Union leaders are planning to fight proposed changes to public sector pensions introduced by the Alberta government on Wednesday.

The Public Sector Pension Plans Act would raise the age for people to qualify for a full pension and lower inflation-proofing measures.

The government says the changes are necessary because the plan has an unfunded liability of more than $7 billion.

Alberta Federation of Labour president Gil McGowan says the liability is coming down and the plans are financially sound.

He and other union leaders plan to make those points in a letter to all MLAs.

“We want them to defeat this bill but if they don't, we are basically making the promise that we will be reminding our tens of thousands of members about which MLAs voted to undermine the retirement security of tens of thousands of Albertans,” he said.

McGowan says the Tories are trying to impose pension changes through legislation rather than negotiating with the unions.

If the bill passes, the changes will come into effect in 2016.

Current rules allow workers aged 55 with 30 years service to retire with a full pension. The changes raise the age to 60 with 30 years service. 

Anyone who retires earlier than that will face a five per cent reduction in their pension for each year.

The legislation also changes cost-of-living adjustments for pension benefits earned after 2015. The adjustment will stay at 60 per cent of the rate of inflation. However, instead of being a guarantee, the rate will be a target. 

With files from the Canadian Press