By NBF News

URBAN areas are set to become the battleground in the global effort to curb climate change, the UN has warned.

The assessment by UN-Habitat said that the world's cities were responsible for about 70 per cent of emissions, yet only occupied 2 per cent of the planet's land cover.

While cities were energy intensive, the study also said that effective urban planning could deliver huge savings.

The authors warned of a 'deadly collision between climate change and urbanisation' if no action was taken.

The Global Report on Human Settlements 2011, Cities and Climate Change: Policy Directions, said its goal was to improve knowledge of how cities contribute to climate change, and what adaptation measures are available.

Executive Director of UN-Habitat, Joan Clos, said the global urbanisation trend was worrying as far as looking to curb emissions were concerned.

'We are seeing how urbanisation is growing – we have passed the threshold of 50 per cent (of the world's population living in urban areas),' he told BBC News.

'There are no signs that we are going to diminish this path of growth, and we know that with urbanisation, energy consumption is higher.

According to UN data, an estimated 59per cent of the world's population will be living in urban areas by 2030.

Every year, the number of people who live in cities and town grows by 67 million each year - 91per cent of this figure is being added to urban populations in developing countries.

The main reasons why urban areas were energy intensive, the UN report observed, was a result of increased transport use, heating and cooling homes and offices, as well as economic activity to generate income.

The report added that as well as cities' contribution to climate change, towns and cities around the globe were also vulnerable to the potential consequences, such as:

•Increase in the frequency of warm spells/heat waves over most land areas

•Greater number of heavy downpours
•Growing number of areas affected by drought
•Increase in the incidence of extremely high sea levels in some parts of the world

Soweto, South Africa (Image: BBC) Southern Africa is considered to be one of the areas at most risk from the impacts of climate change

The authors also said that as well as the physical risks posed by future climate change, some urban areas would face difficulties providing basic services.

'These changes will affect water supply, physical infrastructure, transport, ecosystem goods and services, energy provision and industrial production,' they wrote.

'Local economies will be disrupted and populations will be stripped of their assets and livelihoods.'

A recent assessment highlighted a number of regions where urban areas were at risk from climate-related hazards, such as droughts, landslides, cyclones and flooding.

These included sub-Saharan Africa, South and South East Asia, southern Europe, the east coast of South America and the west coast of the US.

Clos told BBC News that while climate change was a problem that affected the entire world, individual towns and cities could play a vital role in the global effort to curb emissions.

'The atmosphere is a common good, which we all depend upon – every emission is an addition to the problem,' he explained.

But, he added: 'Consumption is carried out at an individual level; energy consumption is also an individual choice.

'This is why local governments and communities can a big role, even when their national governments do not accept or acknowledge the challenges.'

The report called on local urban planners to develop a vision for future development that considered climate change's impact on the local area.

It said that it was necessary to include mitigation measures (reducing energy demand and emissions) as well as adaptation plans, such as improving flood defences.

In order to achieve the most effective strategy, it was necessary for urban planners to seek the views of the local community, including businesses and residents.

However, the UN-Habitat authors said international and national policies also had a role to play in supporting urban areas.

These included financial support, reducing bureaucracy and improving awareness and knowledge of climate change and its possible impacts.

Clos was launching the report on Monday evening at an event in central London, hosted by the London School of Economics.

Meanwhile, the number of people living in African cities will triple over the next 40 years and by 2050 60per cent of Africans will be city dwellers, a UN report has said. In five years Lagos in Nigeria is set to overtake the Egyptian capital Cairo as Africa's biggest city.

UN-Habitat's boss said Africa needed to invest urgently in housing. He told the BBC that sub-Saharan Africa could learn from North Africa as Egypt, Libya, Morocco and Tunisia had almost halved slum areas in the past 20 years.

Some 199.5 million people in sub-Saharan Africa live in slums, the highest number in the world, the UN said earlier this year.

According to UN-Habitat's State of African Cities 2010 report, urbanisation is happening faster in Africa than anywhere else in the world. By 2030 the continent will no longer be predominately rural, it says.

Clos, UN-Habitat's executive director, said that cities were attractive places for those wanting to relocate. 'People are looking for a better future and they think the city can offer that,' he told the BBC's Focus on Africa programme.

Agricultural reform and poverty in rural areas were another reason for the trend, he said. Many African cities already face major problems of overcrowding, irregular supplies of water and power and poor transport infrastructure.

But urbanisation often led to improved living standards, if action was taken to provide adequate housing, infrastructure and services, Mr Clos said.

In 2015 it is estimated Lagos will have 12.4 million inhabitants. The UN also forecasts that the population of Kinshasa, the capital of the Democratic Republic of Congo, will increase by 46per cent over the next 10 years to become the fast-growing city.

By 2050, Africa's urban population is expected to reach 1.23 billion. The report warns that climate change is causing a serious problem for some cities. With many of Africa's cities built by the sea, millions of people risk losing their homes in the coming decades because of coastal flooding. It says the West African coastline is retreating by between 20m and 30m every year.