Scotrail have published new proposals for timetable changes, with some services returning to their more frequent pre-pandemic levels.
However, Mr Greer, who lives in East Dunbartonshire, said this is not the case for local lines, including Lenzie and Milngavie, where the current reduced timetable is to operate until May 2023 when a further review will take place.
He hit out at the service from Lenzie rail station.
Mr Greer said: “From around 6.20am to 7.50am it appears that the service through Lenzie will only stop every half an hour. That’s worse than the current timetable and clearly isn’t good enough for early morning commuters.
"The default for suburban stations on the routes into Glasgow should be a service every fifteen minutes throughout the day. At peak times though, that level of frequency should be the absolute minimum.”
Services to Milngavie previously operated every 15 minutes until late into the evening but in recent months they have been reduced to half-hourly outwith peak times.
The Scottish Green MSP has long campaigned for improvements to the Milngavie line, including the relaying of the second track to boost performance and for construction of the long-proposed Allander station.
He recently secured a £5 million fund which was used to extend the platform at Milngavie station, reducing the number of delays due to resting trains blocking those due to depart.
Mr Greer urged local residents to respond to Scotrail’s passenger consultation before it closes on Friday, October 1.
He said: “This is a self-fulfilling prophecy from Scotrail.
"If your justification for reduced services is that fewer passengers are returning to the railways, you are simply guaranteeing that outcome by providing them fewer services to return to.
"With Scotland’s transport emissions still rising and air pollution returning as a public health issue at Bearsden Cross post-lockdown, we should be making it easier rather than harder to use public transport.”
“Timetable reductions on other routes are scheduled to last only until May of next year.
"I have written to Scotrail to ask why they believe extending reduction on the Milngavie line until the following year is necessary.”
For more information on train times in the local area, visit www.scotrail.co.uk/west-scotland.
Greer added: “Given that Scotrail will be transferred into public ownership during this period, I have also written to the Scottish Government’s Transport Minister, asking that he intervene as soon as possible to ensure rail services in Bearsden and Milngavie return to a greater frequency.
"I would urge local commuters to make their views known to Scotrail before their consultation closes. You can do so at www.scotrail.co.uk/west-scotland.”