SYDNEY—Must conservation and economic development always be locked in combat, with no hope for one unless the other is suffering?

At the World Parks Congress, a once-a-decade global forum on protected areas that drew more than 6,000 delegates from 170 countries to Australia this week, influential voices argued again and again that the typically opposing forces must be linked in tandem.

Forty percent of the global economy is based on natural resources, so the need to maintain natural capital is a no-brainer, various speakers said.

The theme was introduced by Achim Steiner, the executive director of the United Nations Environment Program, who spoke about the need to move past the old paradigm in remarks at the opening of the eight-day congress.

"Traditionally, protected areas have been seen as the last line of defense against an expanding human footprint," Steiner told the gathering, which is organized by the International Union for Conservation of Nature. Instead, he said that such places should be seen as the "front line in defining a sustained relationship between humanity and nature."

Protecting nature has been seen as a tax on economic development, Steiner said, who argued that protected places offer a strong return on investment in terms of social and economic benefits. He cited the example of Australia's Great Barrier Reef Marine Park, which he said costs about $50 million (U.S.) to administer while generating more than $5.2 billion from tourism each year.

Yet very few countries include the economic contributions of protected areas in the decision-making frameworks that drive public and private investments.

The relevance of the economic, ecological, and social values of wild nature was articulated as part of the "Promise of Sydney," the congress's roadmap for the next ten years, meant to inform policy and economic decisions around protected areas.

Here are 5 more key themes and calls to action that emerged from the almost one thousand lectures, workshops, discussions, and dialogues held during a week of scorching spring weather in Australia's largest city.

View Images A jellyfish floats off the coast of Gabon, whose president announced at the World Parks Congress that a quarter of its waters are now off-limits to commercial fishing. Photograph by Enric Sala, National Geographic

1. Protect the oceans.

Oceans are the blue heart of the planet, but marine protection has lagged behind conservation on land. Oceans store a vast tonnage of carbon, buffer the climate, drive the weather, and provide food for billions. But only a third of the world's countries have protected more than one percent of the 200-mile (322-kilometer) exclusive economic zones around their shores, while the portion of ocean off-limits to exploitation remains paltry.

The congress called for a "fresh global understanding and respect for the ocean's role in sustaining human life" and committed to creating a global network of marine protected areas that will connect ecosystems from shorelines to high seas, allowing marine life to recover and thrive. New marine protections got off to a flying start at the congress when, at the opening ceremony, Gabon's president announced the closure of a quarter of his country's territorial sea to commercial fishing, which was followed by the signing of an agreement between the U.S. and the island nation of Kiribati to jointly support research and conservation in the vast Pacific Remote Islands Marine National Monument, an area of the Pacific Ocean covering 490,000 square miles (1,269,094 square kilometers).

2. Healthy parks make healthy people.

The link between ecological health and human health is not a hopeful guess but a proven reality.

"Studies have shown that when you have intact forests with multiple species, the incidence of Lyme disease is reduced," said Jonathan Patz, director of the Global Health Institute at the University of Wisconsin in Madison, who co-chaired a panel at the conference. "Biodiversity protects human health in that specific disease system. Other studies have shown direct evidence that deforestation increases the risk of malaria, which kills a million children every year and infects half a billion people a year."

Urban green spaces, protected watersheds, restored wetlands, and healthy oceans also lure people into the outdoors. Physical inactivity is a contributing factor in the alarming global increase in illnesses such as heart disease, cancer, chronic respiratory disease, and diabetes. Parks and protected areas, by virtue of the incentive they offer to experience nature, offer a path to human physical and mental well-being.

"As a medical doctor and a public health scientist," Patz said at the congress this week, "it is my professional opinion that conservation and park management can proactively save more lives, prevent more disease, and promote more public health than the public health sector can achieve."

3. Local communities matter.

Ten years ago, at the previous World Parks Congress in Durban, South Africa, Nelson Mandela laid down a challenge that still resonates today: "I see no future for parks unless they address the needs of communities as equal partners in their development."

Mandela condemned the unequal distribution of benefits and costs between developed and developing countries, between rich and poor, between the powerful and the marginalized, and set out a vision of conservation where the interests of indigenous people and local communities are respected and protected.

Sydney reasserted that message. The ability of local and indigenous communities to sustain livelihoods must be preserved, various speakers said, and their access to provisioning areas and sacred sites maintained.

At the same time, the congress admitted that indigenous peoples and local communities are often not recognized as equal partners in global conservation efforts and their traditional knowledge, cultural practices, and governance are not being fully harnessed in ecosystem management.

Yet with two-thirds of the world's land occupied, used, or owned by indigenous communities—and 80 percent of global biodiversity present in those lands—it makes sense for the conservation community to build partnerships with traditional communities to enhance and preserve natural areas.

4. Don't forget cities.

More than half of the world's population lives in cities. That number is forecast to rise to 70 percent by 2050, spurring the use of the term "Metro sapiens" at the congress. How are these people to connect with nature? Several delegates argued that protected areas and urban green spaces can address the nature deficit of the urban dweller, and also provide essential habitat and green corridors to support urban biodiversity.

If protected areas are to have a secure future, city populations must become their supporters, shareholders, and champions.

5. Harness technology to explore, manage, and protect.

Technology is transforming our ability to visualize, monitor, and understand the planet. Powerful remote-sensing tools reveal global data on everything from sea level to soil moisture, and representatives from Google circulated through the congress to explain how their mapping tools could visualize the new information.

The combination of satellite imaging and computer processing power makes it possible to see global deforestation in real time, at a resolution of 30-square-meter landscape pixels. Soon it will be possible to see where every industrial fishing vessel is working in any ocean in the world.