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Urban Land Conversions Threaten Biodiversity

Apr 07, 2022

A recent study published in PNAS (The Proceedings of the National Academy of Science) titled, “Biodiversity impacts and conservation implications of urban land expansion projected to 2050,” elucidates the ongoing impacts of human population growth on biodiversity.

The opening paragraph lays out the problem:

Over the next 30 years, the global urban population is projected to increase by 2.5 billion people, making urbanization one of the defining transformations of the 21st century. Urban land will need to expand substantially in order to accommodate these new urban residents, a process that often occurs at the expense of natural ecosystems. At a time when global biodiversity is seriously threatened, this represents a challenge for sustainable urban development.

Interestingly, the United Nations Population Division projects that total world population will increase by 1.8 billion between 2022 and 2052. This connotes that urbanization is on track to exceed the sum of humanity’s natural population growth over the next 3 decades. In other words, “The Great Urbanization,” continues apace.

Proponents of urbanization tend to feel that human society achieves certain economic efficiencies as people live closer and closer together. “The clustering of people generates higher productivity and higher wages. A mix of specialization and diversity generates a fertile environment for innovation in ideas, technologies and processes.”

But, as the authors of the PNAS study point out, urban land conversions are a prominent driver of habitat and biodiversity loss. Therefore, the scale of humanity’s current urbanization is a monumental threat to biodiversity.

Tragically, the expected urban land conversions indicate that up to 290,000 km2 of natural habitat is likely to have been lost between 2000 and 2030. For reference, that is considerably larger than the whole United Kingdom (242,495 km2). Most worryingly, this includes a tripling of urban land near protected areas.

In a related PNAS commentary, titled “Sprawling cities are rapidly encroaching on Earth’s biodiversity,” authors William F. Laurance and Jayden Engerta note:

“Two broad trends underlay the global proliferation of cities. The first is intrinsic population growth. Earth’s populace has risen fivefold since the beginning of the nineteenth century and is now nearly 8 billion people. According to the median projection of the United Nations Population Division, the global population will continue to grow apace this century, reaching 9.7 billion by 2050 and 11.2 billion by 2100, before roughly stabilizing thereafter. These increases largely result from rising human numbers in developing nations, which are primarily located in tropical and subtropical regions that are the epicenters of global biodiversity.”

Of course, we should also remember that devastating harms to biodiversity have already occurred in Europe, North America, and elsewhere all around the world.

In addition to developing strategies for minimizing the impacts of urban land, and strengthening global biodiversity protection agreements, ongoing work to create the conditions for global population growth to slow down and stop is a key contributor to alleviating humanity’s grievous pressure on biodiversity.