In the year 2000, there were more than 650,000 square kilometers of urbanized land on the planet. Compared to the roughly 149 million square kilometers of land area on earth, that's not a whole lot. But with populations growing, that small portion of urbanized land is expected to get bigger. By 2030, it's highly likely that urbanized land will cover nearly twice what it did in 2000, rising to about 1.2 million square kilometers.
How this growth happens will not be evenly spread across the planet. According to new research published in the journal PNAS, the global growth of urban land will have detrimental impacts on biodiversity around the world, especially in certain sensitive areas. The research also includes projections on where urban land is expected to grow and by how much.
Using more than 1,000 models of urban growth, the researchers have identified places where urban growth is almost certain to occur – areas with a probability of urban growth between 75 percent and 100 percent. They've also modeled how much urban growth can be expected. The chart below, created with this data, shows the regions where urban growth is expected to occur the most between now and 2030.
China is the leader here, with an expected increase of more than 219,000 square kilometers of urban land by 2030. The mid-latitudinal region of Africa is also expected to see big changes, adding more than 180,000 square kilometers by then. South America's not far behind, with an expected addition of 134,000 square kilometers. If all this growth does occur, there will be a 185 percent overall increase in the global urban footprint by 2030.
Of course, some areas will see significantly more growth than others. The chart below shows which regions will experience high rates of growth compared to their urban land coverage in 2000.
China, which had been the leader in the first chart, suddenly seems average, and South America drops even lower. Indeed, the most urban growth in terms of rapid rural-to-urban land conversion will occur in the mid-latitudinal regions of Africa – that band of area running right across the middle of the continent. The northern shores of Lake Victoria are expected to become a massive new urban mega agglomeration, and UN predictions suggest that cities in Nigeria could grow by upwards of 200 million people by 2050. Southern Asia is also a hotspot for rapid rural-to-urban land conversion, especially in countries like India, Pakistan, and Sri Lanka.
The impact on biodiversity will be especially significant, according to the researchers. If these highly probable land shifts do occur, global biodiversity hotspots taken over by urban land will increase 200 percent between 2000 and 2030. The environmental concern is huge. But also concerning should be the vast amounts of rural land in some places that are on the verge of turning – almost overnight – into the urban areas of the very near future.
Top image: Crowds fill into a main street in Lagos, Nigeria. Credit: Akintunde Akinleye / Reuters