Boston Mayor Marty Walsh will address the Symposium on Modern Slavery and Climate Change at the Vatican on Wednesday, after his name was added to the agenda Tuesday.

The Mayor was added to the speakers roster after his omission was pointed out to organizers of the conference in Vatican City. One official said it was not a slight, but that cities facing the most severe crises of climate change and human trafficking were given priority at the podium.

Walsh, among nearly 60 mayors in attendance, will address the assembly Wednesday following a segment on economic development.

The Vatican conference objective is to do on a local level what many of their governments have failed to do on the national level: develop an integrated approach to reducing carbon emissions, wiping out human trafficking and effectively address income inequality "through a series of initiatives focused on the poor," in the words of Seattle Mayor Ed Murray.

Murray today spoke of building affordable housing along green mass transportation routes in his city, which echoes a program announced recently by Walsh. Walsh is expected to elaborate on this and the city’s efforts to address human trafficking by reducing prostitution.

Walsh is expected to meet today with Pope Francis.