An Auckland science lecturer says Sir Elton John paying for carbon-offsetting is not a 'get out of jail free card' on emissions.

There's been criticism of the music legend's environmental footprint after he took his private jet back to Los Angeles for an Oscars performance in between his New Zealand shows.

Sir Elton has said in the past he always pays to off-set his carbon use.

Professor Shaun Hendry told Simon and Phil many of these offsetting programmes rely on tree planting, which can take decades to actually offset the huge amount of greenhouse gases emitted each flight.

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