his year, World Habitat Day falls duringthe month when demographers predictour planet's seven billionth inhabitant willbe born. The future that this child and itsgeneration will inherit depends to a great degree on howwe handle the competing pressures of growingpopulation growth, urbanisation and climate change. Experts predict that by the year 2050, globalpopulation will have increased by 50 per cent fromwhat it was in 1999. Also by that time, scientists say,global greenhouse gas emissions must decrease by 50per cent compared to levels at the turn of themillennium. I call this the "50 - 50 - 50 challenge". Rising sea levels are a major impact of climate change- and an urgent concern. Sixty million people now livewithin one metre of sea level. By the end of thecentury, that number will jump to 130 million. Majorcoastal cities - such as Cairo, New York, Karachi,Calcutta, Belem, New Orleans, Shanghai, Tokyo,Lagos, Miami and Amsterdam - could face seriousthreats from storm surges. The nexus between urbanisation and climate changeis real and potentially deadly. Cities are centres ofindustrialisation and sources of emissions, but theyare also home to solutions. More and moremunicipalities are harnessing wind, solar andgeothermal energy, contributing to green growth andimproving environmental protection. Local efforts are critical to success, but they must besupported by international initiatives. We have alreadyseen progress, including the creation of the ClimateChange Adaptation Fund and adoption of the actionplan to Reduce Emissions from Deforestation and forestDegradation, known as "REDD plus". All countriesagree on the goal of limiting global temperature rise tobelow 2 degrees Celsius. Developed and developingcountries have committed to lower greenhouse gasses ina formal, accountable international agreement. Now we need to build on these advances. The UnitedNations Climate Change Conference in Durban thisDecember must achieve decisive progress.Urbanisation will be on the agenda at next year'sRio+20 UN Conference on Sustainable Development. On this observance of World Habitat Day, let usreaffirm our commitment to the important journey to amore sustainable future, and let us focus greaterattention on addressing climate change in the world'scities and beyond. nThis is an edited version of UN Secretary-General Ban Ki-moon's speech on World Habitat Day in New York, on3 October 2011. Above: Major coastalcities such as New York could face a seriousproblem from rising sea levelsRight: Ban Ki-moonTHE URBANISATION-CLIMATECHANGENEXUS144GLOBAL VOICESBAN KI-MOON, SECRETARY-GENERAL, THE UNITED NATIONSTPhoto: UN Photo/JC McIlwaine

Photo: UN Photo/Eskinder Debebe