The Senate has passed the government's revised climate bill by a single-vote margin after a late amendment carved out a larger transition fund for coal-region workers in regional Queensland and the Hunter.

What the amendment changes

The amendment lifts the transition envelope from $1.8 billion to $2.6 billion over four years, with the additional funds quarantined for retraining and small-business grants in postcodes within fifty kilometres of an existing thermal generator.

Independent senators who had withheld support until the final hour described the change as 'the minimum we could accept.' The minister responsible called it 'a serious answer to a serious request.'

What it does not change

The headline emissions target — a 48 per cent reduction on 2005 levels by 2030 — is unchanged. The bill's mechanism for compliance, a tradeable certificate scheme overseen by the Clean Energy Regulator, is also unchanged. Both were the contested elements in the original draft, and both survived.

"The amendment is small in dollar terms. It is large in political terms."

Whether the new fund actually reaches the workers it is intended to support will depend on the regulations attached to the bill, which are not yet drafted. The opposition has signalled it will scrutinise those regulations 'line by line.' Officials, in private, expect that scrutiny to be more procedural than substantive.