The Climate Change Minister believes slashing 24 million carbon credits will fix the struggling Emissions Trading Scheme.

Companies buy the credits in quarterly auctions - to offset their pollution output.

Repeated failures to sell credits triggered the Climate Change Commission to advise there are too many cheap units available, in order to drive down emissions.

Minister Simon Watts says it's a simple supply and demand fix, but he can't speculate on the price implications.

"What we've done here today is make sure we've put some credibility back into this market - which hasn't been the case in the past."

Changes to unit numbers kick in from 2025.

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