Bin collection and street cleaners are holding out after a pay offer was made last week in a bid to stop planned strikes.
Union GMB was calling for a £2,000 pay rise and previously turned down an offer of an £850 a year increase for staff earning up to £25,000.
Now the union says it will be joined on Wednesday, the third day of the strike, by climate activists and international trade unionists in Glasgow.
GMB Scotland Organiser Sean Baillie said: “We are delighted COP26 climate campaigners and fellow trade unionists from across the world are standing with us to support our strike – the camaraderie and solidarity is growing by the day. But the council and the government need to realise that if we want cleaner communities and sustainable services, then we must invest in the green jobs we need and the workers who deliver them.”
Sara Shaw, Climate Justice & Energy Programme Co-coordinator for Friends of the Earth International, added: “We are proud to stand alongside workers fighting for fair pay and decent working conditions. Refuse workers in Glasgow are demonstrating the power we must build everywhere to tackle the climate crisis at its roots.”
TUC General Secretary Frances O’Grady said: “Climate justice and social justice go hand in hand. But while Glasgow hosts the climate summit, the key workers who keep Glasgow clean are not getting the fair pay and conditions they deserve.”
The message was reinforced by one of the world’s most senior trade unionists, Sharan Burrow, ITUC General Secretary added: “Council workers provide vital services for clean cities, and they deserve the respect of just wages.”
And Romain Descottes and Raphael Tillie from the CGT, France’s largest union, said: “The struggle workers are leading is similar as what our unions are doing in almost every sector of the working class, where bad work conditions and a lack of recognition are making their rules.
"Without workers’ voice, without workers’ decisions on how and what to produce, and without dignified working conditions, the fight against climate change won’t be able to succeed.”