According to URBA 2000, a sustainable development organization, cities represent 2% of the planet's surface, but are responsible for 75% of the world's energy consumption.
These numbers are expected to grow in the years to come.
In China for example, demographics experts predict that by 2030, 75% of the country's population will live in cities, compared with 51% in 2011.
As people continue to move into increasingly smaller living spaces, city planners around the world are starting to think green.
It only makes sense: when space is limited, efficiency is a necessity.
Here at home, the City of Vancouver has pledged to become the 'greenest' city in the world by 2020 through various sustainable development initiatives.
Oakville, Ontario has received recognition for its eco-practices, which includes rolling out a city fleet comprised of hybrid and low emission vehicles.
China - which has a population close to 40 times greater than Canada - has been looking at sustainable projects as well.
One innovative proposal comes from Paris-based firm Vincent Callebaut Architectures.
The 'Asian Cairns' project, designed for the city of Shenzhen, consists of six massive 'farmscrapers' that aim to bring the countryside into the city.
The structure is comprised of 'living stones' -- pebble-like quarters that are fused to steel rings, linked to a central spinal column.
Powered by wind turbines on the roof, thermal solar cells and recycled water - among other things - each pebble consists of residential, leisure and office spaces, in addition to hanging gardens designed to improve Shenzhen's air quality.
"In this context of hyper growth and accelerated urbanism, the 'Asian Cairns' project fights for the construction of an urban multifunctional, multicultural and ecological pole," the firm said in a statement.
"It is an obvious project to build a prototype of [a] green, dense, smart city."
While the proposal is innovative in its approach and design, it will also be costly.
There's no word on when - or if - it will ever become a reality.