Over 58% of our planet’s land and 41% of its oceans are already under moderate to intense human pressure. This means that most newly protected areas will effectively be works in progress, with restoration projects to help species recover, improve habitat quality and make ecosystems healthier.

Another 40% of land and 10% of oceans have experienced relatively low impacts from human activities. Terrestrial ecosystems with the lowest human footprints include tundra, boreal forests and deserts. At the other extreme, tropical, subtropical and temperate forests are at the highest risk.

In the oceans, areas with the lowest human pressures are near the poles or in polar regions. Coral ecosystems, which are home to 25% of all marine life, are under the most pressure.

It isn’t always possible to protect large areas. Some scientists argue that small areas can still successfully protect species, but others disagree. In our view, what ultimately matters is how multiple protected areas are connected and how close they are to each other.

Connections can develop naturally, like the flyways that migrating birds use to travel between continents. Or they can be structures built by humans, such as wildlife bridges over highways. Connecting protected areas is important because it promotes genetic diversity and makes it possible for species to move in response to climate change and other threats.

Given all these factors, selecting protected areas can get complicated. Based on our research, we think that a holistic approach can make 30x30 feasible and effective. It has three parts.

First, protected areas should meet both conservation needs and human needs. Second, in creating newly protected areas, researchers and managers should consider how they will interact with adjacent areas. Third, researchers and officials should assess how newly protected areas will interact with areas far away – including in other countries.

This approach is guided by the metacoupling framework, which is an integrated way to study and manage human-nature interactions within and between different places. It recognizes that human and natural systems in a given place can be affected for better or worse by people, policies and markets both nearby and far away.

At Wolong Nature Reserve in southwestern China, one of us, Jack Liu, has worked with Chinese collaborators to understand and manage human-nature interactions in ways that support the recovery of a global wildlife icon – giant pandas. Wolong, which is now part of China’s Giant Panda National Park, was one of the first and largest panda reserves in China, and also houses numerous other rare animals and plants. It is also home to almost 6,000 people.

Forest is an important part of panda habitat, but over time the human population in Wolong grew and needed more resources, such as wood for cooking and heating or to make goods for visiting tourists. In a 2001 study, our team showed that panda habitat in Wolong declined faster after the reserve was established in 1975 than it had before that time. Increasing demand for wood was degrading and fragmenting the forest and negatively affected panda population numbers.

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