The lord mayor of Belfast is to welcome to the city the mayors of Dublin, Manchester and Liverpool to discuss greater cooperation in tackling climate change.
Kate Nicholl will be joined on Wednesday by Dublin lord mayor Alison Gilliland, Greater Manchester mayor Andy Burnham and Liverpool city region mayor Steve Rotheram.
The four are to travel by hydrogen bus across the city for a day of engagements, including visits to a primary school and an environmental business.
