* Any views expressed in this opinion piece are those of the author and not of Thomson Reuters Foundation.

As population rises, appetites change and climate change takes hold, we need a new way to feed ourselves

With the world’s population predicted to reach 9 billion by 2050, we collectively face a dual challenge: ensuring that everyone will have access to affordable, nutritious food without decimating the earth’s natural resources in the process.

This is easier said than done. Our current food system is dysfunctional both in its impact on people and the planet. Unless we change course, we will fail to meet this challenge.

Today, millions do not have enough to eat and billions lack the right nutrients to be healthy. The UN’s food organisations – the Food and Agriculture Organization (FAO), the World Food Programme (WFP) and the World Health Organization (WHO) – have just published their annual 2014 report on global food insecurity. Their report highlights that despite some evidence of progress 805 million people - or 1 in 9 people – still suffer from hunger.

Poor diets stunt the growth of 162 million children every year, 97 percent of them in the developing world, trapping communities in a cycle of poverty and ill health. The consequences for those affected can be devastating. Malnourished children tend to start school later, have poorer levels of concentration and lower scores in cognitive ability tests. Many carry these burdens through into later life.

According to the WHO, a staggering 2 billion people are affected by iron deficiency which contributes to anaemia. More than 250 million children suffer from Vitamin A deficiency which is a major public health challenge in more than half the countries on the planet, with half a million children going blind each year. Half of these children die within 12 months.

Meanwhile, 1.3 billion of us are classified as overweight or obese, fuelled by a food system that is damaging not just our bodies but the environment too. If trends towards Western diets continue, the impact of food production alone will reach, if not exceed, the global targets for total greenhouse gases.

FOOD WASTE

Our current agricultural production system is inefficient. We continue to destroy tropical forests for agricultural expansion and this contributes 12 percent to the total warming of the planet today. And much of the food we produce, we waste. Figures from the Institute of Mechanical Engineers show as much as 2 billion tonnes of food – 50 percent of all we produce – never makes it onto a plate.

What is a crisis for many now could become a catastrophe for more in the future because of the effects of climate change. Climate change is already making people hungry - disrupting crop yields, pushing prices up and increasing food insecurity for large numbers of the world's population.

And it is not just food but nutrients that are becoming scarcer as the climate changes. A study led by the Harvard School of Public Health found that rising levels of CO 2 are stripping staple foods of vital nutrients, rendering crops such as wheat, rice and soya less nutritious for millions of people in developing countries. If these climate and socio-economic trends continue, the number of under-nourished children in Africa alone is expected to rise ten-fold by 2050.

It is against this backdrop that world leaders have come together at the Climate Summit in New York to secure buy-in for a global climate deal next year. In the same week, in the same city, governments meeting at the U.N. General Assembly are reviewing proposals for the post-2015 development goals that aim to eliminate poverty and hunger for good.

AVOIDING A DOWNWARD SPIRAL

If we fail to act, we risk a downward spiral in which poverty and climate impacts reinforce each other. It is the poorest communities that will suffer the worst effects of climate change, including increased hunger and malnutrition as crop production and livelihoods are threatened. And poverty is a driver of climate change, as desperate communities resort to unsustainable use of resources to meet current needs.

But there is an alternative path. In the face of climate change, our basic food systems have to be reimagined so that the world is producing nutritious food in a more sustainable way that increases livelihoods.

This means supporting the world’s smallholder farmers so that they are able to grow, sell and eat more nutritious foods; it means converting degraded lands into productive farms; fortifying staple foods with essential nutrients like iron and zinc; and developing alternative sources of food.

It also means scaling up existing sustainable interventions that we know already work well like breastfeeding for infants. All can play a role in reducing malnutrition and reducing the carbon footprint of the food we eat. All will rely on ambition, innovation and leadership.

It’s only by bringing together business, civil society and governments that we will find solutions that can be scaled up for maximum impact. Countries, companies and NGOs can create a better future, leading by example and catalysing action in their peer groups or industries. But we need ambitious targets and a common vision. We cannot afford to talk about hunger without addressing climate change, food production without sustainability or growth without good nutrition.

As climate and development goals are debated this week and in the months ahead, it should be with these links in mind. A healthier, more sustainable future is possible. But, the sustainability, food and health nexus must be dealt with together if we are going to fix the global food system.

Paul Polman is CEO of Unilever, a member of the Scaling Up Nutrition (SUN) Movement lead group and chairman of the World Business Council for Sustainable Development. Marc Van Ameringen is executive director of the Global Alliance for Improved Nutrition. He is the recipient of the 2014 World Food Program Hunger Hero Award.