He said the authority had to cut £600m in total over the six years of cuts up to March 2017, which was £200m more than originally thought. He blamed successive cuts in government grants for the "horrendous" financial situation.
Some of council services would have to be completely "decommissioned – we will simply have to stop doing things" to meet targets because the problem was of "such a magnitude and we can’t salami slice – we have reached the end of that game".
A spokeswoman for the local authority said it was too early to say how heavily parks and open spaces, or any other services, would be hit. The consultation will start next month and is due to end at the turn of the year.
At its height, the council employed 19,000 full-time members of staff but that figure would fall to less than 15,000 over the next few years. It would be mid- to late-November before the authority had more details on how many and what sort of jobs would be affected.
Birmingham Open Spaces Forum vice-chair Emma Woolf said: "In some ways this is more of the same: people talk of a golden age of parks but there hasn’t been spending for 20 years. It’s awful to say but parks are used to this.
"I’m positive Birmingham will look at ways of being innovative and recognise the value of what it’s got, and get other people like health and sports services to pay. It is already working with volunteers and academics on reviewing ecosystems services."