James D Wolfensohn: To save the world from itself, we must act now

Last spring, the UN summit in Monterrey, Mexico, spurred poor countries to commit to improve policies and governance in exchange for promises by rich countries to deliver more aid and open their markets. The World Summit on Sustainable Development in Johannesburg next week gives us the chance to put those words into action.

What should the world expect from Johannesburg? Perhaps the best way to answer that is to imagine what kind of world we want. Are we going to leave as our legacy a poorer globe that has more hungry people, an erratic climate, fewer forests, less biodiversity, and is more socially volatile than today?

According to the World Bank's World Development Report 2003, the next 50 years could see the global population swell by 50 per cent to 9 billion people, and the world's gross domestic product increase fourfold to $140trn (£92trn). Social and environmental strains threaten to derail development efforts and erode living standards unless we design better policies and institutions.

Development policies will need to be even more closely focused on protecting our forests, fisheries and farms – and making them more productive – if the poor are to narrow the equality gap that has emerged in the past 50 years.

If we stay on the road we are on, the signs do not appear encouraging. By 2050, the world's annual output of carbon dioxide will have more than tripled while 9 billion people – 3 billion more than we have today and mostly living in developing countries – will be tapping into the earth's water.

Food needs will more than double. All this in a world where extinction already threatens 12 per cent of all bird species, and 25 per cent of its species of mammals. By 2050, for the first time in history, more people will be living in cities than in rural areas. Without better planning, the stresses from immigration and population shifts could create new social upheaval and desperate competition for scarce resources.

Yet these trends also offer windows of opportunity if world leaders and policy makers muster the courage to pledge – and follow through – bold actions over the next 10 to 15 years.

Most of the capital stock and infrastructure that will be needed in coming decades does not exist. Better standards, increased efficiency, and more inclusive means of decision-making could mean these assets are built in ways that put fewer strains on society and the environment.

Similarly, as population growth slows, economic growth will translate more readily into lower poverty and higher incomes, provided that development over the next few decades has been handled in a way that does not destroy natural resources. We must strive for the Millennium Development Goals, which map out a world where poverty is cut in half by 2015.

If individual incomes in the developing world grow by an average of 3.3 per cent annually, they would reach $6,300 a year by 2050, nearly one-third more than that in current upper/middle income countries. What would this mean for ordinary people? Their basic need for shelter, food and clothing could be affordably met. Life expectancy would rise to 72 years in poor countries, compared with 58 today in those nations with the lowest incomes.

Of course, dramatic economic growth would pose potentially enormous environ- mental risks. We must protect our forests and fisheries from over-exploitation, halt soil degradation, ensure our water supplies are used efficiently, protect ecosystems and limit emissions from factories, cars and households.

Developing countries need to promote democracy and transparency. Rich countries should increase aid, support debt reduction, open their markets, help transfer technologies needed to prevent diseases, and increase energy efficiency and agricultural productivity.

Civil society can act as a voice for dispersed interests, and oversee public, private and non-governmental performances. A socially responsible private sector should create incentives for companies to pursue their interests and environmental and social objectives. And the global community must work on issues such as climate change and biodiversity.

If we safeguard our vital resources and social stability, we will attain the growth rates essential to cut poverty. It would be reckless of us to reach the Millennium Development Goals in 2015 only to be confronted by chaotic cities, dwindling water supplies, increased emissions and less cropland than we have now.

The author is president of the World Bank