The other inconvenient truth: the crisis in global land use

As the international community focuses on climate change as the great challenge of our era, it is ignoring another looming problem - the global crisis in land use.

It’s taken a long time, but the issue of global climate change is finally getting the attention it deserves. While enormous technical, policy, and economic issues remain to be solved, there is now widespread acceptance of the need to confront the twin challenges of energy security and climate change. Collectively, we are beginning to acknowledge that our long addiction to fossil fuels - which has been harming our national security, our economy and our environment for decades - must end. The question today is no longer why, but how. The die is cast, and our relationship to energy will never be the same.

Unfortunately, this positive shift in the national zeitgeist has had an unintended downside. In the rush to portray the perils of climate change, many other serious issues have been largely ignored. Climate change has become the poster child of environmental crises, complete with its own celebrities and campaigners. But is it so serious that we can afford to overlook the rise of infectious disease, the collapse of fisheries, the ongoing loss of forests and biodiversity, and the depletion of global water supplies?

Although I’m a climate scientist by training, I worry about this collective fixation on global warming as the mother of all environmental problems. Learning from the research my colleagues and I have done over the past decade, I fear we are neglecting another, equally inconvenient truth: that we now face a global crisis in land use and agriculture that could undermine the health, security, and sustainability of our civilisation.

Our use of land, particularly for agriculture, is absolutely essential to the success of the human race. We depend on agriculture to supply us with food, feed, fibre, and, increasingly, biofuels. Without a highly efficient, productive, and resilient agricultural system, our society would collapse almost overnight.

But we are demanding more and more from our global agricultural systems, pushing them to their very limits. Continued population growth (adding more than 70 million people to the world every year), changing dietary preferences (including more meat and dairy consumption), rising energy prices, and increasing needs for bioenergy sources are putting tremendous pressure on the world’s resources. And, if we want any hope of keeping up with these demands, we’ll need to double, perhaps triple, the agricultural production of the planet in the next 30 to 40 years.

Meeting these huge new agricultural demands will be one of the greatest challenges of the 21st century. At present, it is completely unclear how (and if) we can do it.

If this wasn’t enough, we must also address the massive environmental impacts of our current agricultural practices, which new evidence indicates rival the impacts of climate change. Consider the following:

Ecosystem degradation. Already, we have cleared or converted more than 35 per cent of the earth’s ice-free land surface for agriculture, whether for croplands, pastures or rangelands. In fact, the area used for agriculture is nearly 60 times larger than the area of all of the world’s cities and suburbs. Since the last ice age, nothing has been more disruptive to the planet’s ecosystems than agriculture. What will happen to our remaining ecosystems, including tropical rainforests, if we need to double or triple world agricultural production, while simultaneously coping with climate change?

Freshwater decline. Across the globe, we already use a staggering 4,000 cubic kilometres of water per year, withdrawn from our streams, rivers, lakes and aquifers. Of this, 70 per cent is used for irrigation, the single biggest use of water, by far, on the globe. As a result, many large rivers have greatly reduced flows and some routinely dry up. Just look at the Aral Sea, now turned to desert, or the mighty Colorado River, which no longer sends any water to the ocean, for living proof. And the extraction of water from deep groundwater reserves is almost universally unsustainable, and has resulted in rapidly declining water tables in many regions of the world.

Future water demands from increasing population and agricultural consumption will likely climb between 4,500 and 6,200 cubic kilometres per year, hugely compounding the impacts of climate change, especially in arid regions.

Widespread pollution. Agriculture, particularly the use of industrial fertilisers and other chemicals, has fundamentally upset the chemistry of the entire planet. Already, the use of fertilisers has more than doubled the flows of nitrogen and phosphorus compounds in the environment, resulting in widespread water pollution and the massive degradation of lakes and rivers. Excess nutrient pollution is now so widespread, it is even contributing to the disruption of coastal oceans and fishing grounds by creating hypoxic “dead zones”, including one in the Gulf of Mexico.