plant-based diet, with minimal consumption of red and processed meat, would help conserve natural resources, contribute to the fight against human-induced global warming, and reduce people's risk of diet-related chronic diseases and even cancer mortality. Just as governments have used laws, regulations, and other tools with great success to discourage smoking, so must they encourage citizens to eat a balanced diet – for the sake of their health and that of our planet.

The writer is Professor of Strategic Studies at the New Delhi-based Center for Policy Research and Fellow at the Robert Bosch Academy in Berlin, is the author of nine books, including Asian Juggernaut; Water: Asia's New Battleground; and Water, Peace, and War: Confronting the Global Water Crisis.

Copyright: Project Syndicate, 2015.
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