Fighting climate change means different things in different cities, as this snapshot illustrates:

- Vancouver, Canada -

Environmentalism and tourism are intertwined in Vancouver, a city of 600,000 nestling between beautiful mountain peaks and the Pacific Ocean.

Since 2007, a swathe of green measures has cut CO2 emissions from buildings by 20 percent, landfill by 23 percent and road trips by 27 percent. The city has a vastly-expanded network of bike paths and two new rail transit lines.

In 2015, Vancouver set a target of 100 percent renewable energy by 2050. The province's electricity supply is already 93 percent renewable, mostly hydro.

Like other port cities around the world, Vancouver is faced with rising seas and more destructive storms as a result of climate change, for which it intends to revamp storm-water systems and management.

Forestry and mining remain the province's major industries, but the city has made a big push to attract investment in less polluting sectors such as high-tech and film production.

- Chongqing, China -

A megapolis of 18 million people, Chongqing is a manufacturing hub for cars, motorcycles, steel, aluminium and many other heavy-industry goods.

Its citizens have gagged for decades on some of the foulest air in the world, made worse by a landscape of hill-lined basins that trap pollution.

Zhou Jie, a 28-year-old advertising industry worker, said she worries constantly about pollution and global warming.

"I would be very willing to switch to a low-emission and low-polluting lifestyle if the government asks us and is willing to subsidise it," she said.

The giant municipality -- whose administrative area covers 30 million people -- has an ambitious programme to encourage lower-carbon practices.

A buy-back programme launched in 2013 has taken tens of thousands of high-polluting vehicles off the road. High-sulphur coal and diesel are banned within city limits.

Chongqing wants non-fossil fuels to be 15 percent of its energy mix by 2020.

Beijing has promised China's world-leading carbon emissions will peak by "around 2030."

- Los Angeles, California -

Despite improvements, spawling Los Angeles still has some of the most polluted air in the United States.

But that status may change as California ramps up to enact among the most ambitious environmental policies in the world.

Last September, Governor Jerry Brown -- who calls climate change "the existential threat of our time" -- approved legislation requiring the state to cut greenhouse gas emissions 40 percent below 1990 levels by 2030.

The state also aims to generate 50 percent of its electricity from renewable resources -- notably wind and solar energy -- by 2030. Buildings are to become twice as energy efficient by the same date.

Three-quarters of all waste must be recycled by 2020.

As for Los Angeles, stricter fuel emissions standards for vehicles are bound to help.

But there will be new challenges: temperatures in the sun-soaked city are expected to rise by 2.8 degrees Celsius (5.0 degrees Fahrenheit) by mid-century.

- Lagos, Nigeria -

Battered trucks and cars on the highways of Nigeria's main commercial city spew black clouds of exhaust, while chronic electricity outages mean that most businesses and homes rely on gas-guzzling generators for power.

The air often tastes of petrol.

Despite its exploding population of 20 million in a low-lying coastal area, Lagos has done little to adapt to future climate change.

"There is often a big gap between plan and implementation," explained Ademola Omojola, an associate professor of geography at the University of Lagos.

"The capacity to manage it at the local level isn't there."

With limited green energy options, people are forced to rely on fossil fuels.

With government corruption endemic, the private sector may be better placed to adapt to climate change.

A privately managed city for half a million people, for example, is under development on 10 square kilometres (4 square miles) of reclaimed jutting out into the Atlantic.

Dubbed the "Dubai of Africa", Eko Atlantic boasts an eight-kilometre (five-mile) -long wall designed to prevent the ocean from eating away the Lagos coastline, and thousands of homes with it.

But the project -- far too expensive for most of Lagos' inhabitants -- has been tarred as a "climate apartheid".

SOURCE: AFP bureaux