The flagship ABC radio current affairs programs PM and The World Today will be halved in length next year and Business PM will be axed, staff have been told.

PM and The World Today will both be reduced from hour-long programs to 30 minutes, radio current affairs employees were told at a meeting on Monday by Tanya Nolan, the managing editor of audio current affairs.

From 22 January The World Today, hosted by Eleanor Hall, will end at 12.30pm instead of 1pm to make way for a new “entertaining” national program on ABC Local Radio hosted by the former Triple J presenter Myf Warhurst.

Warhurst’s show, which is designed to attract 30- to 40-year-olds with a “lighter” offering, will run until 2pm.

Staff were told the rationale behind the changes was research showing there were significant increases in audiences consuming on-demand audio and digital content and a drop in the numbers listening to linear broadcasts on the ABC. The under-55 audience was not coming to the ABC as it once did, and something had to be done to reverse the trend.

Nolan, who also oversees RN Breakfast, AM, Background Briefing and RN Drive, told staff the shortened 30-minute PM and The World Today “would leave the audience wanting more”.

The head of spoken content, Judith Whelan, told staff the new local radio schedule would be unveiled on Wednesday and most of the time slots were changing.

From next year PM will air at 6.30pm on local radio so Drive can be extended from 6pm to 6.30pm in each state. Afternoons will run from 2pm to 4pm and Drive will run from 4pm to 6.30pm.

The changes mean the output of programmed radio current affairs will be reduced from two and a half hours a day to 90 minutes.

But reporters will be expected to do more live crosses into local radio programs because Nolan said there was “an over-reliance on packages” which can “kill the energy” of a program.

Nolan said she would prefer reporters in the field did more live crosses into Drive than longer reported stories for dedicated programs.

PM, hosted by Mark Colvin from 1997 until his death in 2017, is the sister program to AM, which turned 50 this year. First heard on 7 July 1969, PM is broadcast across the ABC’s local radio network after the 6pm news until 7pm. Business PM is a 10-minute dedicated business slot from 6.50pm to 7pm hosted by Elysse Morgan. A shorter version of PM is also broadcast on Radio National after the news at 5pm.

Journalists will also be encouraged to brush up on their conversational and informal talking skills so they can make podcasts and do more live chats.

The changes will fuel fears that Radio National – and linear radio in general – are increasingly under threat as resources are diverted to digital services.

The ABC’s managing director, Michelle Guthrie, has unveiled a restructure of content divisions that will see Radio National broken up and responsibility for its programs scattered around the corporation.

The major changes come just days after radio current affairs journalists shone at the Walkley awards for journalism. Jane Bardon’s coverage of Indigenous affairs for ABC Radio, Matt Brown’s international coverage of Islamic State for AM and ABC Radio’s senior business correspondent Peter Ryan’s coverage of the Commonwealth Bank scandal for ABC Radio were all honoured on Friday night.

Other ABC news programs to be decommissioned in 2017 include Lateline and Stan Grant’s The Link.