15th January
Land system change – “The transformation of forests, grasslands, and other natural areas through land use and other human actions.” (1) Land system change is another of the nine planetary boundaries that marks whether life on Earth is sustainable.
Humans have long been transforming the landscapes, from our earliest beginnings in agriculture when other plants including trees, were removed to make way for our own choice of plants. Clearings in forests made space for homes to be built, crops sown and animals corralled. And agriculture is still the biggest driver of land system (or land use) change. Whilst the ploughing up of grassland to sow crops, or the replacing of wildflower meadows with cultivated grass, or building houses on green fields, clearly constitutes land use change, it is in the clearing of forests that the most damage is done. Forests are key parts of the ecosystem that regulate rainfall and flooding, that hold soils intact, that provide shelter from both heat and winds, and which are home to a huge diversity and density of wildlife. When forests are lost, rainfall patterns change, soils dry up and maybe either washed or blown away, rivers dry up and vast quantities of carbon are no longer locked away.
In many regions, deforestation begins with logging – often illegally – and which leads to roadways being created. Land that has been logged gives way to pasture and then cattle ranching, or the growing of crops for animal food or for bio-energy.
The safe limit for land system change is deemed to be when at least 75% of the Earth’s original forest cover remains unviolated. Humanity passed this limit in the 1990s and original forest cover today stands at 60% (2)
Land use changes impacts most of the other planetary boundaries: freshwater levels are negatively impacted by deforestation; switching from trees to crops increases the use of fertilisers and disrupts biogeochemical boundaries; the increased use of pesticides increases the number of novel entities in the Earth’s systems; another side effect of the increased use of pesticides and fertilisers – and the burning of stubble etc – is an increase in airborne particles; increasing livestock farming increases the amount of methane and other greenhouse gases in the atmosphere; whilst at the same time agriculture often leads to a reduction in biodiversity and the diminution of a living spaces for wildlife.
And to compound this current agricultural practices do not produce enough food to ensure a healthy diet for a growing global population (something that could be achieved if different methods of farming were practiced and different diets followed).
Replacing damaging farming practices with more sustainable ones – and switching to more sustainable and healthier diets – is essential. Such transformative action needs to done in ways that are fair and just, benefitting small as well as large farmers, benefitting women as well as men, benefitting, developing as well as developed countries, benefitting poorer as well as wealthier consumers.
The Green Tau 