Middle-class consumers will increase to 4.8 billion by 2030 and 95 per cent of them will be from developing countries, said United Kingdom Foreign Secretary's special representative on climate change, Prof Sir David King.

He said, currently the world has 1.8 billion middle-class consumers and that three billion more were expected by 2030.

"Ninety per cent of that growth will be from the Asia-Pacific region as cities in the developing world face the steepest challenge," King said at the Low Carbon Cities (Opportunities and Challenges) forum held at British High Commissioner Simon Featherstone's residence in the capital, Monday.

He said there would be an estimated 3.3 billion urban population in Asia and 1.3 billion urban population in Africa by 2050.

"All countries must work to address the current consumption rate of the world's resources..proper urban development is key to managing the growing global population," he said.

King said due to the increasing middle class consumers, several challenges included the fact that 95 per cent of food production was highly dependent on oil, 80 per cent of the world's population live in areas with high threat to water security.

He said 60 per cent of the world's ecosystem was already either degraded or unsustainably used and 11 per cent of remaining natural areas could be lost by 2050.

"Based on climate change such as rising sea levels and temperatures, it is clear we must radically change our behaviour soon," he said.

Green Tech Malaysia chief executive officer, Ahmad Hadri Haris, who served as the moderator, said it was time for all parties to work together to address climate change before it was too late.

Ahmad Hadri said there was no better model of good urban development than Iskandar Malaysia, which has a comprehensive green development plan from 2006 to 2025.

"I think there is a lot of strong will to get things done. We should look at the whole perspective for cities in Malaysia and how we can progress in a sustainable way," he said.

Meanwhile, Head of Iskandar Malaysia Planning and Compliance, Maimunah Jaffar said it had a Low Carbon Society blueprint with a 12-point action plan to help it reduce carbon emission.

She said the points include integrated green transportation, green industry, low carbon urban governance, low carbon lifestyle, community engagement, green buildings and construction.

"Malaysia is already at the forefront when talking about carbon reduction, with policies and incentives in place. But it is also currently still on a voluntary and not regulatory basis, so it is up to the local authorities or government agencies whether they want to take steps to reduce their carbon emission," she said.

About 100 local and international participants from government and private sector attended the fruitful three-hour forum.