December marks the centennial of the death of conservationist John Muir, who founded the Sierra Club and helped create the Yosemite and Sequoia national parks, among others. SCIENTIFIC AMERICAN asked four speakers from November's World Parks Congress—a meeting held every 10 years by the International Union for Conservation of Nature to discuss issues concerning protected areas—what would be at the top of their to-do lists for the next decade.

“Muir saw the decline of the passenger pigeon. Now we are facing an extinction wave. To stabilize and reverse the loss of biodiversity, we have to reduce our ecological footprint; we have to produce more wisely and consume more wisely, using less energy and less land and less water.”

—MARCO LAMBERTINI, director general, World Wide Fund for Nature International

“We need to look at wetland restoration because we have lost so much: a 40 percent loss from 1970 to 2010. All of the water that is groundwater—the aquifers, the peat bogs, the salt marshes, the mangroves, coral reefs—all of these are classified as wetlands. That's why we have to tackle the issue from the global level.”

—CHRISTOPHER BRIGGS, secretary general, Convention on Wetlands of International Importance (Ramsar Convention)

“People don't realize the value in the illegal trade in wildlife is nearly as high as the trade in drugs. We need governments to take this seriously. We need legislation in countries that makes killing rhinos a serious, serious crime.”

—GREGORY CARR, president, Gorongosa Restoration Project (the nonprofit manages the one-million-acre Gorongosa National Park in Mozambique)

“Even where land is severely degraded, simple and cheap restoration methods can restore incredible biodiversity, replenish watersheds, attract migratory birds and shield the land from being ravaged by extreme weather. We may not recover everything, but the improvement is dramatic.”

—MONIQUE BARBUT, executive secretary, U.N. Convention to Combat Desertification