Planetary boundaries 5 – land

lungsOf all the planetary boundaries, land is the most visible. You can’t see the ozone layer, and we don’t consciously encounter nitrogen in any way, even though you’re breathing it in right now. Land is different. When a new development is proposed at the edge of town, the cry will go up from even the most die-hard anti-green that there isn’t any more space and we need to protect the countryside.

This is of course a land use boundary, not land per se. It’s about how much of the earth’s productive land we use for human activities such as growing food and biofuels, and how much of it we leave to the wild. “Humanity may be reaching a point” says the boundaries report, “where further agricultural land expansion at a global scale may seriously threaten biodiversity and undermine regulatory capacities of the Earth System (by affecting the climate system and the hydrological cycle).”

Clearing land for agriculture is the primary driver of biodiversity loss, as habitats are swept away to create new farms and pasture, but it has other implications too. Forests are carbon sinks and play a critical role in climate change.

The weather is also linked to the ground beneath it, and changes in land use can result in changes to the weather that can become self-reinforcing. This is how desertification occurs, a vicious cycle of drying land and decreasing rainfall. There are tipping points that will trigger that cycle, if deforestation and land degradation reaches a certain point. You could turn the Amazon into the Sahara, eventually, and the experience of the Sahel region shows how hard it is to stop the process once it begins.

So how much of the earth’s land can we use? It’s not easy to say with any accuracy, not least because every region is different. The boundaries report takes a stab at it and says 15% of productive land can be used for human activity. That, in my mind, is one of the report’s weaker moments and looks like a preliminary guess, but it’s a starting point for further analysis.

Assuming they are right, we have a small amount of wriggle room before we start to get into trouble. We currently use 12% of the planet’s ice-free productive land. The 3% we have to play with is not enough expansion room to accommodate the growing population and rising aspirations of the 21st century. We will have to get a whole lot smarter in how we use existing land if we’re to remain within a safe ecological space.

We know most of the things we need to do on that front. Better food systems is one, getting more from the land without increasing pollution in the process. That can be done through sustainable intensified agriculture, or by restoring underused or abandoned agricultural land. I’ve written before about reducing food waste, a chronic problem that sees almost half the world’s food thrown away. Eating less meat would help, but eating habits are cultural and take a long time to change. Biofuels are looking like an increasingly poor use of land, in a world of rising food prices.

Along with using existing land better, the other challenge is to prevent further loss of wild land. That’s easier said than done, because there’s no international land bank and national interests are often in competition with long term global needs. There are some interesting initiatives around forests at the moment though. Maintaining the earth’s forests is critical to preventing runaway climate change, so we need to find a way to value them as forests. Under normal circumstances they have no value until the trees are cut down and the land made available for ranchers or farmers – so that’s exactly what Brazilians or Indonesians do. The biggest initiative is REDD (Reducing Emissions from Deforestation and forest Degradation) which directs international finance to countries that to encourage them to protect their forests. It is one of the few areas of international climate negotiation that appears to be making decent progress.

Another famous plan is Ecuador’s Yasuni National Park. There is oil there, and Ecuador has basically thrown a challenge to the world. They want the money from the oil, but they’d rather gain an income from the forest and leave it intact. They’ve put a price of $3.6 billion on it, which is just half the value of the oil reserves, and it’s probably done more to raise awareness of the importance of forests than anything else in recent years.

Other tracts of forest are being bought up to keep them from being developed too. Norway has unilaterally offered compensation to Indonesia and Brazil in return for logging moratoria. This compensation seems particularly apt when it involves countries that long since shredded their own forests, like Britain. If we weren’t prepared to pay something towards maintaining them, it would be rather hypocritical of us to lament forest loss in other countries when we already chopped all our trees down centuries ago.

One other important way to protect forests is to turn to the forest people that call them home. Forest tribes are often displaced when their lands are turned over to farming, but they are rarely compensated because they have no formal rights. Granting them land rights gives the forests an owner, making them much more likely to be protected. This is a common sense measure that also respects the human rights of minority tribes, so it’s a cause worth backing – see The Rainforest Foundation for more on this approach.

As global demand grows, the temptation to press more and more of the earth’s biocapacity into human service is hard to resist. We are going to have to work together in some new and clever ways.

Land use boundary
Safe limit: 15% of earth’s productive land
Status:  currently safe

If you missed them, here’s are the first few parts of this series: Introduction, Week one: ozone, Week two: nitrogen, Week three: chemical pollution, Week  four: water

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