New targets to eliminate the gases driving climate change from Wales' economy and way of life are to become law.
The Welsh Government said "business as usual" was no longer an option.
Changing weather patterns are already "wreaking havoc" and acting now is "the right thing to do for our children and grandchildren", it says.
The move brings Wales into line with the UK push for "net zero emissions" by 2050.
However, environment minister Lesley Griffiths said she wanted to "get there sooner".
It will mean huge upheaval - from replacing hundreds of thousands of gas boilers in people's homes, to potentially finding new ways of making steel at Port Talbot without burning coal.
But the process will lead to new green jobs, and improvements to people's health while meeting international obligations to try and avoid a dangerous rise in global temperatures, the government said.
It will publish a revised action plan ahead of the major UN climate change conference - COP26 - in Glasgow later this year.
Advisers at the independent Climate Change Committee (CCC) have already warned Wales is not on track to meet existing, less stringent goals to slash emissions.
By 2018 - the latest year for which data is available - Wales had seen a 31% fall in greenhouse gas emissions compared with 1990 levels.
New legal targets will force a 63% reduction by 2030 and 89% by 2040, with Wales reaching 'net zero' - effectively a 100% cut - by 2050.
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