Our impact is huge
When my television goes into screensaver mode, the Apple gadget I use to watch Netflix displays an endless loop of videos of Earth from above. What always strikes me is how extensive is humanity’s mark on the planet. Even in the remotest deserts and icy wastelands, you’ll still see the angular track of roads, electricity lines and oil and gas pipelines.
A newly published international research project has calculated with unprecedented precision the extent of that change over time. Researchers combined information from remote sensing satellites with historic land use assessments and found that between 1960 and 2019, we have changed the land use of 17 per cent of the world’s land surface area.
We’ve altered 43 million square kilometres of land, equivalent to 32 per cent of Earth’s land surface. That’s like changing an area of land twice the size of Germany every year since 1960. The big changes won’t come as a surprise. Urban areas have grown. Forested areas have shrunk by 0.8 million square kilometres, cropland has expanded by
1 million square kilometres and pastures have expanded by 0.9 million square kilometres.
HILDA+, the Historical Land Dynamics Assessment model the researchers have developed, tells the story of the past 60 years of life on Earth. From the 1960s, the green revolution saw a steady expansion of cropland in places like Africa, Southeast Asia and South America. That helped save hundreds of millions of people from the risk of starvation. By the 1990s, globalisation was changing the landscape again, as the wealthy Global North effectively offshored their land requirements. The poor Global South increasingly switched to commodity crops such as soybean, sugarcane, palm oil and cocoa to meet demand in richer countries, cutting down forests to plant more crops.
The biggest land use changes locally over the past 30 years or so have involved a shift away from sheep and beef farming to dairying and forestry, with a smaller increase in the size of our cities and towns, seeing them encroach on some of our most productive soil.
HILDA+ also tells the story of spiking oil prices, which led to more land being converted to crops suitable for biofuel, and the economic crisis of 2007-2009, which crimped trade and slowed the boom in commodity crops.
The model reveals crop abandonment in some countries due to persistent drought and the recent flurry of forest planting in northern countries seeking to lower carbon emissions.
This fascinating global snapshot of land use can help us track the impacts of climate change and biodiversity loss and create more accurate carbon budgets.
HILDA+ reminds us that the land use decisions we make in the coming decades will be crucial to our future.
The land use decisions we make in the coming decades will be crucial to our future.