The Staggers 21 July 2015 Has Boris Johnson snubbed the Pope? The Mayor of London is missing a meeting of the world's mayors at the Vatican to discuss climate change with the Pope. Why? Boris Johnson's MP duties seem to have stopped him attending Pope Francis's climate change summit. Photos: Getty Sign UpGet the New Statesman\'s Morning Call email. Sign-up The Pope has invited the world's mayors to a two-day meeting, beginning Tuesday this week, to discuss his new favourite subject: climate change. Following his landmark encyclical on the environment last month, in which he warned us of “serious consequences for all” if humanity fails to act on climate change, Pope Francis has invited mayors of cities around the world to meet at the Vatican to discuss the fight against global warming. There are over 60 attendees, including such high-profile figures as the mayor of New York City Bill de Blasio, and the mayor of Paris Anne Hidalgo. The full list of attendees and programme is available here. The mayor of London Boris Johnson was invited to attend, specifically to participate in a workshop on modern slavery and climate change, and a Symposium on Cities and Sustainable Development, at the Pontifical Academies of Science and Social Sciences on 21 and 22 July. But he isn't there, and nor has his office sent a GLA representative in his place. A City Hall spokesperson explains his absence: The Mayor was unable to attend the Vatican’s events this week due to diary constraints. He is however delighted that the Vatican is highlighting the issues of climate change and modern slavery, and congratulates Pope Francis on his initiatives in this area. Addressing the challenge of climate change is one of the Mayor’s key priorities and he has led the world in city-based efforts to reduce emissions, including his announcement of an Ultra-Low Emissions Zone in central London to be introduced in 2020. Although it is unclear what Johnson's diary constraints were specifically, he was present at the late Welfare Bill vote in parliament the night before the conference, in his capacity as Tory MP for Uxbridge. And an insider tells me he also has Commons commitments on Tuesday, the first day of the conference. His non-attendance at the Vatican, depriving London of a representative at a global mayoral meeting about tackling climate change, suggests two things. The first is that climate change is not a priority (as the comment from his spokesperson denies). And the second is that his duties as an MP are clashing with his mayoral commitments, and he has been compelled to pursue the former over the latter, which will only add to the characterisation of Johnson by his detractors as a "part-time mayor". The only UK delegates at the conference are the Bristol mayor George Ferguson, and the Manchester mayor Tony Lloyd. Ferguson, known for his green credentials, spoke at the conference this afternoon about what Bristol is doing to reduce carbon emissions. He wouldn't comment on Johnson's absence, but is clearly aware of how useful an event like this can be, and urges all city mayors to join the conversation: I regard it as a great honour for Bristol to have been invited to address this vitally important conference, hosted by the Pope at the Vatican. Cities are at the frontline of climate change in terms of both problems and solutions, and I implored all city leaders to unite on the related issues of poverty, modern slavery and climate change. De Blasio has used the Vatican summit to make a pledge to cut New York carbon emissions by 40 per cent by 2030. › State-sanctioned prejudice is at the heart of David Cameron's approach to countering extremism Anoosh Chakelian is the New Statesman’s Britain editor. She co-hosts the New Statesman podcast, discussing the latest in UK politics. Subscribe For daily analysis & more political coverage from Westminster and beyond subscribe for just £1 per month!