The concept of environmental thresholds could weaken progress on sustainability at Rio+20, says global change scientist Simon L. Lewis.

Rio+20 must launch SDGs to guide countries through complex development challenges, argues Colombian ministry official Paula Caballero Gómez.

Conflicts over shared water resources could be mitigated through science-based environmental cooperation, argue Saleem Ali and Pamela Griffin.

Plastic bags are too practical to be banned, but policies to manage their use are necessary to protect the environment, says Lilia Casanova.

Poverty, governance and population growth — not physical availability of water — are the real challenges for the continent, says Roger Calow.

World leaders must promote effective land use methods to mitigate drought, says Luc Gnacadja of the UN Convention to Combat Desertification.

Biopesticides are better and safer than chemical pesticides — policymakers must do more to promote them, says insect ecologist Manuele Tamò.

Reforms in the Arab region should focus on transitioning to a green economy, argues award-winning environmental advocate Najib Saab.

Feeding South-East Asia's rapidly growing population requires a second Green Revolution, says Crispin Maslog.

Peter Messerli and colleagues argue that reforms in agricultural policy will be needed to build green economies in the developing world.

The proposed Sustainable Development Goals need more focus on health to continue the progress achieved with MDGs, argues Priya Shetty.

Pacific islands must build capacity for their own environmental monitoring to tackle both local and global problems, says Ben Ponia.

Improving access to information technology can help communities assess their own vulnerability and boost local planning, says John Waugh.

South-East Asia has suffered from neglecting planning for disasters. Governments must heed the warnings and act now, argues Crispin Maslog.

The proposed UN World Environment Organisation is badly needed to give poor countries a strong voice in green policy, says Zakri Abdul Hamid.

Cities face many social, economic and environmental challenges, and must facilitate innovation to cope with them, says an editorial in Nature Geoscience.

Population forecasts may be based on unrealistic assumptions of demographic change in the developing world, warns Carl Haub.

The current drought in northern Kenya has deep roots in the current practices of pastoralists that need to be addressed, says conservationist David Western.

Combined strategies are needed to meet the world's rising demands for food without further damage to biodiversity, says Jason Clay.

Assessments of bioenergy must consider the potential benefits for rural development and food security, say Lee R. Lynd and Jeremy Woods.