At last it has come into force - the Kyoto Protocol to slow global warming by cutting greenhouse gases now binds the industrial world.
Can everyone live the Good Life by doing their bit?
But how much does it apply to ordinary people?
Away from the (energy-saving) lights of the global stage, the picture remains confused for those who want to do their bit to save the planet.
Even environmental groups like Friends of the Earth concede energy savings by individuals are hard to calculate.
Let the train take the strain, and the benefit depends on how many others do the same.
Boiling only the water needed for a cup of tea saves more or less energy depending on the type of kettle.
And change may start at home, but if industry still pollutes, is there any point?
But people persevere.
Floor to ceiling
With low-energy lightbulbs, household recycling, garden water butts and buying local produce, individuals try to make a difference on a small scale.
And sometimes on a more ambitious one.
Jacinta MacDermot, 38, strives to be environmentally-friendly right down to the organic paint on her walls and varnish on the floorboards.
FIVE TIPS TO TACKLE WARMING
Insulate your home
Recycle your waste
Flights pose a challenge - avoid domestic ones, take the train to Europe
Eat locally grown food in season
Tell your MP you care
Source: Friends of the Earth
With a colleague from their work at the Centre for Alternative Technology near Machynlleth, mid Wales, she renovated a run-down 200-year-old cottage using eco materials.
The pair took the knocked through cottage and returned it to its former state as two separate dwellings.
"We didn't want anywhere huge - it meant we could split this into two and end up with a house each that was the perfect size for one person.
"There aren't enough houses for everyone to have their palaces and it makes a lot of sense to live in small houses."
Each has their own kitchen, bathroom and stairs, but through an adjoining door, shared resources include "a vacuum cleaner, phone line, computer, garden, bread-machine" and sometimes the locally-produced milk in the fridge.
"I was in there only this morning rifling through her fridge," Jacinta admits.
An eco-friendly refit meant they could not find everything at the local DIY store.
Eat global, sleep global
Compostable organic paint and varnish came from a specialist supplier, a supporting post and beam from a local farmer.
Local building firms carried out any work that they could not. Loft insulation, sustainable wood sourced flooring and secondary glazing went in.
Heating and hot water are wood-fuelled using wood from sustainably-managed forests, lights are not the ever-popular halogen but low-energy bulbs, switched on and off individually.
Her neighbour's bed is a mattress of natural materials, made by a Welsh company whose factory runs on hydropower.
The car - not parked outside, but part of a 15-person-strong car share - runs on bio-diesel and is rescued if necessary by an eco-friendly local breakdown cover scheme.
Of the renovation, Jacinta says: "I had absolutely no idea when I started what it would involve - if I had I might not have done it.
"We were living there as well - for a time climbing in and out of the bathroom window because we didn't have any stairs."
"But I know every corner of it - what's under the plaster.
"It's nice to have somewhere that is as environmentally efficient as I could make it - the eco bit isn't just a surface thing, it goes deeper than that."
Life after the car
What relevance has it for the average urban dweller in a two-bedroom flat padding around on laminate floors?
There are four tips that translate to any household, she says - buy low-energy light bulbs, be aware turning on the TV is directly connected to a "coal-fired power station chucking out pollutants", buy energy from a renewable supplier and buy local produce.
AND FIVE MORE
Use environmentally sound building materials
Consider solar water heating to save money
Boycott goods with unnecessary packaging
Remember the three Rs - re-use, repair, recycle - anything is better than landfill
Make short journeys on foot or by bike
Source: Centre for Alternative Technology; Sustrans
For Nicky Parkinson, 39, a mother of two pre-school children from Bristol, it is all about the bike.
She job shares with her partner and they do the kindergarten run not in an MPV, but on a bike with a trailer. They both work for sustainable transport group Sustrans and only borrow a car for family camping holidays.
"People think I'm a bit of a martyr - but you make your choices about how you live and make it work.
"If the weather's really filthy then I don't cycle but I will in most weathers."
She has become increasingly aware of environmental issues and says she has seen the increase in the number of people cycling alongside her.
She also says cycling to work avoids Bristol's congestion, keeps her fit and be environmentally friendly is part of the family's eco efforts alongside doing up a house on a modest income and buying local food.
"I really want to be able to look my grandchildren in the eye and say I did my bit," she said.