The UK is the first major economy to legislate to end its contribution to global heating. A target to cut greenhouse gas emissions to "net zero" by 2050 has become law after The Committee on Climate Change urged the government to take action as soon as possible to ramp up action to cut emissions urgently.
Lord Deben's relief on the day the target became law was evident at the BusinessGreen Awards last month. He explained how earlier that day, MPs had wondered why the UK should forge ahead when we are a small country. He explained that the UK had invented much of the technology that is causing the pollution we see today, and had become rich off the back of it, so we need to make it right.
What does it actually mean?
Hitting net zero - a 100% cut in emissions - will mean an end to the heating of homes with traditional gas boilers, more green electricity and a switch from petrol and diesel cars to electric vehicles, walking and cycling.
Emissions will have to be brought as near to zero as possible, and any remaining pollution in 2050 from areas including aviation will need to be "offset" through measures to cut carbon such as planting trees.
Manufacturers will find sustainable ways to produce so we don't just export our heavy industry and manufacturing abroad and increase global carbon emissions and pollution.
Lord Deben’s message to the room full of politicians, changemakers and business leaders was that the time has come to stop talking about - now do it.